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Post by sime66 on Jul 11, 2016 12:22:53 GMT
I’ve been thinking about this for a week or so, but not done much about it; I do have a bit of tweak-fatigue at the moment, and TBH, a bit of a quandary that I can’t really get enthusiastic about getting out and sorting, so I’m picking brains whilst I sort myself out a plan of action that I can get enthusiastic about. I’m quite enjoying my cycling at the moment; instead of long trousers, gloves, boots and helmet in the Summer, and fannying about with this bleedin’ engine all the time.
It boils down to the fact that I’m getting high CHT temps, but not a particularly lean plug.
Sequence of events, without all the specific measurements and photos, although I have them, (but cannot currently be arsed): As planned I was working on my MJ, going smaller and leaner and seeing improvements as I went to 130mj. At the same time I was waiting for, then fixing, the new CHT sensor. With a decent, but not digestive, 130mj, I tried the 128mj but that looked richer, so thought it might be a dodgy jet. Meanwhile the new sensor (on the plug again) gave me a reading of 15°C (no longer –24°C) when ambient was recorded as 15°C, so that was very encouraging that CHT was fixed. I had a 127mj so tried that (and had the CHT working by this time) – the gauge went up to 150°C before I’d even got out of the first lanes! – rejecting 127mj I put the 130mj back – up to 150°C again – I pulled the choke and came home – covered it up in disgust, and left it in the naughty corner of the garden……
I see several possibilities, which I’m trying to put in order of likelihood, and ease of checking: My CHT may still be wrong, I can check it with boiling water – BUT I won’t just disregard it, so I reject that suggestion before it’s made. I may have an air leak, but it’s starting well hot and cold, and the plug doesn’t look lean, nor is it high-revving. I am pretty confident my crank seal is good; it’s running fine by feel and the fuel was great when I changed it during the top-end revamp. My reduced squish may be giving me too-high compression and heat that is either noticeably higher, or just plain too-high (my squish is now 1.15mm, but I haven’t re-done the calcs to check compression ratios). Maybe these new, higher running CHT temps are actually more accurate now that my ambient CHT (cold engine) is correct, but too high? But don't think it's jetting. Maybe is it squish/compression or something else?…………..(this is where I need to check stuff and decide/seek advice) Maybe Summer ambient cooling air temps are going to be a problem? Maybe something else, not yet considered, was damaged during the seize. Old/damaged/worn rings?
This is roughly what I intend to do: Check plug to see if it shows any temp band as well as colour (but I haven’t done any long runs because of temp going up so quick, nor do I really intend to at present – (if I’m seeing 150°C up the lane then something is wrong, and going on a long run to see how bad it is doesn’t seem wise) Retorque head. Retorque carb – go back to start-after-seize jetting (48/160 and 135mj) to see if temp drops. Blow-through jets (Remove carb and blow-through channels). Stick a big mj in and set up Pilot properly, and do progression temps/chops - there's several previous known-good set-ups too. Check exhaust stub. Check CHT with boiling water Do my compression ratio calcs to see if I’m too high now. (Put 0.2mm spacer back to see if it resolves it. (I haven’t really had a chance to get an impression of 4th now, but I’m missing the nippiness I had before*, so I’m quite happy to put it back).
As far as running is concerned; it feels fine but like it just needs jetting properly* (rich, not lean), which plugs confirm, and which it does because that’s what I was doing before this cropped-up. It doesn’t feel like it’s going mad with an air leak, or any problem starting. That suggests that CHT is wrong, but I’m not prepared to just ignore it.
I sort of know what I need to do; I’m just picking brains really and trying to get in the mood again to try to sort it – any suggestions/other things to consider/possibilities to reject? No hurry; I’m not rushing out to it – she’s in the doghouse and I’m busy anyway (this is first chance I’ve had to gather thoughts and type them out)…………
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Post by pxguru on Jul 12, 2016 4:58:01 GMT
Was wondering what you were doing. I am sure it will run like before once jetting is better. Compression is not too high; The tighter the squish the less risk of pinking. On a 177 less than 1.0mm is the target if you were looking for speed. The seize didn't damage anything, I wouldn't have even took it apart, just ran it and it would have sorted itself out.
Sometimes when really way too rich the CHT can go up as the burn is much longer and slower. Believe what the plug says. The new sensor could be reading a little higher than the old too.
