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Post by henri on Jan 25, 2015 17:08:11 GMT
wow , thats sum fancy software your runnin there sime , this has gone a bit high tech for me ,makes me nervous ,bit of a puter phobe , am still reading through earlier stuff ,page 3 ,fnar , at this rate i might never catch up, will have to wait til mornings coffee kicks in , H
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Post by vespasco on Jan 25, 2015 19:15:49 GMT
I think maybe you are over complicating this a little but at least it irons out all the wrinkles Yeh i agree its a bit ott for this particular subject. I dont think put the question quite right....see below for a simpler version of the hypothetical question... The area of the narrowest part of the inlet hole just needs to be bigger in area than the carb. * PxGuRu Ji Bang!!! One answer and the doubt is gone! Hi! Im Barry Scott and I ....... The timing of the rotary inlet is related to the porting of the barrel being used and the purpose it is being used for. Standard inlet timing doesn't suit anything else but a standard barrel being used for driving around an Italian city, with a girl riding side saddle on the pillion If shes italian, im going back to stock! ;P Heres the (hypothetical) question i was trying to ask..... No numbers involved. I hope the answer is C ! Come on H. Your input is welcome and valuable Have you thought about making a living doing CAD type stuff?! Hahahaha!! Apart from me i bet there's a few (handful of)? people out there that would pay some beer tokens for some of that info/design potential!?!?!? Are you planning on a CNC machined 500cc monster?! Come up...fess up.
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Post by vespasco on Jan 25, 2015 20:03:33 GMT
Without trying to go off track, heres a quicky that i thought was, barely interesting, to some! Ahaha! but hopefully it should help clarify another technical query that crops up (once in a blue moon)! I kinda came across it while the verniers were out. How much tolerance is there between the sealing pad and the crank? This example is of a 1974 Rally 200 with the same size 98mm diameter crank typically found on the PX125/150/200. In this example above, its 0.175mm. Using 98mm crank (not measured)! (Unavailable)! Basically, the sealing pad in this example, 'relatively un-worn' cases, is exactly 0.50mm thick. How much tolerance is there for wear? I really dont know at this stage. Maybe well find out one day!
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Post by sime66 on Jan 26, 2015 6:21:36 GMT
Re: your 1st sketch and question above; you’ve only got the one option, haven’t you? Because of the width of the sealing pad/crank web; it has to be long and thin at crank, AND now we know to make it at least as big as the carb, which in your case it already is, which I think is why I found it easier to swallow, you can make the length suit your timing, or I can anyway - looks like your up the creek Barry! I think you might have asked before in the thread how much bigger area than the carb area is OK for the inlet; and now that might be something you need to know. Here’s your numbers, just as accurate as I can get from your rubbings, are: Crank Inlet – Top of Casing – 589.7 mm² Crank Inlet – Inside of Casing – 485.7 mm² Here’s your drawings I’ve emailed to you as .jpgs too: I think mines going to be easier to work out ‘cos your inlet timings already a bit wonky, and your inlet at the crank is already bigger than your carb, so for you the question above………….? What I’m going to do now is see what timing and area I can get by using the available area on my sealing pad, then look at what I need on the crank to get ideal timing. The transition there is dictated by the width of the sealing pad; the others I’ll just tidy up the edges and corners and keep an eye on the areas, but on mine there’s room to play about. I noticed that the back carb stud is an area where cutting is restricted, and care needs to be taken; don’t know how deep they go, but going into the rear part of the pad looks like going close to that stud. Re: your 2nd sketch and question (not quite as far above as the above one, above the one above), I’ll have a measure of mine later. I have an old crank and an old set of cases, so I’ll see what I’ve got. 0.175 sounds a lot though; there’s plenty of talk about it on ModernVespa etc., but I couldn’t quickly find actual numbers from anywhere reliable. enough for now; Monday morning, stuff to do...........
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Post by henri on Jan 26, 2015 10:08:28 GMT
right ,a sick kid n morning off work an i'm jus about caught up ,will need to go back n re-read but couple of things ,sorry if this is backtracking but , on page 3 sime mentions bells figures for rotary valve timings , there rotary disc figures ,not perfect for are crank timed inlets but a lot closer than piston ported figures , will have to check but for a tourer a inlet open duration of around 150deg is best ,a racer more like 170,an a inlet opening upto 10deg before transfers close is best .the fresh charge is encouraged to flow by the low-pressure of previous load leaving , inlet tract shape is basically never smaller than carb opening an gradually increasing without steps/jumps to its largest orifice in the cases against the sealing web of crank , a inverted cone thats slightly squashed/ovalled on its lower edge is the best description my over caffienated noggins got ,the wider cross section causes a drop of pressure which helps prevent the fuel condensing an dropping onto cases so much , most recently in other types of engines the inlet tract length has been researched n developed ,with only polini to my knowledge making venturi/velocity stacks for spaco's ,which so far ive heard good reports on , an i'm tempted by a 30mm okw n inlet manifold for 60 euros on kraut evil-bay , undecided coz of difficulty to jet exactly , but theres a app/website reccomended by sir stick in this months scootering which seems to make it a doddle , 30mm is to big for a 150cc but just manageble for a tuned 180, mines for a 200 ,maybe , then tuning ya inlet length is just slackening 2 clips n moving carb back n forth hunting the sweet spot , very tempting , H
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Post by sime66 on Jan 26, 2015 12:42:20 GMT
I'd value opinions on this please chaps; just received - 9 out of 35 teeth are like this - I think someone's taking the p*sh:
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Post by henri on Jan 26, 2015 15:46:49 GMT
sorry cant remember wheres it from , if e bay i'd contact n send photo's askin for a refund ,partial atleast as that 4th gear is crackered , i think there 30 quidish new from beedys ,so mention thats what ya want back , is it all on the fourth gear , whats the rest like an shaft an all, if you dont get a satisfactory answer describe it as mislisted/damaged an e bay return it , you wont have to pay postage that way an will be refunded original cost an postage ,even if seller trys to dodge it, e bay guarantees it, but it takes a while , at least you planned on using your own primary as the 1 from that box was probably totally trashed , looks like somebody spat a tooth n it got graunched , now we know why this chancer was just sellin a shaft n loose gears ,the rest was even beyond his low morals to sell. bit of a let down for ya sime ,know what that feels like , bloody chancers n wide-boys , H
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Post by vespasco on Jan 26, 2015 16:53:24 GMT
