|
Post by henri on Apr 28, 2015 18:43:13 GMT
on my polini engine i think ive a mazzy crank , think, from re-reading simes build posts theres a mazzy crank spec,page 3 or 4 , anyways it has inlet timings in a single figure , I.E long face 96 degrees short face 93 degrees , the crank webs differ in length , i'm guessing its this way as they cant know the inlet shape/timing so just do a total, in my cases it works out as 130/50 , traditional way ,not bad for a tourer but with room for improvement , so i'm guessing ive got to measure there duration on 1 side of inlet an find the total an see which mazz crank that matches . figures are just rough so far ,as only had my old/faded/worn degree disc to hand , an only put crank in to see how my sip dummy bearings worked . only used the clutchside today an it makes slippin a crank in to measure a real doddle ,so easy i took it back out an did it again for fun , other rough timings i'm gettin on ports dont add up right so need to be re-done proper , exhaust opens 103 ,inlet opens 130 , exhaust closes 268, all ATDC , as you can see exhaust adds up to more than 360 in total , so disc must of slipped been misread , didnt re do em as was just matching cases to barrel today , somebody had made a start on fly side an then stopped after 2 passes of file by look of it ,prob worried bout breakin through ,got most done ,just needs a tidy up n barrel edges knifing . 1 thing ,my inlet tract is a definite oblong ,no drilling at either end ,so am guessing its been worked , will post piccys n work out cases age tommorrow after my hacks mot , H
|
|
|
Post by vespasco on Apr 29, 2015 17:50:45 GMT
Im not sure what the polini timing should be but 100° transfer timing seems a little low!? I'd have thought they should be closer to 118° for that exhaust duration? ? would make more sense. Hang on, what cc is this kit?
Was the long/short face thing the angle of the cut of the crank web? I cant remember now.
Nice to hear those dummys work nicely. Just dont go throwing them outta yo crib ;D
|
|
|
Post by henri on Apr 30, 2015 8:20:29 GMT
thats my first impression aswell ,100deg just aint enuff , its i think a polini 177 ,well def polini an bores 63mm by eye/ruler , the long /short is the crank webs dont end symetrically by the big end , by simes mazzy data 1's 93degrees of 360 n others 96 , thats the rotation of sealing faces , i need to get the dti/verniers n good degree disc out an measure up accurately ,meant to do it yesterday but had a throttle cable unravel n jam me on full throttle on way to mot .ended up doing 15mph in 2nd uphill holdin it back on brakes stuck behind a loaded hearse n mourners cars screamin at bout 5000rpm . by time i'd got to mot dumped scoot bused back n forth for a cable i'd missed my slot ,had to sit bout 3 hours for nxt one .nearly overdosed on free garage coffee an cheap lidls horse pastys. had a good crack with the mot-ers tho , an had plenty off numptys to point at n laugh . so not a wasted day , oh an yes it passed ,no advisorys so well chuffed . H
|
|
|
Post by pxguru on Apr 30, 2015 9:14:57 GMT
100 degrees TD isn't enough for any type of use......well maybe your Granny riding it to work and back but that's about it. What kind of scooter you want it to be? What exhaust is going on it?
|
|
|
Post by sime66 on Apr 30, 2015 9:57:14 GMT
At the risk of looking foolish, I’m going to ask some basic questions because I don’t see where you’ve picked up this transfer timing of 100 from what H has written so far. This is what I think H has said so far (ignoring the 'slipped disc' error; I'll tweak it if it helps anyone else; - it helps me picture it): This is our little table for exhaust Vs transfer Vs blowdown timings: Isn’t it just a case of increasing the exhaust timing to then get the transfer timing right for the desired revs like vespasco and I did? I’ve got a feeling I’m missing something obvious, but I’ll risk it with this little post. (Is the “ inlet opens 130” in the first post a typo? Did you mean transfer opens 130? – is that the bit I’m missing - 360-(2x130)=100) [EDIT: reckon I've answered this for myself now, so we just need the right/accurate measurements] AND - while we're on the subject of posts that might be deleted after they've caught the interest - vespasco; what happened to your post the other day in H's "Atomiser Codes" thread; that's another one that got me going, and when I went back to re-read it had disappeared (lovely little drawing and everything).................?