With the AC160 BE3 04 slide & vortex fixed, there are only 2 variables left. MJ and pilot. Without all the extra air holes there will be more draw on the MJ so it will end up smaller than before. The MJ needs to be set from plug colour at WOT. As you said stick in a big MJ, if you put in the 135 to get your confidence back then do some long WOT riding in 2nd and 3rd. It shouldn't take too many plug chops to set the MJ. I guess 128/130/132 Then set the pilot jet to the weakest one that doesn't flat spot at progression. That should then be it.
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Post by sime66 on Jul 12, 2016 18:54:13 GMT
All taken on board, thanks. Pretty much what I was doing, but I’ll forget about the squish/compression/rings; probably still give the nuts a tweak though. Plug is OK – I had a look when I put the richer jetting back this morning; it does seem that it’s actually the CHT gauge is reading high now for some reason, but I’m still reluctant to disregard it. I’ll see how it goes, but WOTing when my gauge is telling me not to, will obviously be approached with caution……………
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Post by vespasco on Jul 13, 2016 20:10:22 GMT
yeh. believe the plug the cht gauge readings are just numbers for me. once youre happy its running well at WOT etc then set your bench mark on the cht gauge. And its a new gauge, different/correct ambient temp readings, slightly more compression too..all could add a few more degrees.
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Post by sime66 on Jul 13, 2016 21:17:08 GMT
I still ain’t getting a lot of riding done lately, but I am more relaxed about it the more I think about it, I did have a bit of a thought this evening too, which cheered me a bit; a theory that I’ll put to the test over the weekend (I know I’m the only one worrying about this CHT reading, but it’s my bleedin’ engine we’re talking about, and I’ve already broken it once, so you’ll excuse my caution). It occurred to me that, as well as it being a new sensor that’s now reading correct ambient with a cold engine, I’ve relocated it a tad to make it less prone to being bashed about by plug removal; I’ve sort of wedged it between the fins, and downwind of the plug – I could well have created a bit of a hot, still air pocket there, and the sensor tube might be close to a hot fin too, rather than in the airstream; it’s also nearer the centre of the combustion chamber now, rather than the edge of it. – That theory will be pretty easy to confirm or reject. I will be far happier to get back to giving it some beans when I’ve explained why I have the higher readings; I don’t dispute that it’s just a number, but I want to know why this number is suddenly so much higher than the number I was happy with; I think that’s sensible. I’m sure it will turn out to be to do with the CHT sensor/gauge, especially as the plug is OK, but it’s also just possible that the cause of the seize is still a problem, or that I’ve created a new one when I put it back together. This photo might explain what I mean; I was playing with a spare head and the old ring to see if my theory might be feasible:
And although this became a cautious ride home, so not a very worthwhile plug, I think it pretty-much confirms that nothing alarming was going on when I last went out and the CHT gauge shot up:
Remebering that I was having trouble getting my Progression temps up also suggests that my previous gauge was reading low, rather than this one reading high, so it isn't certain that this one is wrong now; also suggesting that the old one was low, is the previous comment that I didn't do all the damage in just the one seize. I don't need to jump to any cnclusions; certainly not just concluding that I should ignore these high readings.
I’ll just do me fiddling and thinking in my own time, and when I’m happy that I can understand why it’s doing what it’s doing (probably a combination of things), I’ll start dropping the main again; I’m in no real hurry and pretty busy at the moment anyway. - Still approaching with caution...........
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Post by pxguru on Jul 14, 2016 6:55:06 GMT
Plug looks like its doing 50 miles to the gallon, so plenty over rich. And the not so good performance confirms it. If you have the CHT out of the airflow, it won't read the same as before. I tried mine on a stud for a while and the readings dropped so much (at least 50 degrees) it was a waste of time, so put it back on the plug.
If the readings are going up so fast, whilst not at WOT, put in a bigger pilot. Maybe 50/160.
Really overrich does seem to make heat too, possibly something to do with the extra engergy dissapation during compression of the heavy mixture. I have seen this before on some of mine. Believe the plug.
