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Post by 190mech on Aug 21, 2022 17:55:54 GMT -5
Looks good Brent!That level is well away from the carb throat,just gotta hope the bowl will not run dry during WFO runs..I'm sure you will test that!!
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Post by 90GTVert on Aug 23, 2022 15:12:48 GMT -5
This thing is turning into the Lectron. I try to be methodical and collect data and still I can't tune any new carb setup lately.
With the float height at 23mm as shown before, I tried it with a 165 MJ. It was running out of fuel bad. Not even needing to be WOT. It's odd. Acting way rich and then dying down suddenly.
Switched to 21mm float height setting. Now it will keep going, but it's way rich still. Breaks up bad taking off and then if I hold it WOT it breaks up till I let out.
I put in a 155, then 145 and finally 135 MJ. It got better each time. By the time I got to the 145, it spun the tire starting to move in the driveway. Since basically the clear float bowl time, it's been stuttering rich and I'm trying to get it to clear out, so I was surprised at the instant snap. By 135 it's pulling the wheel up easily and being nasty again.
The problem is, it's still breaking up to some degree at WOT. I stopped to do a test run with the 135 and it goes well instead of breaking up taking off, but the longer it's WOT the more it starts to stutter. I let off when I saw over 1300F EGT in less than 1/8 mile. So it's acting rich to me, but the EGT shows lean. Hmmm.
I thought maybe the float height was too low still. Maybe what I'm perceiving as rich when holding it is actually it starting to get low on fuel? Raised the float height to about 20mm. Just shy of parallel setting. It acts about the same AFAICT.
Now I'm not sure if I am missing the settings on the carb still or if something else is up. I did change out the plug again around the 155 MJ or 145... it's written down but not in front of me. Anyway, mild improvement over what it was doing, but not much change.
Usually a fouled plug is kinda the opposite of this. For me, it's most commonly tough to get going with a badly fouled plug, but once you get it moving and get RPM up it will get hotter and then clear out. This goes and then the longer I hold it the worse it gets and it's really only WOT that I get any kind of breaking up. With larger jets it will start breaking up at lower throttle positions or even when I quickly open the throttle in some cases. At this point it's not the wild stumble and stutter that it was with big jets, but it's still there. I don't see going to 130 or 125 as sensible after the high EGT.
I may check spark strength just out of curiosity later. It runs hard enough that being low on compression doesn't seem that likely to me. I mean it was full on blubbering WOT, just running awful, doing 62MPH at one point with larger jets. Last trip into town I was getting the wheel up at 25MPH or so. Doesn't feel that weak to me.
I may try to get a couple of quick clips up later. Gotta work on some other stuff now.
Oh. I when I stopped to do one test run a young deer crossed the road into a corn field. Now I'm riding down this road that I do most tests on with corn or trees on both sides in many spots like oh no not again.
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Post by Lucass2T on Aug 23, 2022 16:21:54 GMT -5
Could it be something else than the mj or float you should look at? Haven't read everything but this might be the atomiser being off.
A very knowledgeable guy told me the holes in them are being fed by air rushing in the carb from the intake trumpet. This air sort of 'slows down' the mixture coming up from the bowl into the venturi. Maybe you can try fiddling around there a bit.