That sucks!! Remember you have the option to fit a 125 4th gear, if it meets your requirements. Dont solve that issue tho'. Bingo!!! Henri!! Thats exactly the answer i was hoping to hear!! (inverted cone description - spot on). Treat yourself to some more cough syrup of your choice Remember my question was more hypothetical than anything. Not strictly vespa only stuff! But that answered it superbly. And to top it off i just happened to have read that in my guide too!! Spot on. Now im 100% , well ok, 99% confident that i fully uderstand what is ideal! Tfft!! Hahaha! Falling short of more inlet duration figures for our vespa rotary valve inlet. Race/tour/stock. Some figures i have for the differences between rotary disc and our rotary valve, for what seems quite a small engine: labelled as a "normal"(stock/untuned) engine: Both have : Exhaust port duration @ 140° Transfer @ 110° Inlet duration for (vespa type) rotary valve inlet = 120° (60/60) And for rotary disc valve = 190° (140/50) So are we also agreeing that, for our vespas, its still ok to have that overlap, so long as the porting in the cylinder is suited. (Which would be determined by what youd use it for etc etc) Ive been really tempted by the vortex carb top. If theres one cheap enough i just will try one! But am reluctant due to silly things like; noise difference and warmer air going into carb and it will no longer look stock. But the positives are looking more and more attractive. Ill try a larger air corrector first. I know that really improves acceleration and smooths out any 4 stroking at low revs. Ill swap a polini exaust for one thats for sure Inlet pipe length was again sorted by Mr. Magoo. See simes link ^^^^^ its in there. A 30mm carb on a vespa 200? (Your cosa)? Is that tuned? What exhaust would /have you got to match that up with? Again. Hats off sime. Nice work!! So my carb inlet @ 589.7mm^2 would be equivalent to a 27.4mm diameter carb! Interesting!! And the orifice on the pad is pretty much the same as a 24mm carb! Which makes that inlet a 'cone' - big top, small bottom!! The carb studs are 36mm long. The one (above pad) on my Rally 200 sticks out 23mm, so 13mm depth minimum. I dont know if the 0.175mm tolerance on pad/crank is a lot or not!!?? Take into account crank play and bearing play. It also shouldnt touch/be too close as this will create heat from friction - loss of performance. Im sure its out there already. I think i got my sums right!? Im happy with the measurements i made. Maybe the crank is just that little bit bigger than 98mm ?
*Edit
Whats the name of that app??
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Post by sime66 on Jan 26, 2015 17:07:50 GMT
Cheers, H; I’m on with sorting that out. I suppose I’ll have to decide whether to sling it back at him, or see what of it I can use; I sent an email earlier, but haven’t had a reply yet, so haven’t taken it apart to look at it closely. I had asked him to check and confirm the condition of the teeth before the sale, but its the cheek to send it after that, and the wasted time and effort, and I do not want to change single cogs either . 125 EFLs are easy enough to get; it was the 35T that i particularly wanted. That’s detail though; the real thing that gets me about that is people thinking they can knock out crap; if it’s only good for the bin then chuck it away, don’t dump it on another scooterist! It just isn’t done. A risk you take with 2nd hand, but not from another scooterist.
Anyway, back to the plot; your summary, after catching up this morning was great to read, and we’re all now looking at the same job with the same aim again. On that subject too, I had an excellent, detailed response from Scootercentre (Ger) within a few hours of asking them a tech query on the Mazzucchelli Race crank this morning, which I think, when I sit down and look at the numbers, will give me the info I need to decide about my Inlet size/cutting and my crank choice/cutting. I’ll be back with that info as soon as I’ve digested and processed it to see what it means. I think there’s about 17° more, but I also think a lot (half) of it is ATDC, so got to see what it means on paper. I’m leaning towards buying a crank, rather than cutting it, but ain’t ready to get the Dremel or the Wallet out yet.
I’m right off buying 2nd hand from just photos though; fingers burnt, not everyone has the same standard of parts or practice.
Vespasco; we keep doing this – yours has appeared while I’m replying to Henri; I’ll take yours away now and digest that lot, and do me sums on the crank, but I’ll Be Back!....................
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Post by vespasco on Jan 26, 2015 23:01:37 GMT
I may repeat a few things thats been mentioned already but wanted to get it out there, to be sure in my mind and tie up any loose ends in my mind..... So from pencil rubbings of my rally 200...and with the help of sime and his 'SuperComputer'... Pad orifice = open duration @ 37.8° (using 98.35mm as diameter of pad). Area - same size (v close) to 24mm carb = 485.7mm^2 Si24/24e = 475.8mm^2 Top of case inlet/gasket face orifice = 589.7mm^2 = 27.4mm diameter equivalent. My Mec Eur 60mm crank must therefore have: With 181° total inlet (107°/74° duration) - 37.8° = 143.2° of inlet on the crank web. Seems a lot?! *edit: yes it is a lot! And wrong! = 128° But so long as its not more than 180° on the crank! So one thing ive learnt is: We can now work out if its best to open the sealing pad orifice, or the crank, or both Very likely its going to mean, at least, opening the pad, for the reason its smaller than the carb inlet orifice on a stock vespa. At least, from our findings here, on a stock px150. Although, thinking about again, it may be the same size as the 20mm carb!! I need to check that! *Edit - Checked.. by my calcs (using the given mm^2), your px150 pad orifice is equivalent to a 21.8mm carb. Also by my calcs the 24mm carb is actually 24.6mm!! And the 20mm carb is actually 22.8mm!! Ive often heard the si26/26 is more like 25.5mm !!?? Although for Rally 200, the pad orifice is about the same/ equivalent as the common stock 24/24 carb. So its not necessarily true for all vespas!!! In that instance, it would advantages to cut the crank, not the pad, to achieve desired inlet timings, if using the stock 24mm carb! So all those instructions about cutting cranks to suit the timing on all those kits out there is maybe not as necessary as first seems!!?!! The area to concentrate on is the the opening time of the inlet, when compared to the transfers closing. Minimum, it should be equal timing - transfers closing at the same time as the inlet opens. This will give a broad range of power. For more top end revs, at the expense of a little less 'user friendly' low to mid range power, the opening time can overlap, by as much as 25 - 30° + on top end race motorbikes but more like 10° max on your average/well tuned vespa! This is all very closely related to the conditions in which scavenging and transfer takes place. The moment at which the transfer port closes is the point at which the deperssion in the crankcase begins to appear. Having the inlet open while the transfers are still open would create a bigger depression in the crankcase and as such draw even more fuel to the fire! Longer overlaps can be made when the exhaust is such that it creates a bigger depression in the crankcase. The effect of closing the inlet too late: If there is more pressure in the crankcase than the cylinder at the time of inlet closing you will likely suffer blowback through the carb. Closing too late is nowhere near as important as opening at the correct time. Could always go reed valve!! Haha!!! Im going to go and punch some figures into that spreadsheet thingy now!!
