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Post by sime66 on Nov 6, 2016 10:18:04 GMT
Hi chaps, this is more for conversation than advice; maybe a bit of picking brains at the end if I’ve missed something, but she’s mainly good, and I’m mainly working through this new issue as time permits, which isn’t much with short daylight hours and lots of jobs on.
During late Summer/Autumn I pressed on with this carb jetting/CHT temp issue, the conclusion of which was I could live with about 170⁰C CHT indicated, which I learned not to believe or worry about too much, and I still had decent plugs anyway (I’m getting a good plug at 170⁰C now, where I was getting a white plug at 160⁰C before). I felt there was still more to be had with leaner jetting, but always wary of temps and aware that colder weather was coming, so not too bothered about getting it too close, and happy just to have it OK and reliable over the Winter.
Most weekends I’ve had a tweak and a blast and I got it back to my previous best jetting before the tweak that caused the seize; I was back to:
Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, 42/160, 135MJ, BE3+2, AC160, #4 slide With a safe plug and about 170-75⁰C – not full-out long WOT (which I don’t do anyway round here), but the point where I didn’t want to push it up more (but I think it is hotter before that point actually).
But I couldn’t get the 42/160 to idle nicely, though I had before, I then noticed I couldn’t get the 45/160 back to a decent mix/idle setting either, so began to suspect something else going on. My thoughts were roughly:
1) Air leak – check torques at carb, head and exhaust stub. 2) Is exhaust past its best – 4 y.o. SR2; painted every year, but ask the chaps how to test it can I pump it up and put it in the bath like an inner tube?. 3) Are these old rings a problem; never was happy using those instead of new, and not sure my point about the ring-gap on the worn ones I put in after seize was ever noticed. 4) Clutch oil seal – it’s time for an oil change anyway; I’ll check it then. 5) Has timing slipped? (Stator loose, woodruff bent/sheared).
The other morning, for the first time in three years, it wouldn’t start in the morning. I bumped it and it started but wouldn’t run, and I pushed it home.
Next morning I stripped my carb top, blew all the jets and checked I had fuel, all of which seemed to be OK. I did resistance tests on stator, CDI and HT and put another plug in (keeping the old one for inspection). She started again, but still wouldn’t idle. – Lots of white smoke reinforced a suspected seal, but it was just carb cleaner, and I’m glad to say it runs smokeless now after a run.
Yesterday I decided to torque everything down, and when I got to the carb I noticed that the slide wasn’t returning fully and smoothly, so my idle-screw adjustments weren’t making any difference. I removed and stripped the carb, blew it all out – and the carb channels, cleaned the slide and grooves to make sure slide was running smoothly, and I gave it a quick flattening with wet & dry and made a new gasket – the carb box was still tight; I’d threadlocked the screw last time, so I left it alone. It’s now torqued down correctly with a new gasket and the slide moves freely. Although I had blown and checked the 42/160, I did put the 45/160 back in because I had record of settings with that Pilot that gave me good results (I've been gradually going leaner). I should mention I have a new RamAir filter, so I'm not restricting air in (though I have just made a note to check it's still clean).
This morning scooter started easily on choke, choke went in pretty quick and it ran nicely, although I had to keep the revs up at junctions, I went for a blast to get the engine warmed-up; good numbers considering the slight de-tune (0.2mm packer removal): 8640rpm (97kph/61mph in 3rd) and 140⁰C from a 3⁰C ambient, and then went and parked up the lane to try to set the mix/idle up properly. Still the same issue; I can only idle with the idle screw wound right in, and it bogs terribly when I blip the throttle – even stalls. Starts again with throttle wide open. To me that suggests rich (the mix screw is intact and the threads are good and I checked it was moving when I had carb off for cleaning-up, so working as it should), so although I’m going to torque-check the head anyway, I don’t think that’s the problem, or any air leak. I will go back to 42/160, and on to 40/130 but I’m not sure this is just Pilot selection or setting up now – even a rich jet wouldn’t make it so far out that I need the Idle screw wound right in to idle. I also need the idle revs pretty high (with idle screw right in) to keep the engine running, which makes me suspect the rings again; compression.
Next time I have time, I’m going to torque my head anyway, and I’ll repeat this morning’s test with 42/160 back in, then 40/130 if necessary, but I’m beginning to suspect it’s something else – still probably carb-related, and specifically Idle and Progression (Pilot/Mix/Idle), not MJ/AC etc because when throttle is open the scooter is nice. But maybe rings/compression; that one’s still niggling me too.
On a related subject, another observation and question. A slide on a 26mm carb has to travel further; I wonder if the slide spring on it is the same as for a 20/24mm carb. My slide spring seems a bit feeble for those last few mm of closing, and I see there’s different strengths available for PHBH carbs; I’d be happier if my carb snapped shut, so I’ll be taking some other carbs apart and comparing springs – wonder if anyone else has noticed it.
That same issue (carb not snapping shut – which I know is how some of you like it anyway [vespasco]) leads me on to changing my throttle cable. This is a job I had planned to do when I changed my forks/headset over to disc, but I might need to do sooner. Are there any tips/tricks to making that job as trouble-free as possible? I haven’t looked it up yet anywhere, but at present I think disconnecting it had headset and using the old one to pull the new one (or at least a wire) through and out backwards seems to be the sensible approach; any advice on that? Also, Is there a throttle return spring in headset? I will check myself later – just thinking aloud.