|
|
|
Post by sime66 on Apr 30, 2015 10:17:58 GMT
This is the crank stuff from my post: 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.This was my best guess of the Mazzy crank timing I decided I didn’t want to use:
|
|
|
Post by henri on Apr 30, 2015 15:29:39 GMT
yep sorry sime that should of read transfers open at 130 , so unless ive mis-read my faded dial really badly reckon its a real flat engine , that was with the thinnest base gasket tho, they go up to 8mm packers from sip ,soon as i'm home the dti's comin out an some proper measurements taken ,in meantime i'm going to research the worb5 specs , i dont want to widen the exhaust anymore as it looks on the limit already without goin thin ring , but raisin top n droppin bottom seems to be on the cards , as well as raising transfers , pxguru whats the min transfer duration for a tourer you reckon , H
|
|
|
Post by henri on Apr 30, 2015 15:34:17 GMT
oh an the exhaust that was on it was a mallosi down n forrad , so ive a choice between that an a sterling st/steel 1 or buy a sip road2 , H
|
|
|
Post by vespasco on Apr 30, 2015 20:18:47 GMT
Dremel Fever is spreading If those timings were correct you'd need to raise the trans for sure. Not sure about the exhaust until you measure it again. Looks better than transfers anyway. I was blindly presuming it was 125/150 kit to start with but then looking at those figures it seemed more like....a... ...lawn mower!??! You need to have a re measure. If youve found your deck height or BDC you could probably measure all the ports with a small set of verniers and work it out from there. Ah yes! That Atomizer post. Ahem! Id been re-jetting lately so while i was there i tried all my different mixers, just for fun, took some notes, I wrote it out, pasted in the links for pics, posted it, read it, edited it read it again, looked at my notes, read it again, then realised it was wrong! I'll repost it soon enough. Busy! Busy! Roughly, it was showing which parts of the mixer feeds the venturi with what And a quick look chart of the holes in the mixer and what they do Henri, Id be having a look at somewhere near Simes timings for your similar sized kit/set up. Polinis can be quite Torquay, you need to keep the torques for a tourer. So a pipe with lower down/all round torquey-ness would be a good choice. But depends what you mean by touring! Haha! Getting there as fast as possible or managing to keep it @ cruising speed uphill in headwinds without suffering any performance. Is it ali or cast ironIc?
|
|
|
Post by sime66 on May 1, 2015 6:46:42 GMT
Polinis can be quite TorquayMy DR is good for Torquay; in fact I can go quite a lot further along the coast than that! (Sorry, but it is Friday – the weekend starts here……..) That Atomizer post. Ahem!I was starting to think you had your rich/lean muddled on the blue (air?), but when I went to have a better read and check, it had gone; never mind. I think the barrel in question is the suspected Pollini 177 from this thread, isn’t it H?: vespa.proboards.com/thread/4812/groove-machined-crank-webSo what we need is some proper port measuring doing, so we can see what’s to be done to get some decent timings…………… Also, it occurred to me that the 130/50 doesn’t sound like a Mazzi crank. Only from what I found out before, but the ATDC would be more like 70-75, obviously depending on your crankcase sealing pad, but in that region from what Alex at Scootercentre said when I emailed him. I went on from there to decide that those extra ATDC degrees were not what I wanted for a touring set-up, but with a tweak the crank you have would be. As well as the inlet timing with that crank, do we need the actual degrees on the pad to see what the timing on the crank is, and if it can be tweaked? And some photos!!! But what do I know; I'm only a learner..........................................