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Post by sime66 on Jul 25, 2016 10:55:36 GMT
Spurred on a bit by pxguru’s 200 Tourer update, but still not convinced that my CHT gauge was wrong, giving me 145°C with a silly little Saturday morning trip to the shops from an ambient of 17°C with richer jetting, I had a quick look at my plug this morning, with a view to torquing my head and carb at the same time if it looked like it might need it. Low and behold three cylinder nuts clicked the torque wrench nicely, and the fourth gripped and slipped on the stud – stripped thread. I bought these studs from Beedspeed because, at the time, I wanted DR rings too, and only Beedspeed had those in stock (this was after the seize, when I was trying to get it sorted and back on the road quickly); I had heard that they were poor quality from Beedspeed and I think I can reinforce that opinion now. As it happens, at the time I needed some stuff from Wasp as well, so got more studs from them (as part of my making sure I get my monies-worth from postage costs and building up my spares), so this morning I’ve replaced my studs with the spare, new Piaggio-bagged ones from Wasp and used all new washers, spring washers, and nuts. I checked my carb bolts and exhaust stud too, which were fine. Next time I get up early enough I’ll have a blast to see if it’s made any difference. I know you chaps have said not to worry about the temps, and I didn’t want to ignore your advice or go into one of our circular discussions with no progress either way, so decided to stop arguing and sort it out myself in my own time, and I haven’t been happy trying to get any WOT plugs when my CHT gauge is telling me there’s a problem; I felt the advice ‘believe the plug’ was missing the point I was trying to make. Hopefully this will be a bit of a breakthrough now. This is only a plug from a Saturday morning shopping trip (probably no more than 90-100kph indicated on speedo, not GPS), but I’d say it’s too lean for 48/160 & 135mj (when I’d expected that to be rich and show a drop in temps and from there wanted to do some WOTs and downjet); hence my further investigation: (This should have been noticeably richer and cooler than plug above)
This is just an update really; if the stud/head overhaul doesn’t improve things I’ll take previous advice and go 50/160 before dropping main, but I’m going to get to the bottom of the CHT temps before I do any WOT plugs no matter how many times I read ‘believe the plug’. I’m really not spending too much time faffing about with it at the moment, or taking the jetting tweaks too seriously while it’s so warm anyway; too busy, too hot and bothered, too apathetic.
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Post by pxguru on Jul 25, 2016 18:11:19 GMT
Do you have some of those thicker 7mm nuts? They will definately be less prone to stripping. www.sip-scootershop.com/en/products/nut+m7x1+mm+nickel+plated+h+70mm_87170000Plug looks pretty close. It looks one jet size bigger than a seize. The 138 MJ might be too much though. I would think that upping the pilot will make enough differance to slightly darken this plug. If you have no flat spots or spluttering through the revs then the BE3 and AC160 are fine for yours too. Hard to say when not actually riding it but it seems like it is warming up too fast. If you start with a 50/140 or 52/160 pilot it might be slightly too rich at progression but it might not be. You are looking for one jet less than too rich. A couple more fiddles then its all done
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Post by sime66 on Jul 25, 2016 20:04:58 GMT
I did buy some deeper nuts before with the same Beedsped order: www.beedspeed.com/fastener-deep-type-p-12506.htmlBut they were so shabby, and actually loose on their chocolate studs too, that I didn’t use them. I did think they were a good idea and I’ll get some real ones next time I order something. Don’t worry about this too much because next run I’ll hopefully have a more sensible plug to work with, but I think you’ve missed my point about that last plug above; that is a plug after I’d upjetted to try to get the temp down; I expected it to be rich and the temp lower, but it was just as hot and came out lean – that’s why I went on to do the head and found the stripped thread; it’s before I changed the studs, so doesn’t count as a plug to read now, other than to show that it might well have been a head leak giving me the temps that were bothering me. Now I’ve fixed that I hope to get sensible temps that will enable me to do more of a ride and get a decent plug to work from. I hope/expect now that next time that’ll be the case, and possibly the 48/160 and especially the 135 will be rich; I didn’t change them today because I want to do a comparison to make sure it's improved. I’ve noted what you said before and here about Pilot possibly making my temps go up too quick, which does make sense to me; initially I wasn’t convinced because of all the careful work I did before on the Pilot/Progression plugs and temps, but I think that was before the vortex, so it isn’t that unlikely that I might need a richer Pilot now. If a lean Pilot would have made it noticeably livelier though, I can’t say I’ve noticed that. I’ve noted your jet suggestions there. (Just for interest, not sure there is a 52/160; don’t see one listed anywhere, or on my table, or even in my magic box of goodies). Anyway; time isn’t pressing now, so I can work it out at my leisure without making any changes until I’m happy I’m going the right way, and not getting too close; ‘one jet size bigger than a seize’ when the weather is so warm is not OK with me, but I think you didn’t realise why I was showing that plug that you based your observation on. It’s actually been starting well and riding fine (apart from temp) – I can’t explain the good starting if I had a head leak, but maybe it’s running fine because it was overjetted with a bit of a leak. I do still acknowledge that the CHT may just be wrong, but if it is I will have to convince myself of that before there’s any more hooning up the motorway…………………. It isn’t far off, as you say, and I haven’t noticed any flat spots, so I’m optimistic about just BE3 and AC160 being good; these other tweaks can take as long as they take – during which time the weather might well be 10°C lower, which might shed some light on it too. It’s a bit of a mystery, but not bothering me too much at present.