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Post by sime66 on Jan 27, 2015 8:53:47 GMT
Yours still looks very ‘numbery’ to me vespasco, so going on what was previously advised, I’m going to continue on my tack to continue what I was working on before checking through your stuff. I’m comparing the options of cutting my crank against buying another race/touring crank; the best info I’ve found is from Scootercentre, which combined with a bit of deduction has given me the following: This is what Alex at Scootercentre said: all the crank shafts that are signed with the term „racing“, have a longer intake duration.F.e. an original Piaggio crank shaft of the P200 will close the intake 52-55° (depends on the engine casing) ATDC. The Mazzucchelli crank shaft will close the intake 70°-75° ATDC. So the intake duration becomes longer. This will increase power and torque from mid range rpm until peak rpm and will push the peak rpm a few revs higher. It is not recommended to open the intake at the engine case in direction ATDC together with a Racing crank shaft. It is always a good idea to open the intake, to have more degree BTDC. The maximum should be 120° BTDC. – A good and fast road engine likes an intake duration from 120° BTDC to 65° ATDC – that should be very easy to realise at a P125 engine. I’d like to recommend you to make serious measuring of the inlet timing at your engine. For the P125 it is sometimes not possible to come to the recommended intake duration, because of the very short rotary valve surface of the casing. In that case you can open the intake at the engine but only that far, that you will have a minimum of 1,5mm around the intake left to seal the rotary valve.I get from this the following; the implications and disagreements are evident: 1. The Mazzucchelli Race crank gives 18-20° more, but it is ATDC. 2. Do not open the inlet more on the ATDC side of the inlet if using this crank. 3. The maximum before BTDC is 120° 4. The limiting factor on 125/150 is the pad, leave enough to seal (1.5mm) The conclusion is that the Mazz Race Crank doesn’t solve the BTDC deficiency, and increases the ATDC more than is my target :- I went on to see how much chopping of my standard crank would be needed to achieve the 125/55 previously given as my target:- If I open up my inlet, I have plenty of area (enough to be a bit more precise than cutting it to the max available). Unfortunately, on the crank itself and on the inlet, the areas that affect the inlet opening, BTDC, are the trickiest areas to cut. (around the big-end, and around the stud) – I note that Henri and Alex both reckon on 120°, whereas I’ve been aiming for 125°, so I would like to know how critical that figure is, especially as there isn’t an agreement. I would also like a better understanding of the effect of the ATDC timing, and why, for example, the Mazz Race crank adds it there; is it because an increase is good, and it’s easier to do it there? My conclusion, for my engine, is that I don’t want to pin it down precisely until I have the barrel to measure, and can come up with all figures together, taken as a whole cycle for all ports, but I need a better knowledge of how important 125 BTDC is, and what the limit on ATDC is; I know Henri and vespasco have touched on the matter; filtering the pertinent information from the last few posts is my next job. Unfortunately the only time I can give the numbers my full attention is first thing, and I’ve run out of time again this morning without getting that far. · The Mazz Race crank gives me somewhere between roughly (from photo and imprecise email only) 107/62 & 116/72 – no good. · Cutting my inlet and crank leaves the timing flexible (see drg) ; there’s room to tweak and target is achievable, but cutting has its own concerns and complications, and can’t be finalized yet anyway. · Cutting my inlet is also desirable to achieve the increased area, certainly for the 24 carb. 22nd Jan, Pxguru said: “to get a reasonable inlet time, the maximum inlet hole size and a little ground off both ends of the crank should do it”And after going round the houses and plenty of head scratching and discussion, I see no reason to disagree. That doesn’t mean I won’t play with the numbers nearer the time, but at the moment, for me deciding what I’m doing for my build, going too ‘numbery’ seems to be clouding the issue; my sketches show me more clearly what I need to do. It may be that some of the stuff written recently above has answered some of my unknowns, with the agro and distraction over the sh*te gearbox yesterday, and time running out this morning, I find myself falling behind, and not wanting to get dragged into to much tech stuff just at the moment; I hope you don’t charge too far ahead before I’ve caught up! Incidentally vespasco, if you still have that gearbox lying around, and now that you’re mobility is improving, which is good to hear; I would be interested to see what you have – I am still in the market for an EFL 150/200 shaft and loose gears (or maybe a 35T 4th, but to be honest I really don’t want to use any part of that gearbox inside my new build, however useable the rest of it may be; I’d rather buy Indian than cobble something out of that sh*te). As a final note on that subject I will add that the bloke who sold me that sh*te either has an extremely low engineering standard for his own superficially shiny scooter builds, or he has a habit of knowingly selling on knackered stuff that he wouldn’t use himself; it’s either shoddy standards or despicable ethics, I don’t know or care which, I will not trade with him again. I won’t name him, but he will probably read this. That’s the end of that subject; I’ve got it off my chest and time to move on – I’ll start with reading back over yesterday, and hope my stuff isn’t out of date, and your stuff fits in with my progress…………..