I’m not doing loads of work on it, or running back and forth and giving a running commentary on progress now the Beast build is done; this is now a back-burner job that I deal with when I have inspiration and time; as it is (until this most recent issue, which does seem more significant) it gets me where I need to be, with decent performance and safe temps, and I’m not looking to make work for myself, but I would like to get back to a sensible Pilot and sensible mix/idle screw settings and a decent Idle/Progression, tick-over and warm start – which has gone astray for some reason I haven’t yet found. If I don’t find an actual cause, I’ll just get the leanest Pilot that gives me decent mix/ilde settings and response – as long as my Progression plug and temps allow it. It isn’t my intention to swap 26mm carbs, or play with drill holes this side of Spring, unless I really have to; I just intend to get it safe and reliable again for the Winter….
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Post by pxguru on Nov 7, 2016 4:07:09 GMT
Was wondering how the Beast was doing. I think you just over cooked your plug when it wouldn't start. They still spark, just don't run! I doubt there is anything else wrong inside your engine at all. Stop worrying about those old rings, you will know when they need changing. Now the weather is colder its it should get leaner.
My tourer still has what sounds like the exact same issue. SI26/26 with 2mm drilling, similar inlet timing and similar port timing. Reading how yours is seems to be the same as mine was, I really improved mine with the BE2 and AC185 but its not quite enough and I won't be happy until it is. Also the BE2 could over lean the mid range on a long motorway run. I have another idea how to sort it and will be working some more on this issue in a few weeks time. I am hoping to end up running at least a 55/160 pilot after. It's always the set up of the first quarter throttle that's the hardest on any carb.
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Post by sime66 on Nov 7, 2016 8:48:54 GMT
Thanks for your reply; it’s good to have another perspective, and maybe keep me from following too many of my unhelpful hunches, though I have been trying to read and learn from what we've already done, as much as possible.
I had more time to think about it yesterday, and had a good read back through the big ‘Brief Build’ thread as well last night, because I know I keep going over some of the same things we’ve already covered; I haven’t learnt and remembered everything we’ve discussed or done. Those number and temps yesterday are the best I’ve had since the seize and de-tune, and predictably they also coincided with the change here from mild to cold. There’s a couple of interesting things from that: 1) You predicted about 500rpm down on previous (with 0.2mm gasket), and I’m getting about 300rpm** down, so that’s pretty good, and must suggest there’s not much wrong. I wasn’t even really blasting it; just warming the engine up, but I keep noticing I’m not using the full range of throttle these days, so as the CHT was sensible, I opened it right up and got to 8640rpm without trying or noticing; the tacho shows max revs when I switch the ignition off. I’m aware and very much noticed I’m into leaner running and will check my plug properly to make sure I’m still sensible, especially if I end up with a leaner Pilot for now. 2) With a 3⁰C ambient, my temps for local nippy running are sensible again. As I found before, the cool air cooling seems to be more significant than the same, leaner air burning; although I’m leaner, I am cooler – for local nippy riding, anyway. This will also give me a better chance to push it a bit more on the dual carriageway if I sort this other issue out and if the mood takes me. I’m noticing the leaner running, and benefiting from the colder air cooling as well. 3) Those Sunday numbers must also suggest that there’s not much else wrong from my list of possibilities. (I’m not obsessing about numbers; I wasn’t even looking at dials or gauges, I just noticed it felt and recorded a good performance without really trying. It’s also comparing cold November with warm June running**).
I agree that long-term the solution will be with getting a more sensible Pilot with the carb drilling changes we talked about, or as I remembered from reading back last night, your suggestion of reducing the float bowl level. Those are things I will tackle, maybe if it’s mild or dry over Christmas holidays, but not in snatched time on weekends at the moment really. It would be better for me to resolve this idling issue before introducing another variable too; it was OK before, if not perfect. It did remind me to get my other 26mm carb out and finish doing the inlet, valve and float bowl (1.7 then 1.8mm) mods, to have it ready to swap over though. If I get the second Si26 running nicely with smaller drilling, sensible Pilot and bigger MJ, I might get back to blocking and drilling the 2mm Si26; there’s more jobs than time at the moment, and I haven’t even started thinking about my planned Autumn/Winter jobs. I’m resisting the temptation to take my Si24 off the other engine; I don’t want that one to become a parts donor, or to complicate the options more – I’ll stick to fiddling with the Si26s.
I do still think what I have now is a bit more than just a difficult to set up first quarter though; if it was just not perfect I’d have lived with it over Winter; this is more like just useable, and certainly noticeably worse than before – and its onset coincided with the non-start the other day (which incidentally was when it was still mild). I’m going to mess with leaner Pilots again, but if I’m getting the same combination of screwed-right-in (open) Idle, just to tick-over a warm engine, regardless of Mix screw, then something else must be going on with that carb (or, less-likely, elsewhere); another reason to get this other carb ready. I have looked at the characteristics of a BE2 this morning; I can see it is leaner, low and mid, and I can see why that might be good (it is still my intention to get rid of the home-modified BE3s at some stage as well, but up to now it’s felt good with BE3+2). I’m sure I have all the atomisers in my box of jets, but my main issue at present is strictly at Idle, before the atomiser and air corrector are active I think. BE2 & AC185 sounds a bit scary to me too, after my BE3+2 and AC170 mishap.
Anyway, some tweaks in the week, and another test or two at end of week or weekend. First job; does any Pilot give me a decent Idle now? Several would have before……
No more mention of worn rings, either.
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Post by pxguru on Nov 8, 2016 4:02:24 GMT
Its unfortunate the weather has put it into the near un-ridable category. I have been giving this a lot of thought to try and fix my own scooter. I am really sure yours is exactly the same problem. The whole problem as I see it is that we have pushed the carb beyond what it can do. When yours is running safely, even though yours is still a touring tune, in my mind, if you ever put your 177 up against a bolt on Malossi 210, you would soon realise how much power it puts out.