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Post by pxguru on Jul 26, 2016 8:47:22 GMT
I would never fit anything but genuine barrel studs. And once they are in. Never take them out for anything but a major reason.
I see what you are saying about the air leak but it is still close jetting wise.
If the pilot has not been done since the Vortex was fitted it really should be. Without changing the main jet up the pilot until you can feel it is too rich when riding along. Should get an uncomfortable splutter somewhere between 1/8 and 1/4 throttle. Then fit a slightly weaker jet and its done.
Once the air leak is fixed and pilot upped then that could be it......until the Winter
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Post by sime66 on Jul 26, 2016 9:51:45 GMT
This (-below-) is what I expected to see with that jetting (same jetting as above, but after stud repair), so it seems to confirm that I had a head leak:
I wanted it to be too rich because it now gives me a plug to work from. I think that 48/160 Pilot is pretty close though; I did set it up in the lane with mix and idle, a smooth Progression, and starting is good hot and cold, but will go through it again and change and tweak either way to get that right before moving on (idle-rev-idle, smooth low revs and progression plug). The Pilot has been done many times since the vortex, but never with the same care as those first sessions in the lane and Progression plug chops, which (without a reliable CHT gauge) I will do again now properly – I was doing Progression temps.
That main is obviously too big as well, which I expected, so I’ll do that when I’m sure the Pilot is right; this will also give me some more confidence that the CHT gauge is now wrong; because I’ll be doing Progression before worrying about risky WOTs. What I do about the CHT is another matter; I don’t want to ignore it, but it’s an arse and an expense to sort it.
Yes - I am now becoming more convinced that the CHT gauge is wrong; I got 155°C from a short run with an ambient of 16°C this morning, and giving that (^^) rich plug, so the gauge is obviously not telling me what the engine is doing. I’m coming to that conclusion reluctantly and carefully, but it does seem to be the case. It means that my next steps will be careful and in my own time; I will be riding with my gauge telling me it’s too hot to continue! I’m going to do the Pilot then the main, as we did it the first time, and as seems much more logical than what we’ve been doing since the seize. I'll worry about the atomiser afterwards, if necessary.
I had previously noted well, and followed your advice, to get the studs in and leave them alone, threadlocked in the precious casings; it is advice I had heeded, which made it all the more of a b'stard to get the freshly-threadlocked chocolate ones out yesterday morning!! When I did Old Faithful, I used a pretty expensive set from SIP. Anyway, now I have genuine studs, and it’s another lesson learnt, which I pretty much knew anyway: – Buy from Beedspeed, buy twice!!
Summary: · I think I had an air leak at the head, which is now fixed. · I think my CHT gauge is telling me whoppers, so will proceed carefully without too much reference to it. · I have an obviously rich plug that proves the CHT is wrong, and that I trust to use for my jetting tweaks, and I’m starting carefully with the Pilot. · I will be keeping it on the rich-side of careful now, rather than taking any more risks for performance that I don’t really care about at the moment; it’s still very warm ambient now anyway, and I’ll be riding muffs-on at near-zero early mornings again in September, which is only 4-6 weeks away, so this now is not bothering me too much; even with this rich jetting, which I will tweak, she’s riding fine enough for me for a bit, and it will need a proper session when the weather cools anyway.
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Post by vespasco on Jul 26, 2016 18:00:21 GMT
So long as the CHT gauge is consistent it should be a useful guide if temps suddenly spike... i think that's the best thing we can use them for.
Forgive me if it's been mentioned already, you know what my memory is like, have you considered an EGT gauge? I've never used one personally but would one of those give more useful readings?