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Post by henri on Jan 27, 2015 9:18:38 GMT
sorry vespaco, bit too much caffiene , a inverted truncated cone is what weve got as stock really ,not really cone but 4 sided pyramid with rounded corners if ya see what i mean , work on opening the inlet is to turn this upside down n get a truncated cone ,small at top ,big bottom , on simes px cases an my cosa's thats the effect of the drilling ,more on cosa as the drilling is angled giving a bigger "footprint"/opening . an for interest most rotary valve stuff is kart based nowadays ,where the extra width of a carb on end of crank dont matter ,its a lovely system to play with ,with practice ya can swap a disc in 20mins =new inlet timings , an for the polini vortex/stack ,i'd like to see what results you'd get keeping airbox n rubber an moving filter inside frame ,similar to what i did on missus cosa ,tho used a k&n type n kept carb top filter ,as i also have concerns of where the foam filter draws air from , an my cosa 200 isnt tuned yet , still thinking on it , it came with spanky new barrel/piston/pin/ n head ,so would be a shame not to use em, an a new crank unfortunately or i'd def stroke it (not in that way,fnar),considering a bit of porting/raising n such like . sime ,ive been caught by crappy sellers aswell an it does put you off ,but on the whole ive mostly good deals an have met/messaged some really ace scoot-bods ,an others too, theres always a small % of total rip-off merchants ,an your guy saying he'd checked em first is a crock, is what you gave worth it for a shaft n 3 gears ,if so i'd be tempted just to name n shame an keep em n get another 4th ,i might have a non-piaggio 35th in shed ,yours for postage,tho prob not efl box . thats good info n replys from scoot cent ,ive found if ya go on "google translate" n message krauts in german ya get a better response ,tho its invariably in better english than my german,they really respond to the politeness . vespaco , the keihin n copys jetting website is www.kyajet.com ,had a noodle on there last night an it seems to make it a doddle ,as doing it by code book is a mare ,ive only done it once an run a mile anytime since anybody asked , an soz got to ask ,your exhaust swap thingy , check ya selling/wanted ad n maybe message rab ,as what exhaust i can get is nxt step in what tune i aim for on my lump,i'm sort of letting fate decide as i cant.had sort of decided sip road2 ,but for style a in-ya-face expansion chamber is more in keeping with the projected scoot,my street racer vbb/smallie/cosa frankenscoot , an theres a sip3 now , 240 quid for a sito-plus thats been hacked apart n looks like it was welded up by a blind monkee , from piccys ive seen anyway . an ya comment on reed valve at end , ive seen a slimmed down lml reed used below a spaco to cure sealing pad damage ,but it looked restrictive ,tho the reed manifold are expensive .ive a lml reed n thick ali plate in shed an have been meaning to experiment/torture on my px150,if i get too it i'll post any results to ya .H
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Post by sime66 on Jan 27, 2015 9:57:06 GMT
sime ,ive been caught by crappy sellers aswell an it does put you off ,but on the whole ive mostly good deals an have met/messaged some really ace scoot-bods ,an others too, theres always a small % of total rip-off merchants ,an your guy saying he'd checked em first is a crock, *1) is what you gave worth it for a shaft n 3 gears ,if so i'd be tempted just to name n shame an keep em n get another 4th ,i might have a non-piaggio 35th in shed ,yours for postage,tho prob not efl box . thats good info n replys from scoot cent ,ive found if ya go *2) on "google translate" n message krauts in german ya get a better response ,tho its invariably in better english than my german,they really respond to the politeness . *1) It's hard to say whether what's left is worth it. - Until I know what option to put it right I end up taking. for the money, I prefer to express my utter disgust and not waste more time on him, or with sending it back, and seeing what use I can make of what's left. But now that I own it, I have taken it apart and the shaft looks pretty abused too, which is why I say I don't really want any part of it in my new engine build - I cannot envisage being happy closing the cases on my new engine with that sh*te inside. I'll take opinions on the shaft later, but not as part of this agro, which I'm sick of right now. I am seriously open to all offers and options to put it right, and I'll continue looking for the right parts too; I know I'll encounter worse problems on the build, but I find myself at a low at the moment - the a**e on ebay with the carb has just said he won't send it, or refund until the Ebay enquiry/dispute I raised for non-delivery expires next week (he hasn't even sent it, won't send, and won't refund), so I've gone from engine parts sorted to loads of bits missing again - browned off. Naming Him? No, I'm better than that; I will say he sold me some other sh*te last year, and this was part of making amends for that, so you could probably work it out. But the matter is done as far as I'm concerned - I will not return; the offence caused by passing of trash as good second hand - twice! and the agro of returning and trusting him to refund is greater than the money; he will not offer any part-refund without complete return - so, impasse. I have the moral high ground, and the money isn't that important to me; it's people thinking it's an OK way to behave that saddens me. I've said enough on the subject; don't want to make more of it here than I already have. I got your opinions yesterday, and I've let it be known now that I'm still looking for the parts, so that's more than enough on the subject. I have a 35T non-EFL off the other gearbox; that's non-switchable isn't it? I only ask because you mention a non-EFL one you may have - I was going to compare them sometime actually, but don't believe it's an option. *2) I always do that out of courtesy with the translator when talking to overseas suppliers; I agree, I'm sure it gets good results, and we shouldn't expect everyone to speak English in my opinion. I will definitely give Scootercentre a go with a decent purchase; their site is excellent for tech info, and my first experience of Customer Service is excellent too. Their prices are the same as SIP, as is their freight - Є5. In this case, though, I don't think the Mazzucchelli Race crank is what I want. (subject to checking myself, which I must confess I'm not confident about - I've been distracted by rows, and too p*shed off to concentrate - might take a short break from it actually - clear my head........)