Its our high rpm thats makes this set up on the SI style carb difficult. Our tuning on a needle type carb would end up with a lesser sized atomiser (like 2.62mm) and a pointy ended needle (like 1.6mm tip). This would hold the MJ way back for the first quarter throttle and let it rip at WOT. On a needle carb the point ends up thinner for a more aggressive state of tune. On the SI carb the atomiser works differently (more like in a four stoke carb actually). The slide needle diameter equates to a similar result, like when changing the AC in the SI carb. The needle taper adjustment on the SI is not so easy.
The whole issue for us is the main jet overlap. On a needle carb the amount of main jet is regulated by the slide needle. On an SI carb the main jet regulation is done by differential pressure (float bowl to venturi) and not directly slide position, only in as much as slide position affects the differential pressure. For us, our tuning (and 2mm drilling) is sucking hard right from the start, pulling a bit too much on the main jet, even on tickover. This is swamping the pilot jet. Reducing the float bowl level will help low down rpm but run way too weak at WOT. The 2mm drilling is adding to this problem but with any less at the higher rpm will run to weak at WOT (ideally we both need a bigger MJ as it is). We have a rock and a hard place situation. I think I have found a way out but want to do the experiments on mine first. And you are right it does involve some drilling. I won't be in the same place as my tourer for 2 more weeks yet.
You can do an experiment yourself to see what I am on about but be careful. If you reduce your main jet to something suicidal, like a 120MJ. You will see that your tickover and pilot work great again and you can get up to 55/160 (where I really think it should be). If you try to ride it, it will just seize again after 2 minutes. Will be way, way, too weak at anything over a few thousand rpm but tickover and progression will be lovely.
To get it running better for now. Re jet the whole carb from scratch with an AC185 (you will need one for later anyway).
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Post by sime66 on Nov 8, 2016 9:20:43 GMT
I can see you’ve been thinking about it, and that’s going to take me a few reads-over to understand and catch up, which I’d prefer to do before making changes. I do think we are seeing the same issue, but a couple of quick clarifications specific to mine to get those out of the way, but not really the main point of your post: 1) My tick-over issue started before the cold weather. Rough order of events; several Sundays back, I was still playing with Pilots and mix/idle and couldn’t get 42 or 45/160 to idle and thought it was odd (both have been ok before – agreed that was late Summer/Autumn), and eventually I gave up and rode home, thinking there was something else, and I’d have to check my carb over and generally check for blocks and leaks. The Monday morning after that was when it wouldn’t start (still mild both days, but the non-start was after I'd already thought something was wrong). This weekend just past I’ve checked it all over and found nothing wrong – and I also got a good, lively performance, in the cold weather, to reinforce that this is probably a low-rev jetting/adjustment issue; it’s very rideable if I keep the revs up. 2) I’m not sure I should have said near-unrideable; I’m trying to think how better to put it. Imagine if the engine was always cold and the choke was dodgy; I’m having to select neutral or have the clutch in and keep the revs up for junctions and slow riding or the revs just continue to drop off, but when I open it up it’s great. But it stays like that when warm, and to get it to idle I’m having to have the Idle screw wound right in (open slide – though it doesn’t race, just idles), and with the Mix screw not seeming to make much difference. – Like the Pilot well was permanently flooded, as you say, or like it’s rich at idle regardless of my Pilot. (I have cleaned and checked the choke isn’t sticking open).
Putting that aside now, I can see a couple of points you’re making specific to our mutual issue, but I need to give them more thought later: · We are pulling on the MJ stack at tickover, and swamping the Pilot as a result. I understand we’re swamping the Pilot because of the 2mm drilling, but is pulling on the MJ stack swamping the Pilot, or is it adding MJ mix at Idle? (MJ overlap at Idle?) · A bigger AC will help. I’m pretty sure I have AC185, if not I will get one. Won’t a bigger AC require a bigger MJ, and won’t that counteract the benefit the bigger AC gives at idle? · Less than a 2mm drilling is going to give problems at WOT. (Are we decided it’s not an option?) · Reducing float bowl level is also going to give problems at WOT. (Are we decided it’s not an option?) · You have a possible fix for the float bowl to venturi differential pressure at Idle pulling the MJ stack issue, it involves drilling – and that’s got me curious too. As it happens I was reading a bit about differential pressure above and below the slide in the Dellorto Bible last night; I’ll go back to that later.
I don’t like the sound of your 120MJ to prove the tickover experiment, so I’ll happily take your word for it, but I am interested (and quite surprised) that the MJ is affecting the Pilot at idle. That’s for our tune or carb mods; not normally?
I can handle the AC185 re-jetting; that sounds sensible now, though a better understanding of it on my part will come later with a bit more reading later (dropping the level in the MJ stack?). I’ll do that after I’ve had one last go with 42/160 and 40/130, just to prove the problem to myself now that it's pin-popinted to that, and maybe get Idle/Progression better for now, while I get my hands on AC185 and now I’m not distracted by my other hunches. You might do your experiments before that anyway.
We want our MJs bigger, and we want our Pilots richer (bigger - 50-55) too; the Pilot certainly is lean to compensate for this issue, which we’d previously put down to the 2mm drilling, but it was also the 2mm drilling which previously enabled us to get back to sensible MJ sizes. I guess that’s why we previously discussed the same solution, but 1.7-1.8mm; a happy balance – but not a workable one at WOT.
Excuse me if there’s anything dumb in my reply, I’m thinking it through at the same time as replying, and need to get on with other things, but I’ll have it ticking over in my mind today and have a better read later. I’m still reading yours and mine/understanding/revising as I go, but I have to post it and go out now.......