|
|
|
Post by henri on May 1, 2015 9:19:02 GMT
yep its the iron barrel polini kit , an the inlet timings are the only accurate ones i took , trying to suss out what works been done to the cases , there a non electric start px 125 cases ,a px125e i believe ,meant to stick numbers thru scooterhelp.com but forgot to write em down before leaving home .the inlet shape is a rounded corner rectangle ,n looks like it was drilled like your cases originally an has been opened out , those timings where taken from the tract opening on the shorter sealing face ,as i dont know wether thats where you measure from or from the longer one an fully open or even a average between the two, that prob explains the discrepancy between my 130/50 an the 70/75 you give above , vespaco ,by eye n guesttimate my deck heights bout -.6-7mm an squish's lookin around 1.8-1.9 , soon as i'm home its dti n verniers time ,an rather than opening ports out any i'm going to investigate raising the barrel with a packer an shaving the top back off to get correct squish of around 1.5mm , will have to determine how low the rings go at bdc an maybe drop the floor of exhaust port a tad an raise its roof aswell , the worb5 specs says they widen it a mm each side an raise it 2 n drop it 3mm , so probably will copy those specs but not the widening ,i dont want to go into gs /thin ring piston territory , mostly i'm trying to correct/improve on the work already done without great expense ,an sime your not a apprentice/learner no more , i think its more appropriate to say your a "journeyman" now , not a master of the trade yet but gettin there , unless your learner crack was a ref to the "leper plates" your scoot displays , H
|
|
|
Post by vespasco on May 1, 2015 16:18:33 GMT
If you want to avoid spending your $$$ id start off with a stock gasket, which hopefully will give a nice deck height and squish, without the need for any skimming to the head. (Ive not seen the polini so dont know if thats do-able) Have a look at piston crown @ BDC. Is it level with the bottom of the ports? If it isnt, what work would need doing? If its not much, go on, get the dremel out Once you raise the ports to suit what it is yoh want, theyll not likely be any need to widen them? I think all the inlet cases are drilled. 200 has a hole at the 'front' for more advanced inlet closing, 125\150 has the inlet drilled at the 'rear'. I also use the centre line of the crank web as a measuring point for a reference point.
|
|
|
Post by vespasco on May 1, 2015 16:44:00 GMT
Mixers: I actually got the low/mid rpm confused with high rpm Decks: Yes its the weekend!! Lets get the party started ... Party:
|
|
|
Post by pxguru on May 1, 2015 17:35:40 GMT
H, If the crank is opening a respectable 130/50. Then the TD will be better a bit lower, maybe 120. If yours is 130/75 then its a full racing crank (205 degrees) and will need to be let loose with at least 128 degrees.
|
|
|
Post by sime66 on May 1, 2015 18:59:04 GMT
vespasco, your link don't work, was it something Weekendy? I did have a couple for you as it happens, not weekendy really, but maybe worth a listen, so I've stuck them on the Musical Wanderings thread: vespa.proboards.com/thread/4747/musical-wanderings
|
|
|
Post by vespasco on May 1, 2015 20:04:07 GMT
Link sorted Have a great weekend
|
|
|
Post by sime66 on May 1, 2015 20:34:57 GMT
Oh yes; that's made me smile - King Short Shirt into the collection....... Good weekend coming up - double birthdays May 2nd and 3rd = busy, fun times. Happy days have a good weekend all
|
|
|
Post by henri on May 2, 2015 10:00:32 GMT
you beggars ,was goin to have a slow/easy day n stay out the shed , but king short shirt/the prince has inspired me , an a new selecter album coming soon , out of the dressing gown/joggers into some oily rags an shed bound am i , get some tunes on an chase the hangover away with some argon n sparks , happy days to 1 n all , H
|
|
|
Post by henri on May 5, 2015 18:40:50 GMT
got some better figures today , exhaust opens 95 ,closes 265 ,duration 170 , transfers open 123 ,closes 237 , duration 114 , (still low) 28degree blow-down inlet still 130/50 , am thinking inlets been opened an crank cut , with a 57mm stroke an minus a degree each for tdc n bdc thats 358/114 =.31843575 mm of travel per degree rotation(roughly) , sip do base gaskets from stock .6 right up to 8mm , a 1mm gets me a extra 6 degrees duration an a adjustable squish still with head skimming rather than barrel mods ,an a mill of top n bottom edge of ports is same as worb5 spec , except worb widens exhaust aswell but thats thin ring territory . am tempted to gas flow an put back as stock?, an try this mycro dyno thingy an then space by a mm an see where that takes me . tho with those inlet timings an the mark on crank might be better either saving for a reed block manifold , or trying to see if theres the space for a lml reed block ive got in the shed already , H
|
|
|
Post by vespasco on May 5, 2015 19:15:49 GMT
I can only imagine from your previous descriptions that the crank was been worked and the inlet has been opened at the 'rear'? It opens very early for your set up. Raising the transfers only, by around 1.5mm looks much better @ just below 123° The exhaust looks ok at 170°. id leave that personally. But i'm not sure how the ports look @ BDC against the top of the piston with a stock 0.2mm gasket? If thats good already then that leaves your squish and deck at a good usable height and no cylinder skimming required!