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Post by henri on Jan 27, 2015 11:07:23 GMT
yep def agree it might be time to walk away for a bit ,let ya head clear n not let the idiots derail ya plans , dont agree with not naming n shaming ,but then i'm a guy who picked a fight with the guy in mirror when shaving once ,an lost it , 1 broke mirror 1 gnarley scar on nuckle , an i'm slowly switching to scooter centre as sips service has deteriated recently ,reckon theve got too big n succsesful, only bugbear is constantly havin to translate every page unlike sip that whole site goes english ,but that might be me missing a "translate whole" button/option . an thinking coz of diff in cruccy ya right cant mix efl n e gears , was offerin mostly to try n cheer ya a bit ,but if theres any doubt on shaft n other gears for piece of mind alone send back , its a delay mate not a death-knell, ive never had a plan A thats come off , ive always had to switch to plan B,C,D etc ,its only dead wen ya get to Z , H
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Post by vespasco on Jan 27, 2015 16:55:13 GMT
1) the mazzy crank gives extra 18-20° atdc - not much you can do about that without a lot of work 2) don't open inlet any further atdc . makes sense with those figures 3) ideally, on any tuned 2 stroke, weve learnt that the max inlet opening BTDC is equal to the closing of the transfers (and upto around 10° overlap on tuned vespas. Much more on modern race bikes). Maybe the max 120° btdd SC suggests is aimed at that particular crank. (As otherwise it would give a total duration of more than 185°) 4) good to know! Although personally, id probably stick to same minimum piaggio have made, which on my particular sealing pad is 3mm...although id probably risk 2mm if needed and on SC recommdation. Opening inlet up to max would be (just to make it easier to picture in the mind) equivalent to a 28.2mm venturi on the carb. Weve been told this is ok with a 24mm carb. I guess ideally youre looking for the crank that gives you the correct timings out of the box (after you open your pad orifice to match the carb)!! The only number you really need for this is the transfers closing angle. If thats 120° btdc, then your inlet needs to open there too (or upto 10° more) Cutting 10mm (8.5°) off a crank wont affect the balance of an already unbalanced crank.... Not too much!?!?! Just an educated guess really. Lots of people do it without problems. I think/hope we all agree that opening inlet btdc will give, in your particular situation sime, more benefit than closing later, as it improves the low to mid range, which is what youd prefer i believe. It seems that basically, (on a well set up motor) whatever you gain at high revs by alterating the inlet timing, you will loose at low revs...and vice versa. When the inlet opens and closes determines where you can gain most power. Comparing a total duration of 180° as an example: Open early (and therefore close earlier) - power low down Open late (and close later)- power higher up Both stages are related to the porting of the cylinder and exhaust system etc. The critical thing, with rgard to inlet timing opening/closing, is when the trans close and the inlet opens. Ill have a look for that gearbox.. And if theres a spare 4th gear its yours! And if youre still pi***d off ask Gaz for one of his 'induction cones'. Youll feel better!! No worries H, you answered my question the first time. And perfectly. I wasnt necessarily intersted in the actual shape of orifices of the 'cone', just the physics behind it!! Out of interest only, do you know the inlet timing of the cosa? Tunutitus is contagious!! Beware!! My symptoms are getting worse too! Im not sure the kyajet can be used for a si carb tho Unless you use the same air corrector size on both jets??? Ive ordered a couple of bits from SC (on sunday eve) and their delivery date is Wednesday, tomorrow!! Sip normally arrives on a friday with a weekend order. Sip - out of stock on some parts i wanted which were also more expensive!! I know we all refer to SIP loads, mainly due to their specials, good website and vast catalogue with lots of pictures and fairly well detailed decriptions but they are certainly not the only shop out there! H, look out for and click on the little british flag on the right hand side. Of the SC website. It will convert to english. Pm sent to gaz ref polini pipe
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Post by vespasco on Jan 27, 2015 17:39:19 GMT
Heres whats lurking in my shed..... Am Any use to anyone?? 2 x 200 driveshaft efl Set 200/150 gears to suit Selector rod Px indicator switch new The 2 x loose gears are unfortunately... A 125 4th 36 teeth, with worn inner face!!!! Not really usable 3rd gear. Looks ok I need to check these over properly but theyre looking for a new home.... If you get stuck sime, you can have the complete drive but its been ear marked for possibke future project..tunititus is spreading rapidly!!.. But if that dont take off youve got first dibs. Plus i need to look closer as to whats what exactly!!
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Post by sime66 on Jan 27, 2015 18:25:39 GMT
Mate! You know it makes much more sense to resist the tunitis, and send that driveshaft and gears to a good home where it will have a lovely second life in the countryside, with lots of fresh clean oil and not too much thrashing. Seriously though; absolutely, first dibs yes please – it’s exactly what I’m after (PX150/200EFL), if it passes your inspection, and if you decide you’re not using it. I know you probably need it, but if ever you do decide to part with it………. I’ll catch up on today’s posts first thing in the morning, chaps – I think we’re pretty sorted now though. One thing I picked up quickly scanning through, but not going into it too much today, is the approx 180 – leaning towards the BTDC for low-end power and towards the ATDC for high revs power, which is a nice simple way to picture it, and why the ‘Race Crank’ ain’t what I’m after. Anyway, more attention to it all in the morning. Also vespasco, I had a look at your port maps at lunchtime; I’ve done one (the one marked-up 'Pinasco for 200 - 5SB'), which I’ll send soon with a couple of questions so I can finish it, but you said you’d sent two to draw-up – I’ve only got one, so I think you need to send the other; maybe check what you think you sent to me. Also (the last also) - I whacked a big lump of Euros over to Italy earlier today, so hopefully getting my barrel to play with soon, and pin some numbers down in a week or so. Wounds licked; moving on.......................
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Post by pxguru on Jan 27, 2015 18:51:41 GMT
Sime, Sounds like the right conclusion to me; you don't want a race crank if it has too much ATDC. 125/55 or there abouts will suit your needs
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Post by sime66 on Jan 28, 2015 7:03:59 GMT
Pxguru; I went all round the houses and reached the same conclusion as you had said about a week before, but the investigation of the subject made it worthwhile. Vespasco; thanks for email yesterday, and kind offers. I said I’d post some photos for opinions, but even I know that this lot is beyond worthless, and only fit for the bin. I’m after a complete new 150/200EFL driveshaft/gears again. No worries, I’m happier not to be trying to cobble something together from this crap; it can all go back, there’s nothing of it I want, and I need to buy again, so I’ll have my money back, which wasn't my intention, but I'm given no option: I won’t bother with getting opinion of the shaft, the damage is difficult to photo, so I’m just lumping it as one transaction – full return – full refund; I don’t have to be quality control to sort out the good stuff to send back for someone who couldn’t be bothered or lied before. End of subject; just to tidy it up and now move on.