An evening edit: ….I’m too brain dead this evening to start reading more, but a quick update in case you’re on the early shift again. I’m buying into this being the same issue for both our engines now, and believing that there is nothing else wrong with mine. I’ve dug out my AC185 and BE2 from my spares, so will be ready to give your suggestion a try. I imagine I’ll be trying to get my 50 or 55/160 right at Idle and Progression with the AC185; do you think I should use BE2 or a 3 to start with? I imagine I’ll need a bigger MJ (though I note you’ve gone to MJ132 now), and start big (while I warm-up and set my Pilot); when I go over 140 I’m back into the BGM set for cosistency, do you think INC140MJ will do for safe starters?
I think you’re AC185, BE2, MJ132, 50 or 55/160?
….and I seized (In Summer; ambient 12⁰C) at AC170, BE3+2, MJ132, 40/130 (Remembering my inlet and filter are different, and my vortex needs an upjet).
So deciding on a start point for mine: AC160, AC170, AC185 BE3, BE3+1, BE3+2, BE2 ..? MJ132, MJ135, MJ138, MJ140, MJ142 ..? 42/160, 45/160, 48/160, 50/160, 55/160 (TBA; start 55 and see where Mix screw is?)
Then if I get a decent Idle and Progression, I can get the MJ down.......
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Post by pxguru on Nov 9, 2016 3:24:49 GMT
I continue thinking about this too. We do have the same issue but I think you have an extra one too. Your tickover is a little too much of a problem. Even with the excessive overlap, it should still cut out with the mixture screw wound right in. My first guess would be your choke is not shutting off fully. Make sure the plunger is fully back in and not stuck.
No time for a long explanation but we are thinking similar for now. AC185, BE2, MJ140 and pilot at least 48/160.
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Post by sime66 on Nov 9, 2016 6:31:00 GMT
I’ll know soon enough if it’s another issue as well; symptoms do sound like choke sticking open, but I have checked that on the desk and bolted back on and I can see it’s closed with my clear carb box lid as well. If problem persists I’ll have a closer look and maybe swap it over. Good we have same ideas about start point for jetting; I’ll see what progress the weekend allows. No need for more explanation anyway; it’ll give me time to catch up with your thinking so far and do some reading.
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Post by pxguru on Nov 10, 2016 3:46:06 GMT
You do make it sound like it is really not a stuck choke. It is something though. This is too much for the main jet to pilot overlap problem, however this issue will make your set up really sensitive to anything which was not perfect. Another possibility is something affecting the float bowl level, maybe your needle is passing a little. With the overlap issue it wouldn't take much for it to flood out at tickover.
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Post by sime66 on Nov 10, 2016 7:30:53 GMT
I’ll check it, and swap a needle, or a float bowl top if necessary; better to find the cause before moving on to the rejetting.
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Post by sime66 on Nov 14, 2016 9:12:15 GMT
I stripped and cleaned my float top, and put a brand new needle valve in; that’s without taking the carb off, but I think my Idle/Progression circuit must be blocked; I’ll take the carb off in the week and have another look at it. I didn’t even manage to ride it long enough to warm up yesterday morning; it was running horrible and cutting out at low revs, with choke in or out. Revs just dying unless I keep it really high – runs well at high revs, and just drops and dies as soon as I throttle-back. Not a lot of smoke or anything worrying as I did my U-turn in the lane and rode back over my tracks, but a strong smell of petrol when I got back. Must be a blocked carb, and I reckon it’s before MJ circuit overcomes the problem, and maybe last weekend I had the Idle screw fully in and so the slide was open enough for the MJ to give me enough to tick over without Pilot jet (I think I’m starting on the Choke jet, and running on the MJ with no Pilot jet); that’s my hunch anyway, will post when I’ve found something significant; carbs coming indoors for surgery………………..
Here’s a film of my sick scoot – looks like anything below 4000rpm it’s trying to die:
No worries; I’m not using it much at the moment anyway, so I’ll just fiddle when time permits.
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willow
2nd Class Ticket
Posts: 46
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Post by willow on Nov 14, 2016 19:32:32 GMT
Them roads could do with a good sweep and a bit of Tarmac won't go a miss either.keep fettling im sure you will sort it..
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Post by sime66 on Nov 14, 2016 19:48:50 GMT
That's the old main road to Bodmin, made redundant by the A30, it's handy to have, but the locals get a bit agitated if I use it too much for testing me scoot. This engine is a beauty (or was before I over-tweaked it to destruction in June); I think I just have a bit of aggro with my carb at the moment, not a biggy.
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Post by pxguru on Nov 15, 2016 16:10:28 GMT
It does sound not very well. like you say, could be the pilot full blocked. Seems to go fine once the revs are up.
If you are taking the carb off, it wouldn't be much more aggro to do a pressure test. Just to be sure. Did you strobe the timing already?
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Post by sime66 on Nov 15, 2016 21:06:06 GMT
It’s quite odd; I had the non-starting a couple of weeks ago, and that rough running on Sunday, but in the meantime I’ve had good high rev performance, and just a bit of trouble getting it to idle nicely – it doesn’t seem consistent how bad it is – or it’s getting worse; not sure. I didn’t expect that on Sunday; I was all set to try out the new jetting if my carb-top job had sorted my Idle.
I’m sure it isn’t the Pilot itself; maybe the well though, or channel to it, or from it to Idle or Progression channels. – I have a spare Si26 body. Some of these other possibilities now are going back to my first post. I’ll do as I planned with the carb anyway; a thorough strip and blast - yes I can pressure test again fairly easily while I’m there. I haven’t strobed it since the symptoms started, checking timing was on my list. If I can get it ticking over well enough I can strobe it fairly easily, or anyway I can inspect stator for slipping and the woodruff too. If I’m in there I can torque the four crank case studs too. I can change CDI and/or stator from spares to check if necessary. - I've got several CDIs, including brand new; and several stators, rewired and checked.