Don't worry about the weather, the sun is here right up until I jump on a plane again ;D
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Post by sime66 on Jul 27, 2016 7:56:29 GMT
So long as the CHT gauge is consistent it should be a useful guide if temps suddenly spike... i think that's the best thing we can use them for. I needed to convince myself it was wrong before I accepted I could disregard it; that’s common sense to me, but I think I’ve achieved that now, so can proceed. Logically; it’s already let me down because it was reading low when I seized (see EGT point below), so I should rip the fecker out, but I’ve got used to it, so now I’ll have to adjust to its limitations (just odd behaviour) – no problem. I’ve got all sorts of bits and pieces to have a go at making some when I’m in the mood, but I’m not in the mood at the moment, and maybe I’ve lost faith in them a bit anyway. I’m satisfied the recent problem is the gauge, not the scooter; that’s what’s important. Forgive me if it's been mentioned already, you know what my memory is like, have you considered an EGT gauge? I've never used one personally but would one of those give more useful readings?What I’ve considered for next Summer, is keeping it all much more safe and simple, and getting it jetted sensible ASAP after the last Spring frosts, knowing that for me safe is better than 5-10kph more, and no more fannying about all year! Seriously though, we’ve touched on EGT a few times haven’t we; nice idea, complete the picture with CHT (probably would have given me a better warning than CHT did), probably OTT for me really, and anyway I’d have to pay a welder and it’ll only last as long as the pipe and I couldn’t swap pipes without faff – so I don’t see it any time soon - especially as I'm feeling inclined to go simpler rather than more gadgetry. Might go back to having it look plain and standard and showing its age (which it's gonna do anyway living in my garden), but still keep the engine tippity tip-top inside. Don't worry about the weather, the sun is here right up until I jump on a plane again ;DUnfinished business is there? I’m sure you’ll spill the beans about your next adventure when you’re ready. Must be good money in windows, or you’ve been working really hard, to be jetting off again so soon. I might well be getting a one-way ticket elsewhere sometime soon, but I’ll wait until it’s Spring there; Christmas on the beach again - lovely jubbly……..
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Post by henri on Jul 27, 2016 8:25:05 GMT
dont do it sime ,the beers crap in oz . the advantage of egt's over cht is quicker responses an a truer picture of what the mixtures doing . an just to throw another tuppence in the "wishing well" , dont forget a engine set up in high summer right on edge of lean will be other side of the line come winter .H
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Post by sime66 on Jul 27, 2016 8:32:57 GMT
NZ, not OZ - and haven't touched a drop for many years! There's a good discussion "EGT - CHT" to be had; maybe a winter topic if anyone's here. (I've got a piston diagnosis one up me sleeve too) Re: Summer temps; exactly! - Hence my apparent 'cannot-currently-be-arsed' (too much) approach to continued carb tweaks! 'tis summer, bouy
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Post by pxguru on Jul 27, 2016 15:53:34 GMT
Once set up right EGT is pointless but it is interesting. Jetting looking rich now. If you make sure the pilot is slightly rich and running smoothly before reducing the main it will be done on no time.
Will be fiddling with the tourer again this weekend. But riding it in the sun too!
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Post by sime66 on Jul 27, 2016 17:15:58 GMT
....that wasn't a very long EGT discussion Yep; make sure Pilots good/slightly rich first, then drop the main again now I know I don't have to worry about gauge. She's all good now...... Sunshine, seaside and ice cream all the way now (except someone left the gate open and let all the bleedin' Emmets in again)
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Post by sime66 on Aug 4, 2016 15:30:52 GMT
Very briefly; (we've heard that before) I'm hobbling around at home with a broken toe, so, with time on my hands, I picked-up on what you said in your thread pxguru, and went back to look at my last good, safe set up before; and the tripple-whammy that caused the self-inflicted seize. I'm going to put them both here again, just so I can find them again easily; the plan now being to return to the good, safe set up (or something just a bit richer to start safe and check plug - no CHT now) and take it from there. This will mean going back to BE3+2, not BE3 I'm playing with now, or BE2, which I was considering but is quite a bit leaner. I'm slightly incapacitated at present, can't even put a shoe or boot on, and I have MOT after next weekend, so progress might be a week or so away, but it's here when I need it: Previous best safe set up:Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, and.... 48/160 – 45/160 - 42/160 (wound in ¾ turn to 1½**) 140 – 138 - 135BE3 – BE3+1 – BE3+2AC160 – AC170 04(Obstr) – 04 – ? Quick Run Result Summary: 8750rpm (99kph/62.0mph) in 3rd, and 7410rpm (112.5kph/70.4mph) in 4th. – max temp 150°C* *(I see 150°C on the film @ 7310rpm 4th & 137°C @ 7410rpm (cooler, higher = √), but CHT saved max 141°C, so unsure). **Pilot check list: 1) It will start first kick when it is hot after it has been stopped for 5 minutes. YES 2) When closing throttle from very high rpm after being thrashed hard, it will get down to tickover without too much delay or hesitation. YES 3) When riding at 2mm throttle it feels right and doesn't cool down the CHT too much. STILL COOL (I think this is because of the 2mm carb drilling - too much for Pilot now?) 4) The mixture screw is at least 1.5 turns out. = 1½Tickover = 1200rpm by gauge; still seems high though. IDLE = 2Tripple-Whammy SEIZE set up:Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, and.... 45/160 - 42/160 – 40/130 (1½) 138 – 135 - 132BE3 – BE3+1 – BE3+2 AC160 – AC17004(Obstr) – 04 – ? You'll see the note I made then about the lean Pilot and the 2mm drilled carb, but that might have been my CHT starting to play up. Incidentally I'm after a Dellorto 8491 - slide cover for Si 24 & 26 (or a Spaco one) if anyone's got a dead carb lying on a shelf; it's this bit: www.dellorto.co.uk/shop/dellorto-motorcycle-carburettors-parts/carburettor-parts/si-parts/slide-cover-si-24-24/www.beedspeed.com/carburettor-slide-8491-si24si26-p-9724.html?osCsid=8b0ks1vbtvmkf8ishe75e775o5
(I'm waiting to see if Beedspeed have one in stock)...