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Post by henri on Jan 28, 2015 8:42:33 GMT
somebody reckons there a dragster n doesnt use a clutch much , typical damage for a high bhp lump thats been "crashed" thru the box sprinting/dragging from lights , ugh, bin it n sweet talk vespaco. vespaco, havent noted cosa timings yet , have my eye on a cheap mazzy 60mm crank with my interest heightened by guru's post in the stroking a P2 thread bout good results with stock barrel, the lump came cheap with broke fly cases an seized (rust)crank ,but with new stock crank/barrel/head .ive only stripped it so far except for clutch n crank coz i'd forgot my clutch nut tool ,hopefully will get it done an can measure up this sat morn before stevie vespa turns up for a rear shock job.that n pulling the front mount is as far as i'll get on it for a week or 2 ,need my cash to mot n tax my V100 ,the 1 i was supposed to be curing my "tuneittis" with. the kyajet link wasnt meant for spaco's ,just a idea that other carbs are now more available/jettable now the info's there to take the scary bit away , an thanks for the flag tip ,its been driving me potty tryin to decipher there german .an the polini pipe PM shud of gone to rab not gaz , i might withdraw my fat goldfish from the offer as it will have a better memory than you an you'd prob forget to feed it .a carved carrot looks just as gud an never needs feeding . H
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Post by vespasco on Jan 28, 2015 12:53:58 GMT
I like carrots aswell as goldfish, so no worries there I did actually pm Rab, not Gaz... For some reason i always get you 2 guys mixed up!! No offenc meant!! As for a 60mm crank....i remember seeing a link to a frnch/belgium website with MecEur stroker for about £80 i think.. Well cheap for one of those. I can recommend them anyway, i have one.. I paid a little more than that tho'! And holy crap sime... All those gears are absolutely worthless!!! Youve been stitched up im afraid to say. Name n shame the toe rag. Instant karma will get him!!!
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Post by sime66 on Jan 28, 2015 13:00:05 GMT
He's refusing to pay return postage; it's legal now; I'll consider name & shame, but it's awkward, and not my style - I absolutely wish him bad Karma, but I must tread carefully now. At the moment I am too angry to make decisions - been arguing it this morning - won't make decisions when I'm angry. Don't really want to dissect it here; I have your opinions and advice, which I appreciate, but I'd still like to deal with it myself - I don't need it on here too.
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Post by sime66 on Feb 5, 2015 10:09:32 GMT
Moving on from the sh*te gearbox, I’ve had a week measuring and drawing my engine, and I’ll quickly show some of that before moving on to more technical stuff concerning my new barrel, which arrived a couple of days ago. First the 3D drawings and animations, which took quite a lot of time and effort, isn’t of much technical value really, but was a challenge I set myself as a break from the agro with buying parts off thieving w*nkers. Everything is measured and drawn accurately, and I’ve added as much detail as the software and my computer can cope with, so this is about as complex as I can draw at home with the equipment I have: Then a couple of animations: Now to the more technical bit; the port timing, which has got me scratching my head about how best to go about it, or the best sequence of jobs to measure and then decide the dimensions I need; some I have from measuring the new DR177 barrel: Transfer Heaght: 47.6mm Exhaust Height: 37.7mm Some I need to know, but can’t get until I build (or do a dry build? With old bearings in? assembling crank/piston/barrel/head?) These are the ones I’m not sure how to get at this stage: Static Deck Height: Squish: Inputting the measured barrel dimensions, and leaving the Static deck height and squish as zero for now, it is clear from what was said before, that I will need quite a bit of jiggling (2.5mmish in total?) – Important note here; this jiggling is only adjusting the barrel height, not cutting the barrel – I’m finding it difficult enough to measure accurately; I have no faith in cutting the barrel myself – my skills and eyesight make it unwise in my opinion. Here’s the table from the data I have at present: Quickly, also, with the online calculator, but limited to the bits I have so far – just as a check against my own: So that’s where I’m at with it. I’m trying to decide: a) How much of a ‘dry’ build I should do to get the static deck height and squish now, or whether this information from just the barrel is enough for now. b) Whether the information from the barrel dimensions is enough to tweak my port timing diagram to give me some target port timings, relative to each other, or whether it’s too early to do that, or whether I need to do some ‘dry’ building now to check it before going ahead. I’m a bit out of my depth at this stage of it, but there’s plenty of time to understand what I’m trying to do and decide how best to go about it. If any of you clever chaps can give me any pointers at this stage, about how my numbers seem to be stacking up, or how best to go about tweaking them or finding out the missing ones, I’d be grateful. Hopefully recording it at every step and this early in the process will help others too when and if they come to tackling it. Before we proceed, I must admit that the port timing stuff we did last year is still only very tentatively lodged in my brain, and I need to progress slowly to understand it again, so I hope you don’t throw a load of numbers at me, or I’ll have to struggle to keep up again! I will just add that I am still looking for a PX150/200EFL driveshaft and gears, and I’d also like to decide whether myold Dellorto 20 off my scooter is definitely going to be good on this engine, or just an adequate compromise; in both cases I’m torn between taking a chance on waiting for and buying good old stuff, or settling on new non-Piaggio (Indian) stuff of uncertain quality. Buying stuff isn’t urgent, but I’ll be happier when I have all the big bits sorted. Just thought, another question; I was surprised how roughly cast the head was – I’ve never seen a brand new one before, so maybe it’s normal. Do I want to Dremel these rough bits off and then smooth it over, or are they OK? Didn’t expect to see it so rough: QUITE A LOT OF STUFF TO CHEW OVER THERE, CHAPS!!