Given the decent high revs running; I’m still thinking it must be external to engine – fuel or electrical, and carb is still my prime suspect. Even if it does prove to be internal, I'll have it properly in the indoor pits and do the back-end rust treatment and painting I should have done in September; maybe rent a corner of K-T-M's garage over Christmas and get all the jobs done.
I’m not stressed about it; I’ll just think about the best order to do it and fiddle as spare time and enthusiasm for it permits.
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Post by sime66 on Nov 20, 2016 8:39:32 GMT
Oh happy days!
We’re back in business. Don’t worry too much about actual performance, or the low revs rumbles (I just had the reinstalled carb with screws at 2½, 2½ - no seting up at all, I just wanted it to start and run without cutting out for now); I’m about to go to the new jetting and tweaking, that will be next job anyway, after a decent run to be sure, but anyway she’s back and she’s lively again:
Ignore date and time; it was 07:30 this morning, 20th November.
It must have been blocked Idle/Progression circuit or that suspected dodgy plug. Main point is that it isn’t inside the engine, so engine doesn't have to come inside, in which case I can fiddle at my leisure. When I U-turn I’m riding back through clean air, on a cold morning with a cold engine; nothing to suspect anything bad going on.
This was: 42/160, 135MJ, BE3+2, AC160
Going to: 48/160(ish) MJ140, BE2, AC185
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Post by pxguru on Nov 20, 2016 8:49:24 GMT
It is nippy isn't it? At least that is nothing major. Might have been a bit of swarf hidden in there? On with the new jetting. Be sure to get the MJ about right first, then fiddle with the mixture and pilot.
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Post by vespasco on Nov 20, 2016 10:57:34 GMT
Its nice to catch up and hear some good news.... I see you are sorted now..but i suspected the idle circuit (exactly where in the circuit i couldn't say)!! and also wanted to say..re-torque the head! I have to re-torque the head on mine quite frequently.. Every few hundred miles or so... And then it would slowly begin to stay tight. I had similar problems yesterday and today, kinda..blocked idle, kept cutting out.. I don't even have a screwdriver so had to take it to a 'mechanics'... = 'a guy with some spanners, screwdrivers and hammers' You should have seen the state of the plug before i made them clean it!! Its probably the original one by the looks of it! I wish i took a photo. Anyway, all is good now.. with you guys and over here I hope to hear of some more ground breaking si carb tuning tips for when i get back on the Vespa.
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Post by sime66 on Nov 20, 2016 11:21:02 GMT
What have you got to play with there then? Yes; I still intend to give it a once-over before Winter really bites; hoping that'll be it - checked and reliable, for a few months, and a proper tweak again in the Spring. Keep us updated of adventures......................
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Post by sime66 on Feb 5, 2017 10:10:27 GMT
It’s been five weeks since I even took the cover off The Beast to kick her over, when I put her away she was running, but spluttering and I wasn’t able to get her to Idle, but I’d really lost interest, stopped for Christmas, then couldn’t be bothered with it. After sitting, neglected since December, she started third kick with choke and throttle wide open; she runs, but the spluttering is still present, and didn’t clear with a warm engine – although I didn’t go further than up and down the lane because it feels like a breakdown is imminent. The spluttering seems to be when the throttle is more than half-open, but she doesn’t idle either. The main purpose of the run, other than to assess the situation, was to warm the engine up to drop the oil for inspection. It’s settling in a jar now, but there is no fuel in it, so an engine split seems not to be necessary. It also did not leak any oil over the holiday; I’ll measure what I drained later, but I’d say there’s about 200ml of dark oil – it’s the first oil change since the build, so didn’t expect clear and golden. After the warm-up the plug was oily, which ties in with how it feels, which I would say is that it isn’t getting enough air through the main jet (too much fuel - rough running), or it isn’t getting a decent spark at the right time. My main focus of attention is either carb or ignition.
1) I’ve changed the jets to 48/160, MJ140, BE2, AC185 – but the previous jetting had been OK before, so if the problem is with the carb I do not believe it is with fine-jetting, but a blockage within the body, or maybe that the jets keep blocking for some other reason. If/when all other possibilities have been exhausted, I may try a new carb. 2) I have changed the plug for a brand-new one, and I have a brand-new CDI, lead and plug cap to try if I need to. I can recheck my stator readings and timing as well. 3) I do not believe I have an air leak; this is rich through lack of air (or poor combustion), not lean due to a leak. Having said that, I will retorque everything again when I next go back to it. I’m pretty confident I won’t have to split the engine (the engine oil is settling now for inspection later), but I may decide to inspect and overhaul the top-end; I have all the hardware to do that properly if needed. Pxguru; I’ll follow your how-to for barrel removal without disturbing the studs. 4) I still wonder if my exhaust might be knackered, but I’m not really sure of symptoms or how I might test it. 5) I meant to check the tank to see if I’d lost any fuel, but I forgot; I’ll do that later.
I gave her a quick wash (because I wanted to clean the engine to see if I could find a leak), and she's sitting out the front in case the sun comes out. At the moment my battery is charging; I may have knackered it because I just left it to completely drain over this holiday, and my oil is settling for inspection. When those are done I’ll decide my next steps, and just work through the possibilities in a sensible order. This is just an update; I don’t want to create a lot of interest in this thread because I’m only half-heartedly getting back into it after a bit of a sad end to it last year, and a period of neglect. This is just to recap after an extended break from it; I probably won’t do much before next weekend, and that’s only if it’s dry enough for messing about in the garden.
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Post by pxguru on Feb 6, 2017 12:26:17 GMT
Hopefully not anything serious. Most issues would make it run weak so encouraging that its nothing serious. Could be the exhaust. Air filter might be no good. It could be the CDI. Your jetting might just not get on with Winter. If you reduce the main jet until the plug is not balck and the spluttering improves, we can see where you are. Don't ride it hard for more than a few seconds at a time and you will get away with it. From what you have said I doubt it will be much but annoying all the same.