For interest, other than the slide itself, this seems to be the only other part that isn't interchangeable between Si20 and Si24/26 carbs.
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Post by vespasco on Aug 4, 2016 19:51:44 GMT
I'm sure I have one, (probably 2 or 3 in fact), if you can wait a few days. Do you want non/autolube slide rod with it?
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Post by henri on Aug 5, 2016 7:15:50 GMT
if vespaco doesnt have 1 i might have , are you sure a 20/20 wont fit ,(reckon ya right but dont "know"), as ive def got a few of them . H
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Post by sime66 on Aug 5, 2016 7:41:04 GMT
I’ve got everything I need for it except the slide cover; I used a spare donor Spaco 20 carb for all the missing parts. I’m surprised that the slide cover width is the same; ok, very slightly wider (I expected that to be wider for the slide) – same screw centres though, so a 20 carb one physically fits (to test running of slide against spring), but the chamber is deeper on a 26 so the 20 cover doesn’t actually cover the top of the end of the 26 chamber – see photo (look at where the round spring-seat is on it compared to Beedspeed image above). Yes it all slides smoothly (I put my No5 in for now), I’ve checked all the threads, blown all the channels through and wiped its bottom (wet & dry on mirror to get it good and flat), I haven’t checked its valve seat, but I have spare tops; 20/24/26 are same size there. I think there’s a decent chance it will be a good’un, but won't be sure 'till I use it (and it didn’t really work out that cheap after I’d found all the bits for it):
I’ll drill it to 1.8mm and do the inlet/float mods too, I’ll probably do that today while I can’t do much else – a recap of that job here:
vespa.proboards.com/thread/5222/brief-build-update?page=11 (Dec 20th)
If you have a spare 24/26 cover, that would be great; I can contribute to the Monsoon Fund, or find something else you need; you mentioned you’re short on Pilots, and I might have some duplicates. Or anything else you can think of associated with your impending list of enginny jobs……………
What was and still is bothering me about my last good, safe set up is the 42/160, which is off the lean end of my table (below); I think maybe because the 2mm is too much for the Pilot – this is my hunch, and why I’m thinking about trying 1.8mm. But if it’s OK when I go back to it, I’ll leave well alone for Summer. Interesting to note pxguru has 50/160 on the ‘final’ summer set up on his. I know I keep posting this table, but that’s because I’m forever looking for it to refer to:
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Post by pxguru on Aug 5, 2016 10:43:24 GMT
As you do, I do think that the 2.0 mm is too much for our level of tune. I have managed to get mine running ok and yours will be similar if you continue with the 2.0 mm. If you are doing some experiments for us, it would be good to start with 1.7 mm. The original hole is 1.6 mm,so as little as is needed is probably the answer. 1.7 mm might be enough, as area of the hole is what we are interested in. I am going for another ride soon and if I am still happy with it it will stay like that for now. If you find that the smaller hole works even better, then I will buy another 26/26 as well I really do want it running on AC160 and BE3 but happy as it is for now. There are other ways of making the 2.0 mm drilled carb body leaner. The first idea that comes to mind is to lower the float level a few millimeters.
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Post by sime66 on Aug 5, 2016 12:38:23 GMT
I missed your post, H; we must have posted at the same time, but I think I’ve covered your query about the difference anyway, and I’ll be glad to have one off either of you. Pxguru; I’m glad you don’t think I’m on one of my dubious theories! I’ll also stick with 2mm for now if I can, but have a Plan B up my sleeve now. I’ve noted you suggest starting with 1.7mm, which I’ll do; when I’m more in the mood I’ll make a little study of it as I go. Enjoy your ride!
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Post by vespasco on Aug 5, 2016 16:47:13 GMT
I'll send you my si26 guruji. That'll be plenty lean enough! hahahaha
I'm thinking a lighter float wouldn't put so much pressure on the fuel going into the jet well. Maybe.