|
|
|
Post by henri on May 6, 2015 6:46:37 GMT
the deck at bdc is exactly level with bottom of ports , i did think about just raising transfers ,but unless the exhaust is raised aswell would cut my blow down to bout 24deg , still usable an i guess wouldnt alter my swept volume any saving more maths/work. reckon i might go with that suggestion . after all the engine was pretty naughty with unmatched barrel/cases an a shot clutch side seal, bit all or nothing tho, but i'm told thats quite likely the mallosi pipes effect , H
|
|
|
Post by sime66 on May 6, 2015 12:55:57 GMT
I have to do my little diagram to make the numbers mean something, whereas you chaps see stuff straight away from it. I’ve only got what I’m learning on mine to go on, not years of different engines across your workbenches, but I can see that the transfers need raising, and not the exhaust especially; I see that if you raise the transfers more than 6° you’ll be outside the 10° overlap between Io and Tc because of the early (130°) Io you have – but that 10° was a guide figure from my thread, not sure how strict it is. It looks like 120° TD would still be low anyway, even with the extra 6° TD – for the 170°ED and 28°BD (that’s high BD isn’t it?). Also would only 50° Ic ATDC be poor higher RPM power too? That might be nonsense, but I’m trying to keep up, follow what you’re considering for changes, and hopefully apply some of what I might have learnt to see if I have learnt anything. If it’s nonsense, I’ll just go back to following quietly……………
|
|
|
Post by henri on May 6, 2015 15:14:40 GMT
nah, all makin sense to me sime, as vespaco said a 1mm transfers rise would get me in the ballpark ,bout 120 degree ,would like to go 1.5 like he suggested but as you said its starting to conflict with the crazy inlet timings . heres where i want to be rich n scrap that crank ,lose the sealing pad n throw on a reed/full circle crank. have to finish the spacer block for lml reed this weekend an check clearances to body work with a 24mm phbl dell' , if it will work might open out the inlet to compensate for reed restrictions an not worry so much bout spit back n conflicts . also leaving the exhaust like vesp's suggests an raising transfers would drop blowdown to more like 25 degrees , better at high rpm but less torque at low rpm , Aaarggh ,i remember why now i stopped tuning , the vice/versa ,knockon effects ,do this an then that needs this , it twists my poor noodle , H
|
|
|
Post by sime66 on May 6, 2015 17:09:25 GMT
I’ll carry on until I do say something silly then, which might be any minute now………….. Overlooking the Inlet timing for the moment, because you’re considering ditching the whole thing, and it’s that ‘old-groovy’ job anyway, isn’t it? With just a raising of the Transfer timing to 122° (4° both sides), you’d have exhaust still at 170°, and blowdown then at 24°, so: TD=122° ED=170° BD=24° That’s near to the figures for 7,000rpm from our little table before (and a cheap and cheerful sort-out; quick bit of measuring and dremelling for a man of your calibre). I’m not following why your BD is a problem – that table says BD of 28° is nearer right up high in 8,000s, (mines 25°); here’s the table again: (My numbers: 7,500 TD=122.95 ED=172.58 BD=24.81) I read that table as there only being a problem with your figures for BD when you go above 122° TD? If you went to 123° (4.5° both sides) - 7,500rpm, you’d have: TD=123° ED=170° BD=23.5° That’s pretty close to good as well isn’t it? With proper measuring to decide exactly where to aim for when proper, exact mms. are known. I’m also wondering how that fits in with what pxguru said on this thread on may 1st: “If the crank is opening a respectable 130/50. Then the TD will be better a bit lower, maybe 120.”And on an old thread on October 30th last year: “The point of this thread, is that the number one priority when fitting any new barrel to any new engine is to have the transfer degrees set to where they should be”.vespa.proboards.com/thread/4487/cranks-thick-gaskets-squish-timings?page=2(I know it isn’t a new barrel, but the point is to start with TD). So, what you gonna set your TD at, H? Could you get decent Inlet timings with your casings as they are and just an unchopped crank, and then increase your TD?