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Post by sime66 on Feb 8, 2017 10:44:33 GMT
I had 220ml of very dark oil with little sediment and no fuel, which is good. I think I’ve pretty much convinced myself that this is just a run of the mill issue, not related to the build or seize, or just jetting either; it’s still the same engine that gave me excellent results last Summer, so it’s just a question of working through the possibilities; I’m going to start with all aspects of ignition first (because it’s simplest to discount with a fair degree of certainty): I’ll update when I’ve made progress. I can’t ride hard enough to need to worry about jetting too much at the moment anyway, but whether I return to my previous best jetting or persist with the new jetting arising from your findings, is a question for after this main issue is resolved. I’ve had a decent break, and there should still be plenty of time to sort it before the first signs of Spring, so no worries really.
Ignition update: I’ve Swapped all the HT over from CDI to plug – all new; readings were mainly as expected, so I don’t expect any result from that, but two points to note for myself to keep an eye on: · the HT into the CDI was a bit loose; I recall trying to screw it back in in-situ before and not being very satisfied with it, so maybe there was an intermittent failure there when engine was vibrating, though it measures correctly for continuity and resistance now it’s removed and on my desk. · I had measured the LT coil (Green – White) resistance as 540Ω after the seize in June, but I got 498Ω this morning. This is probably lower due to much colder temperature of metal now, but worth making a note to keep an eye on if I need to return to this if I don’t find something else….
I’ve got fresh oil in my engine, and I’m ready for another spin on the weekend; If I still have a problem (which I think I will), I’ve thought about the best order to check stuff: 1) I’ll check my fuel (tap, line, banjo and needle valve) and air (filter – which was new in Autumn, but may be clogged again), and have the carb off for another good strip and blast-through. I meant to check my tank level, but forgot again; it does all smell a bit of petrol when I take the cover off - this is becoming main suspect. 2) Then I’ll return to physical check of stator and timing. (I have a hunch it’s revving OK on the stand though, so I’m going to check that when I’m out on the weekend). 3) If that lot gives no result, I’ll do the barrel (inspection, maybe rings, and retorque) and exhaust (test for leaks) at the same time after that (because I have to remove the exhaust to remove the barrel with engine in-situ). I’m not sure what I’ll do after that, so hope to find something in next few weekends.
Can I safely pump up the exhaust a bit to look for leaks? Is that the best way to check it? If it’s OK I’ll paint it again before I replace it as well.
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Post by pxguru on Feb 8, 2017 17:58:59 GMT
The not ticking over is the biggest concern. Good to rule things out. To complete the electics you should strobe the timing, to make sure the flywheel hasn't sheared the woodruff key.
If there is something wrong with the exhaust it will run fully normal until about 4 to 5000 revs then start losing power but not splutter so much. Any exhaust leaking has little to do with this problem.
Set the carb up from the beginning as you said. Tickover and starting up, then progression, finally mid and WOT. Now we know you will never get it right on an AC160, keep the AC185 and BE2 in there and jet around that.
Do you still have the foam air filter on?
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Post by sime66 on Feb 8, 2017 21:43:03 GMT
Strobing, and stator inspection (including woodruff, timing mark on baseplate, wiring etc.) is on my to-do list at 2) above. Having a tickover will make strobing easier to do though, which is why I put it lower on list after another check of the carb. As mentioned above, I think it’s revving OK on the stand, which I think would suggest timing is OK, but I’m going to be more specific about under what conditions and where in the revs it happens. I did do a film on Sunday, but the wind-noise made most of the sound pretty useless, and low light made the gauges hard to read as well; maybe I’ll post it anyway – I’ll have another look at it in a minute; it’ll take a couple of hours to upload anyway. I’ll worry less about the exhaust until later; interesting where you put the revs problem with that, compared to the film though. OK I’ll stick to the AC185, but I’m not sure we know the AC160 would never have been right (it pretty much was right in June before the tweak that caused the seize). Anyway, I’m sure jetting is secondary to finding the source of the problem; I do not believe jetting is the problem itself – even a roughly set up carb would not be this bad to ride, or would be easily remedied with a quick tweak. This carb was never this bad with this jetting; it was very good with all I still have now – something else is going on. I think concentrating on the jetting has delayed me going back to these basic checks, so I’m inclined to leave fine-tweaking it for now (other than Pilot/Mix/Idle). Yes, I mentioned that I put a brand new RamAir filter on in early Autumn; it might be clogged again – I will check it when I strip the carb, and I’ll try running without a filter too.
OK, I uploaded the film in case you see/hear anything I haven’t yet. I did have a bit of a better look at what revs I’m getting, and it is only 3-4,000 before it starts to splutter, but it isn’t happy at any revs. (For the record; this is before jet change, so 42/160, 135MJ, BE3+2, AC160, I’ll do more on the list, and film, and see what I can discover over the weekend – weather and rugby permitting):
- Not exactly flying round the lanes like it was last Summer, or even compared to Nov 20 film above. (but don’t yet know why……) -
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Post by pxguru on Feb 9, 2017 11:29:04 GMT
It does sound rough. It just sounds like carburation to me. Still goes reasonably well and not mis-firing. I think it will just turn out to be jetting. With the atomiser/emulsion tube arrangement it does change in Winter. Seems a bit much but it wasn't quite right in the Summer either.
You have not mentioned but I assume the compression is still good. Kickstart feels about the same as ever?
There could also be some change in your float height with Winter. This can make it seriously rich.
Once the timing is confirmed and the plug is new, have a quick go at re jetting from scratch. Keep the No.4 slide, vortex, sponge filter, AC185 and BE2 all the same and just change the pilot and MJ.