We can only assume this feed hole acts as another jet, or restrictor, for the actual main and idle jets. Otherwise it floods? That's why we need such a small idle (small number). I can't quite get my head around the fact that the jets should limit the fuel flow. Yet just by drilling out the feedhole it allows more fuel through the same sized jet!? I'm sure there's a logical answer I've over looked.
I'll dig out that cover too and send it monday or tuesday sime
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Post by sime66 on Aug 5, 2016 17:49:43 GMT
Now I’ve got to get my thinking brain in, Friday evening is probably not the best time for this. A lower float level makes sense to me to overcome the bigger hole size if jetting can’t sort it, but is that a lighter float? A lighter float will sit higher and close earlier, so yes I think you’re right vespasco. These holes then: * We know for sure that the size of the hole limits the flow rate into the jet well. * We know that we have problems with 1.6mm standard, which we’ve compensated for with bigger jets - around 160 and home-made bigger ones. * We know that increasing the well hole decreases the Main Jet. * We think we know that this also provides too much to the Idle jet well, resulting in the Pilot Jet needing to be too lean to compensate. (My thinking here is when the MJ isn’t working the level is the same as the float chamber, and the Pilot well will be the same too, which is too high or not dropping because flow into it is too fast, maybe – the rate of fill of the Pilot jet well). * I suspect guruji is also thinking the BE3+ or BE2 issue can be overcome by getting the hole size right, so we can get back to BE3 (similar reason; the 3+ or 2 is compensating for the big hole). * I suspect that the hole size won’t be the same for each of us, though we know it’s between 1.6 and 2mm. * I have the vortex too; I don’t know how that changes things (bigger MJ than without for me), but we should remember it when comparing results. * We’ve all got drilled 26 carbs now that we can probably still use, but which might be better with a smaller hole (yours behaving particularly oddly – even bigger hole and still lean - needs investigation, vespasco, but you’re on it; your big holes are certainly not making it lean). Beedspeed do have the 24/26 slide cover in stock at the moment; there is no hurry to actually send it, vespasco, but making sure you have one, or you H, would be handy, so I know whether or not I need to grab one from them while they’ve got them (Eurocarb don’t stock them now; Matt sent me an email earlier). I’ll dig my box of carb stuff out again over the weekend to make sure what I’ve said above goes for all the covers I have. I'll start small (1.7mm) as suggested; incidentally these are the sort of little drills I got before for the carb (1.1-2.0mm): www.ebay.co.uk/itm/Drillpro-10x-PCB-Print-Circuit-Board-Carbide-Micro-Drill-Bits-Tool-0-1mm-2-0-mm-/400950208588?var=&hash=item5d5a7ea84c:m:m_yWVenwLz-OZUShlDfn3zQ....and for the jets: www.ebay.co.uk/itm/20-PC-MICRO-HSS-TWIST-DRILL-BIT-SET-HANDY-STORAGE-CASE-0-3-1-6mm-SIZE-BITS-/360503085009?hash=item53efa887d1:g:kIUAAMXQMTlRbm8uEdit:
A couple of afterthoughts, having slept on it: * We’re comparing carb drilling size with MJ size, when we should be thinking about combined MJ and Pilot size. * I mentioned before, but forgot to mention last night, some of my selecting of leaner Pilot might have been when I was getting cool Progression CHT temps from a failing sensor/gauge, so I’m going to be trying to set up a richer Pilot first anyway. As you were, chaps; back to your Cornflakes…………………..
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Post by henri on Aug 6, 2016 7:31:03 GMT
if your ok to carry on as is thats good , didnt get a chance to dig out the corpse of my crackered cosa200 24/24 yesterday .am at the "outlaws" 50th wedding do today an away tommorrow til thurs .so wouldnt be able to post til friday earliest .let us know later in the week if ya still need it . am well jealous , am 1 needle n atomiser swap from perfection i hope on my polini 177/v50 , its going like a rocket but still slightly lean. will have to wait a week to find out now . have fun an some good rides . H
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Post by sime66 on Aug 6, 2016 8:44:28 GMT
I’m happy, H; this stuff we’re doing now is fine-tweakery and curiosity, (for mine, anyway), which can take as long as it takes – the 2mm drilled 26 is OK, I’m still riding while I’m doing these last bits, or rather I will be when I can get a boot on again! I’m still gonna play with the drill size in a 26, but there won’t be much downtime ‘cos fannying about ain’t what my scoot’s for. I’m also still slightly dubious about ignoring my temps; although logic, the plug, and you chaps tell me otherwise, I’d still like to get to the bottom of it, and would be happier playing with carbs if it was working properly. This morning I’ve just had an hour hobbling in the garden to make sure she’s ready for MOT, after MOT there’s a big list of Autumn jobs that I just ain’t in the mood for at the moment (disc fork swap, engine out for new mounts, and Kurust and waxoyl round her bum while engine’s out); there’s only really a narrow weather-slot between MOT and Winter to do Autumn Jobs – that caught me out last time I did the rust and paint on underside and front-end when late-Autumn was becoming unhelpful. (I’m thinking about renting a corner of KTM’s garage; maybe I’ll mention it after he’s done my MOT). I’ll do it all when I’m in the mood; it’s meant to be fun, not a chore working through a to-do list.