|
|
|
Post by vespasco on May 6, 2015 17:30:34 GMT
You could drop the BD (just by raising the transfers) to nearer 24°, even 23°! and youd still be near the 'centre' of the ball park with your existing exhaust duration 28° is too much for that tiny transfer duration. Yes it would make a bigger overlap on the the inlet opening/trans closing but i was thinking youd be getting a new crank anyway. You could put the money youd save on skimming towards a crank with suitable inlet timing for your case inlet, what ever that is? (Im guessing the case inlet has been cut right back to open earlier. If so, with a mazzy race crank (or similar timied crank @ 127°/7°) id guess you timings would be pretty good...around 123°/57° (roughly) Id hazzard a guess the case inlet was opened to suit a mazzy crank, then later swapped out for that weird crank you have?? I dont think youll get much blow back with your current timings. you have like 40° in between exhaust opening/inlet closing Hhmm reed valve!! Better carbs, better and more fuel flow, even less chance of blow back. And if youre gonna make use of your pipes you mentioned then youd need something that is able to rev a little bit!?!
|
|
|
Post by henri on May 7, 2015 8:58:10 GMT
aswell as wanting a less revvy engine ,as vespaco above says 28's too much for transfers that are blinking open so little , i'm not sure on keeping the mallosi pipe as its a bit all or nothin , an makes a centre stand a no-go on a smallie , thanks for ya answers lads its helped me decide , raise transfers ,alter squish by base gasket/spacers ,an leave rest alone for now , theres too many variables for my brain at the moment ,i need to run it an let "seat of my pants" decide further , i purged all this stuff from my brain years ago an its hurting to try n re-learn , that n a tad embarrasing that simes just learnt it an has a better grasp than me , must be all them fancy graphics he runs , as i cant seem to hold the info/pictures in my head anymore , other stuff life/work/play/money n beer seem to get in the way somehow .H
|
|
|
Post by sime66 on May 7, 2015 10:24:18 GMT
No amount of me learning now, will catch up with your experience though, H. When you posted your last measurements on May 5th, vespasco replied before I even understood it; by the time I'd sloped off and done my little drawing and had a re-read of previous stuff, he'd worked it out from just the numbers, and you two are talking a language that I have to translate into pictures - (I can't picture it without a drawing), and referring back to tables and previous posts from you clever blokes with stuff already well-lodged in your heads for years. When you all go dirty-hands-on, seat-of-pants I'm squirrelling away on the quiet to keep up!
So, I'm looking forward to seeing what you do, seat-of-the-pants and hoping to follow as you go................
(We'll get you on the MicroDyno when you're done though; I think you mentioned it recently)
|
|
|
Post by henri on May 7, 2015 16:32:34 GMT
microdyno, HHmmmmm , have thought bout it ,would be cheaper than a run to littlehampton an goin on a dyno, or runnin up the old A3 from my pops,my usual test run , its dual carriage thats been made single so loads of room for run-offs/escapes , an slightly uphill for 3 miles , good for WOT's , an has a nice pub car park at turn round point ,an a vintage bentley garage at half way , get sum funny looks if ya pull in an do a plug chop there , H
|
|
|
Post by vespasco on May 7, 2015 16:52:35 GMT
I wouldnt rely on the Microdyno too much to fine tune H..unless you have the use of a rolling road Its ok but i bet, with your experience, seat of the pants would better. Its good to use once your motor is set up...more for future reference/ to compare any changes. Id like to use my MD at a proper dyno place. Compare the two. I dont think it will be far out on a rolling road.
|
|