First reduce the MJ until the mid throttle splutter goes away (don't get too hung up on the numbers, mine is about 22bhp on a 128MJ). Then, if the tickover comes back with a smaller pilot (aim for 2 full turns out on the screw for small enough pilot jet) then at least there is nothing mechanically wrong.
My tourer has a Winter cough too. As the revs pick up on progression. I will need a smaller pilot too probably 45/160 (45/140 if thats the only one I have).
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Post by sime66 on Feb 10, 2017 13:43:31 GMT
Definite progress here (I’m a tit, but at least me scoots on the mend): I only had a short time to have a quick blast with new HT changeover, and jetting, so anything I didn’t tackle is just down to time; some things I won’t need to do now, and others I just didn’t have time, but I can have another bash in the morning. She started about third kick, revved up nicely on the stand, pulled away lively, and she felt good, so I thought I’d start by trying to see exactly where the revs packed-up. At about 5,500revs (which is already higher than she went on Sunday, but I only got half way up the lane), the revs dropped right-off, and I couldn’t even get any slow low-rev progress, I thought my throttle cable had snapped; ironically she just dropped off and idled, regardless of what I did with throttle, but eventually she died while I was thinking. I noticed I was leaving a trail of petrol or oil behind me, and thoughts went to recent oil change, or the smell of petrol I’ve been having, but on closer inspection it was obviously petrol flowing down the back of the engine. I took the carb cover off and it was flowing out the top of the fuel filter cover on the carb. I tightened that down and checked the banjo, then turned fuel back on and waited to see if fuel was still flowing out at all, and all seemed good, so I put my panel back on, and she flew along nicely again. I’m not sure this is the only problem because I had the carb apart several times at the end of last year to try to find the cause, so it looks like perhaps I was a bit slap-dash with it the last time, so maybe not the cause, but it’s certainly been an immediate problem. I reckon I would have noticed something so obvious, but it is only when the tap is on, and it was cold and foggy when I put it away in December and gave myself a holiday, so maybe that’s the leak I saw, but couldn’t be bothered investigating, then. - (And I cleaned the engine on Sunday, so I could have a better idea where the leak was coming from, if it was still there). Once that was sorted, she got hot very quickly with the AC185/BE2, (166°C – if I can trust the CHT, which is doubtful), and I doubt the plug will tell me anything after such a short run. There’s no point us just keep on disagreeing the jetting point, and I have taken on board your opinion, which I appreciate and respect, but I really don’t think the previous jetting was the main problem (reading-back last night; it was exactly a year ago mid-February, that I had my first really good MD runs with The Beast, and I was still getting good runs mid-June; in my mind this problem is still post-seize, not a Summer/Winter issue – I gradually tweaked and improved my jetting between Feb and June last year – the seat restriction, the Ramair, the vortex, drilling the carb, trying leaner ACs, drilling the BE3…..): Feb 4th 2016:(Best with old seat and conventional filter) 48/160 & MJ132 (BE3, AC160) – 10°C ambient: 16.51PS @7681rpm, 15.89Nm @6617rpm, max 8639rpm = 97kph = 61mph in 3rd (= M.D).vespa.proboards.com/thread/5222/brief-build-update?page=16Mar 12th 2016:Polini vortex, RamAir filter, 48/160, 138MJ, BE3+2, AC170 – 5°C ambient: 16.83PS @ 7760rpm, 16.28Nm @ 5631rpm, 8927RPM max = 101kph = 63.2mph in 3rd (=M.D.) – Too hot – there’s also film of 116kph GPS = 72mph.vespa.proboards.com/thread/5222/brief-build-update?page=18Jun 16th 2016:(Best with new seat, RamAir filter and vortex - and what I was using before this AC185/BE2 change; but, agreed 10°C warmer then) Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, 42/160, MJ135, BE3+2, AC160 – 13°C ambient: 8750rpm (99kph/62.0mph) in 3rd, and 7410rpm (112.5kph/70.4mph) in 4thvespa.proboards.com/thread/5222/brief-build-update?page=22Jun 18th 2016:Si 26/26 (drilled to 2mm), Polini vortex, RamAir filter, 40/130, MJ132, BE3+2, AC170 – 12°C ambient: SEIZEvespa.proboards.com/thread/5222/brief-build-update?page=22But I will leave the AC185-BE2 in for now, while I set up my Idle and Progression, but depending on ambient temps and whether I encounter any more problems before I get to it, I may have another look at them when I do MJ (looking at film the high temp was after leak was fixed, so just from a quick blast in the lane at ambient 3°C I’m getting 166°C with AC185-BE2). She’s much closer to idling though, but that and the Pilot are my next jobs. I think I don’t need to strobe, but in any case I’ll do that when I’ve got a decent tick-over. In the morning I’m going to take the carb float chamber off, check the channels, threads, gaskets, filter and valve seat and needle, and on Sunday (hopefully) I’ll have a Pilot jetting session. I’ve been thinking and saying I think the problem is the carb, but not the jetting. It has perked up after a blast-through before, so I’m not 100% sure this is problem solved, but I’m definitely concentrating on the carb for now. I left my camera running while I was doing the carb top, so below are before and after films: Feeling good straight away, but soon dying due to fuel leak: This immediate problem found and fixed, and looking promising, but too hot with AC185, BE2:
Anyway, plenty of time to sort it before bunny-chasing season – I’ll have much more time to play when we have light mornings in a few weeks too………………….