Have a good weekend; try to behave yourself!
BTW, whilst reading back over several of our posts, about a year ago you said you were getting a new phone and were going to give MicroDyno a go; lets have some data for this whizzer Polini 177/v50 then!
Re: 24/26 slide cover, if vespasco hasn’t got one, I’ll still be after one; Beedys have them at the moment, so it will be you or them – if you have a dead 24 it sounds like you will have one. We’ll sort it next week one way or another.
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Post by pxguru on Aug 7, 2016 8:19:38 GMT
Although I am happy enough with mine, it does feel it is not perfect. And when setting up a carb I do perefer perfect. It will run fine with the 2mm for now. Once your experiments are done (MOT and toe dependant) then I will either drill an old 24/24 and put that on, or buy another new 26/26, or find a way of reversing the 2mm on this 26/26 (ideas?).
This is another of so many ways to tell that Vespas are Italian designed. The jetway 1.6mm (2.0mm) in the carb body is, like Vespasco says, working like a pre jet and seems to be critical to the function of the emulsion tube. Although putting in a smaller main jet fixes the problem at WOT when the differential pressure is higher, it doesn't seem to restrict the flow enough at lower throttle and the emulsion level is not dropping to open air holes at the appropriate timing.
My thinking is that we should do as little drilling as necessary, aiming for main jets between 140 and 150 would be my guess.
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Post by sime66 on Aug 7, 2016 8:51:30 GMT
This morning I have good-humour fatigue (not really, but a quick moan to myself will do me good anyway). I got out in the garden and did normal pre-MOT checks with non-running engine yesterday morning – all good, tweaked, sorted (my foot felt fine too). So this morning I rode to the indoor carpark where it’s dry, quiet and dark to check all my lights, and my tail light is on constantly, and my brake light comes on when I turn my lights on. I know it’s just a matter of faffing around to find it; that shouldn’t be a problem, but after walking about on my foot yesterday, and riding this morning, it bleedin’ hurts again, and I need to be out tweaking and riding to sort the scoot for MOT. I came back in and had a look at my wiring diagram and did a list of things to check, and went out and did some quick engine-off ones, now I need to rest my foot so I can do some engine-running ones up the lane in the morning..... Buggeration! So for now I’m not too bovvered about where between 1.6 and 2mm is optimum for the carb; I just want to get my bit of paper for the year again. However, after a quick read of yours; * I also was thinking about how to fill and drill the hole (esp for vespasco’s 3mm); the big problem is keeping a clear channel, and not having any bits fall off and block jets later – more of an internal cover with hole, than a filled hole re-drilled I think. Your lower fuel/float level scheme might help, but will it then mess up WOT? * Whoah there! I don’t want you to be waiting for my experiments; that job is well down my list of priorities; I’ve got current foot malaise/MOT first, then Autumn to-do list, and if I get the 2mm carb going OK with previous safe good jetting, the drilling test might be ages off. My tests are not imminent. I should think Vespasco will have his flywheel and kickstart sorted and his 24 back on before I get to it. * Too much flow causing jet well levels not to drop quickly enough at lower revs is exactly what I’m thinking too, though my thinking has been more around the Pilot than the MJ well and emulsion, but I can see the same logic applying to both. (I see this, maybe, tying in with float level ponderings above too). Now this afternoon is dedicated to Rio Women's Road Race, foot up, and (just maybe) some staring at my wiring diagram to see if I can invent some dubious theories about my bleedin' tail and brake light…………
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Post by henri on Aug 7, 2016 10:59:03 GMT
closing a drilled carbs hole , 1st thought a right sized jet jammed down it ,old pilot jet end drilled to right size . 2nd thought , the solder on brass nipples for throttle cables stuffed in as a insert n drilled to size . H
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