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Post by henri on Feb 5, 2015 10:40:16 GMT
yep the dr's are a bit rough castings ,no polishing= cheaper than others , i just take of any big bobbles as they can "carbon up" an become a hot-spot/glow plug , use to polish my chambers but stopped when i noticed it didnt really decrease any coking or improve gas flows to a measurable extent . an a "dry build" an measuring actual timings/deck/squish is the best way to go , its the only way to get actual "true" figures to play with , will go back over your "estimations" above an see if anythings popping out . that is when the "thing" that just popped up below the desk starts to behave again,real sexy animations an graphics sime , maybe you should put a "parental guidance" rating in front of it .nearly choked on my coffee an my blood pressures popping off the scale ,but noodling round with them as you go will def help you visualise the steps you want to take ,an more important the 1's ya dont ,H
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Post by vespasco on Feb 5, 2015 19:19:39 GMT
I've been watching that animation since 12pm....Up and down and round and round and open, closed and up and down..... SoupHerb Imagine being able to use that with variables in timing, angles, base packers, heads, pipes, gears...all with a tuning guide similar to the spreadsheet one mentioned previously, giving results to aim for and to expect. Punch in the numbers, voilà! Easy!! Hahaha! Once you've matched your cases to the barrel, if youre going/need to do that, and once youve altered your inlet, fitted beatings and seals etc and once youre happy with your gearbox internals working smoothly, then theres no reason why you shouldn't be able to put the cases together permanently. This will leave just the top end to play with. As for the crank, without a good tool, its more never racking pulling in and taking out the crank without a hammer/whatever! At that stage you will get your proper squish measurements. Its the only true way. Unless youre happy to install, then pull your crank, with no damage. The top end should be dry build with gaskets, torqued head. As you'll be taking the cylinder off and on a few times, you wouldn't necessarily need the piston rings fitted when measuring your squish etc. Makes it a bit less nerve racking. I wouldnt rely on those figures without knowing your proper deck height. Squish can come later. The head will probably be the last thing you work out. You probably have the theoretical deck height within your drawings/calculations. For curiousity, that would give you more to aim for than using 0mm (unless of course thats what it already theoretically is)! Remember how much, even just 0.2mm, makes a difference on the port timings! Im going to have a sort out, the driveshaft n gears have your name on them sime. I would certainly smooth out that head, potential hot spots. And whats a hot spot not!? You could polish it if you wanted. No harm will be done. But before you go to work on it, work out your deck/squish/volume, just in case you end up getting it machined to suit your needs better. Again, as a more usable guide, in your notes/drawings that you have are hidden your 'theoretical' volume/squish (if you can measure the volume of the combustion chamber @ TDC that is)! Once you have deck height, all will fall into place.
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Post by pxguru on Feb 5, 2015 20:29:12 GMT
Impressive graphics. To put some meat in the sandwich if you are not doing anything with the barrel then you are going to need a 1mm packer and not much more or the blowdown will be far too short. This will leave it a bit compromised but will be ok. With the 1mm packer and that new head the squish will be about 2.5mm, which is a bit c**p. In my ideal world; 2.5mm packer, raise the exhaust port 1mm and skim 3mm off the top of the barrel
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Post by sime66 on Feb 5, 2015 20:45:39 GMT
Cheers chaps, I’m going to sleep on it before I reply properly, but I think I need to decide what I can do now/next and what has to wait. Off the top of my head, jobs I can usefully do next: · Check matching cases with barrel – it was on my mind that, although I’ve drawn both accurately, I haven’t actually put them together and looked at them yet. They are very similar, but I’ll have a better look, get my Sharpies out and do some photos – next job. · Cut crank inlet and crank – to the 125/55 anyway, without other timings sorted? · Tidy the head. · Dry Build for deck height/squish?* · Thinking about how to pin down some more measurements/volumes, and if I can use any ‘theoretical’ values – those transfer and exhaust measurements are as precise as I can off the barrel; what I don’t know is where the barrel is relative to crank and piston. I can do some work on the head. Then there’s things that might have to wait: · Dry build for deck height/squish?* · Final target port timings and gear ratios I’ll add to that overnight. ^*The reason I’m unsure about the dry build is that I can see the sense in leaving it until the engine is one piece and then just concentrating on the top-end, but I can’t do that until I’ve cut the cases and found the gearbox, so if I wait till then I’m held up now. But in no real hurry; maybe I should wait and get my plan of action better thought out, and do some hands-on dirty jobs. I’ll sleep on that thought. I know about the crank tool. I also remember being advised against it before (on last year’s build) I used a wood wedge between the flanges before, which I think I recall being told was best – if that opens a can of worms I’ll go back and find it (it’ll be in 'preparation for rebuild' thread somewhere). The business between dry build with old bearings or waiting for proper build is something to think about. I didn’t have any value for deck height at all, so I just put my measurements in to see what timings they would give me at zero (which was T109.27 – E158.15) and I just looked at what mm adjustment would get me nearer the T124 I have in mind – I put in 2.5mm and got +13.89 on the transfer timing, which gives me T123.16; just an idea of whether my barrel measurements were roughly as expected, and how far out they might be to get near to target – nothing precise or technical at this stage. When I have my deck height and squish, my 2.5mm will come down accordingly. I did realise that my above table prints too small on the forum, so I’ll blow it up and do it again here, to see if I can show it better (it is just a start point – lots of stuff missing/incomplete): Later, I can slow the animation down, or pause it at crucial port timing points to show what’s going on better. What I haven’t worked out how to do is show it any bigger on the forum – it’s full size on my 21” widescreen LED here, and there’s much more detail that doesn’t really show up on an animated GIF. Anyway, I’m bored with that for now, and as I explained before, the greater precision (which is necessary for the drawings to be a useful tool) the slower the processing and the harder my old computer is working to get anything done. It is exactly my cases, crank, and top-end, and I can re-do it later to be precise for the ports when I have them fixed in place relative to cases, but it’s after the event really, rather than helping to decide – just for fun and to get a picture of it, and time consuming. I’m gonna get me calculator and tools out now instead…………. I keep thinking about how to torque the barrel down without the head to check the deck height; I’m thinking something like plastic washers to protect the face – what do you chaps do? Here’s another one for you old-hands on a different subject; I’m told that a Corteco Viton metal seal doesn’t fit in old-PX casings. I had intended to get the best for my engine, and thought that was what I wanted, but I’m advised (By Wasp – very helpful chap, Dave) that “Early cases have a groove machined in to the casing where the oil seal is held. This is for the rubber on a normal oil seal edge to sit in to, to help hold the seal in place. The later metal type seals, seal using an interference fit however there is not enough surface area to keep the seal in place on earlier type cases because of the groove.” Does that ring any bells with you lot? That I need to use a rubber one for these cases? The seals are just another thing that I’m investigating in the background, and that one surprised me, but makes sense, so I wondered if it is correct. Anyway, a quick reply is turning into a full-blown essay, so I’ll leave it there, have an overnight ponder, and see if I have any inspiration to share in the morning. Pxguru, your’s popped up whilst I was doing my ‘quick’ reply, so I’ll go away and ponder it. I understand what you’re saying, I’d need to better understand how much of a compromise on the OK-versus-crap scale it is to make a final decision, but I am very concerned about cutting my barrel myself, and it defeats the object getting someone else to do it, even if i could find anyone – the exhaust port and skimming the barrel, so I’m just going to acknowledge what you say and let it lie for now until I’ve got real numbers. (I don't even think there is 3mm to take off the top of the barrel). I noticed the drop in blowdown you mention though. Lots to think about.