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Post by mijapxman on Feb 10, 2017 16:25:26 GMT
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Post by pxguru on Feb 11, 2017 11:27:45 GMT
Good progress. A fuel leak explains it better than jetting. Back on track for the fiddling. It sounds like it is too rich at low revs and the temperature says it is to weak at higher revs. It may turn out that you don't need the AC185 and BE2 and could fall back to the AC170 and BE3+2 but for sure the AC160 and BE3+2 wasn't correct although the best yet. Stick with the AC185 for a while until you are sure it is too weak. To prove this one way or the other, first up the MJ until there is a clear Mid throttle splutter, When you get a good half throttle splutter reduce the MJ by two jet sizes (ie. 143 down to 138). After that reduce the pilot jet small number until you get two turns on the mixture screw where the revs pick up. Confirm it is all ticking over and reving up nicely. If when you get to this point and still see temps over 150C then the AC185 is too big for it.
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Post by sime66 on Feb 12, 2017 8:55:31 GMT
The leak was the obvious cause of the running problems, whether it had anything to do with the idling issue (which existed before I started playing with carb and before the cold weather), remains to be seen. With AC185/BE2 I will certainly need a bigger MJ to get some fast-lane riding and colour in my plug before returning to see if I can sort my Pilot/Idle out (or see if I still have a problem there); I'll progress with exactly method as you suggest above. My Spring-antenna seems to have gone off prematurely here, and it's gone very cold with freezing winds and sleet/snow showers again, so I'm staying in the warm for now. I think I'll get a more realistic MJ (and decide on AC/BE) when ambient is a bit more sensible anyway. (Should've kept the muffs on - brrr).
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Post by sime66 on Feb 18, 2017 16:29:58 GMT
Here’s a bit of an update, just while I’m thinking it all through, and planning my next steps, before a ride tomorrow. Keeping AC185 and BE2, I went to 45/160 to lean the low revs a bit, and to MJ145 to make sure I wasn’t getting too hot for a run round the lanes; getting to a known rich point before dropping the MJ to somewhere close. BUT. She wouldn’t start, or bump on Friday, so I kicked her and called her a b*st*rd, and eventually got her going (fuel off, throttle wide open) and she flew up and down the lane for a bit. I had thought she should run spluttery with such a big MJ, and she didn’t quite idle, cut out and then wouldn’t start again either, so, with the running well with a big MJ, I decided I must have an air leak. Anyway, I didn’t get a decent ride in. This morning I checked torque on head, which was spot-on, then I took head off to have a look down barrel, and all looks fine; no signs of blowing or leaks. Only, maybe a bit too much unburnt fuel, but that might just be because of the recent silly little runs up the lane without any decent long runs – worth noting anyway; that dark-brown tacky surface film would normally be carbonised black deposits:
(bloomin’ studs came out of the casings again – don’t think this is a problem though; they torqued down again nicely)
I torqued the head back down, completely satisfied that it wasn’t the cause, and has all gone back carefully, so isn’t a problem now – loctite 603 on those two studs. I think, given this head, no leaks etc., I can’t trust that CHT any more; this hasn’t been running hot like CHT suggests. I’d already suspected this because my plugs don’t back up the CHT. This plug now was new and showed no colour yet; that’s why I wanted to get out for a proper ride.
I then took the flywheel off, which was nice and tight on the taper; the woodruff key is in perfect shape, as is the keyway, and the stator is still exactly on the mark I’d punched between stator and casings, so neither stator or flywheel have slipped; the timing hasn’t changed, and remains at 19°.
I then checked the torque on the carb, which was fine. I then removed the carb anyway to strip it, blow it through, replace all the gaskets, and check the float and needle valve. I left the fuel on whilst I had the carb indoors, to check the tap was holding, which it is. The carb itself was completely stripped, blown-through, and every part inspected, cleaned and reassembled with new gaskets; I can find nothing wrong at all with the carb. I checked the carb box on the engine, which is solid – I’d previously threadlocked the fillet screw in place and it hasn’t shifted. I cleaned the gasket surfaces and I torqued the carb back down evenly to correct torque and checked the slide was moving freely afterwards, and I checked the throttle and choke levers, cables and mechanisms within the carb once it was all back together.
I can’t find anything wrong with any part of the scooter, so all that’s left for me now is to have a ride in the morning and see if I’ve inadvertently fixed something without noticing what – I’ve previously done all electrics from stator to plug cap as well.
If not, I’ll think about exhaust, and crank case pressure test (which I didn’t do because my oil was good when I changed it a few weeks ago, and there are no leaks, but will do a test if/when I take the exhaust off).
Then I’m stumped; she runs lovely – quick and lively, but starting and idling are not right for some reason; I’ll find it.
I’ll make a pre-emptive comment about jetting, so we don’t keep repeating the topic; if this was just jetting, I’d be able to tweak it to give me a cold/warm start and a tickover – although I can’t yet find it, and I’m running out of ideas, I do still think this is something other than just jetting. Also if it was just jetting, I see no reason why a previous good combination of jets (like those above) would give me problems now when they weren’t giving me problems before.
I’ll have a ride in the morning and update if there’s anything interesting to report. If she’s starting and running OK I’ll have a jetting session to see if I can get my Pilot/Idle sorted - more sensible ambient temps this weekend too; nice to be in a dry garden in my shorts working on scooter this morning. But I’m not spending another Spring and Summer faffing about with this though; I’d rather plod around on Old Faithful than have The Beast permanently in the pits or tweaking.
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Post by pxguru on Feb 19, 2017 14:29:02 GMT
This is sounding like it's gone weird. The poor starting, bad idle, high temps, white plug and there being no other issue all say that the crankcase pressure is going to be dissapointing.
The exhaust being bad will only affect the high rpm, where it seems you have no issue.
Edit; I see two studs came out when you didn't want them to. I would put them back in with loads of threadlock, so they stay in forever.
The biggest clue is the poor idle. I had one last year that had blown the crankcase gasket at the thin part round the primary drive. Oil seals were fine and just leaking through the gasket. Changed the seals and everything anyway.
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