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Post by vespasco on Feb 5, 2015 21:13:02 GMT
So im guessing from above ^^^ , (and looking at the head) it actually is ऊँ deck height. Sorry, i mean 0mm
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Post by vespasco on Feb 5, 2015 22:52:00 GMT
i missed your post earlier sime, i was actually referring to guru ji s post. if youre going for the 123° transfer then the 125/55 inlet would be fine You can pin down some measurements by meadring your head.. A large syringe (25 - 35ml is ideal) use oil, 2 stroke or even water (add a little fairy luquid). You can also measure the piston displacement. Your software will probably be best for that?! Theres also free cylinder head developement software...i think its on Toms Tuning Tools Also, as a starter, you can measure to the bottom of the exhaust port, minus 57mm (stroke) = deck height Slowing dwn the animation would help to visualize everything clearly Plastic washers are fine, anything softer than the casr iron barrel will be fine The brown metal viton will fit but are extremely tight in the old style cases. My view of that is, if its always had plastic seal, carry on using plastic. Once you put a metal seal in there, keep using metal seals. The metal ones seem to be that little bigger. Although having said, to against the grain and to try something new, i ended up, for some strange reason fitting these..... Im led to believe these fit both old and new regardless. Ive only managed a few hundred miles with this seal fitted so its far too early to say if they are any good. have a look in here for the different clutch seals vespa.proboards.com/thread/4507/installing-new-bearingsAnd always use loctite on your final build! Id be looking at getting the timing where you want it (for touring the hills) with the least amount of work....which looks to me something like: 1mm base packer - giving 1mm deck height - which also allows tolerance for skimming your head for good squish and compression. Raise exhaust 2mm Raise transfers 1.5mm. All of these things you can do yourself, if you are up for the challenge Have a practice dremelling on something of similar material , to find out how accurate you can be
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Post by sime66 on Feb 6, 2015 8:43:21 GMT
Righto, it’s good to have lots of bits to think about and learn; here’s what I think is the best way forward: · Leave decision about barrel mods ‘til later, when ‘ good<->ok<->a bit crap’ scale-o-meter can be judged better. I’m obviously not knowingly going to do something that isn’t good or splendid, but I’ll see what I’ve got first after a dry build. There is no agreement here yet anyway, which isn’t surprising as we only have half the story. I will add that the ports on the DR are not single, square-edged ports; there are several extra ports, and some of them are sloped which would make getting an even edge more difficult to achieve; I’ll do a mark up of my port rubbing below to show what I mean. · I reckon there’s no harm in doing a ‘dry’ build with the bearings I have and crank, piston and barrel; unless you reckon it is too inaccurate with old bearings? If it isn’t worth it then I’ll leave it until later. I want to have a look at the old seal there anyway - thanks for info on that bit vespasco. · I’ll do the extra volume measurements of the barrel and head, as described, and anything else, measuring/calcs wise I can do for now. · I’ll take some time to look at these other bits of software; I have Tom’s Tuning Tools on this computer, but only really got into the Dyno stuff. There’s also that big spreadsheet I linked to before, which I haven’t really looked at yet. · I’ll continue looking for the parts that will enable me to put my cases together, and make sure I have all the new parts I need too. Vespasco, I have taken note about your driveshaft, and I’m grateful; I know you may have or had other plans for it – I’m also still looking elsewhere and we’ll have to see how that develops too (I might have some good news after the weekend on that – got a chappy shed-scroffling for stuff). Getting something I’m going to be happy to close my casings around and be confident about long-term is still a problem I haven’t sorted. · I need to pluck up the courage to cut the crank inlet, and I need to establish whether the crank cutting is Dremmelling (by me) or Grinding (on a bench grinder, which I don’t have). I need to watch some videos and make sure I have the right equipment too. · I need to buy some cutting stuff, and some stuff to do the volume measuring. · I’m going to make my mind up about this crank puller, and buy it if I need it. · I need to look at the casings and barrel transfers, and decide what needs doing there. · I need to tidy up the head and measure it. As far as ‘finding out how accurate I can be’ – I don’t think I can even see well enough to be sure how accurate I am being! Here’s the barrel rubbing, marked-up to show the channels inside the sleeve, rather than just at the face; there are very few square edges, which makes measuring and cutting pretty imprecise: Thanks for the advice chaps; plenty to be investigating and getting on with – happy days! Just an afterthought; I won't be doing anything else on it today, it's all back in the box, here's what I meant about not having 3mm to take off the top of the barrel - there's only 1.5mm max if I understood what you meant (I'll look at the head more closely over the weekend):
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