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pewpew
Scoot Enthusiast
Posts: 254
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Post by pewpew on Aug 23, 2022 17:51:01 GMT -5
This thing is turning into the Lectron. I try to be methodical and collect data and still I can't tune any new carb setup lately. With the float height at 23mm as shown before, I tried it with a 165 MJ. It was running out of fuel bad. Not even needing to be WOT. It's odd. Acting way rich and then dying down suddenly. Switched to 21mm float height setting. Now it will keep going, but it's way rich still. Breaks up bad taking off and then if I hold it WOT it breaks up till I let out. I put in a 155, then 145 and finally 135 MJ. It got better each time. By the time I got to the 145, it spun the tire starting to move in the driveway. Since basically the clear float bowl time, it's been stuttering rich and I'm trying to get it to clear out, so I was surprised at the instant snap. By 135 it's pulling the wheel up easily and being nasty again. The problem is, it's still breaking up to some degree at WOT. I stopped to do a test run with the 135 and it goes well instead of breaking up taking off, but the longer it's WOT the more it starts to stutter. I let off when I saw over 1300F EGT in less than 1/8 mile. So it's acting rich to me, but the EGT shows lean. Hmmm. I thought maybe the float height was too low still. Maybe what I'm perceiving as rich when holding it is actually it starting to get low on fuel? Raised the float height to about 20mm. Just shy of parallel setting. It acts about the same AFAICT. Now I'm not sure if I am missing the settings on the carb still or if something else is up. I did change out the plug again around the 155 MJ or 145... it's written down but not in front of me. Anyway, mild improvement over what it was doing, but not much change. Usually a fouled plug is kinda the opposite of this. For me, it's most commonly tough to get going with a badly fouled plug, but once you get it moving and get RPM up it will get hotter and then clear out. This goes and then the longer I hold it the worse it gets and it's really only WOT that I get any kind of breaking up. With larger jets it will start breaking up at lower throttle positions or even when I quickly open the throttle in some cases. At this point it's not the wild stumble and stutter that it was with big jets, but it's still there. I don't see going to 130 or 125 as sensible after the high EGT. I may check spark strength just out of curiosity later. It runs hard enough that being low on compression doesn't seem that likely to me. I mean it was full on blubbering WOT, just running awful, doing 62MPH at one point with larger jets. Last trip into town I was getting the wheel up at 25MPH or so. Doesn't feel that weak to me. I may try to get a couple of quick clips up later. Gotta work on some other stuff now. Oh. I when I stopped to do one test run a young deer crossed the road into a corn field. Now I'm riding down this road that I do most tests on with corn or trees on both sides in many spots like oh no not again. Just get a 28mm keihin and problem solved
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Post by 90GTVert on Aug 23, 2022 18:54:11 GMT -5
Here is a vid with clips from each tuning run today. Watch the text in the corner to see what's changing. If you've watched the car show vids, it's a pretty drastic change from how well it did with low fuel flow and barely touching the carb. It all seemed to change around with adding fuel flow and the floats getting heavier. You can even go back to page 371 of this thread and watch when I first put the clear bowl on (hadn't changed fuel hose setup yet) and watch it run cleaner with a 170 MJ that I knew was too large but I was trying to see if fuel drained.
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Post by fly on Aug 25, 2022 3:30:46 GMT -5
I don't know know germane this is to a VHST, but when I was ordering some jets from Slavens I noticed something made for the PWK that's meant to prevent starving. I ordered it to examine with your issues in mind. It's just a modified float bowl cap design. slavensracing.com/shop/f2-racing-fast-cap-float-bowl-cap-ktm-honda-suzuki-kawasaki-yamaha-husaberg-husqvarna/It's a little bit shorter, has no inlet holes, and the bottom (inside bottom) is rounded instead of flat. I'll take some pics and post em up. Incidentally, they sent me those "AB" stamped jets for the MJs instead of Keihins. JD Jetting has apparently been sending those out, too. Waiting to hear back about that, unexpected from Slavens. Seems to be they're tested/verified third party jets.
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Post by fly on Aug 25, 2022 5:06:12 GMT -5
so the aftermarket cap is ~2mm shallower, owing primarily to the difference in a thread length. it seems to be the differences is the threads are flush with the interior of the float bowl, and the spherical bottom of the cap concentrates volume in the center. I'm not sure how this person came to this solution. I'm not sure any of it applies to your VHST. but every idea and little bit of data helps! ETA: also it's billet and orange anodized, so +1hp
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Post by 90GTVert on Aug 25, 2022 7:05:19 GMT -5
I don't think the modified drain plug applies too much for the VHST since the drain plug holds the main jet. I'm sure there could be some change to improve the amount of available fuel for it, but I've never seen anything else. Thanks for posting that though.
I checked spark strength last night with an adjustable tester. I was just trying to look at the camera and make sure the big spider that's decided to hang out by the scooter lately wasn't sneaking up on me while the lights were dim. Without checking video yet, I know it at least jumped a 1/2" gap so I'd think it should be strong enough.
I thought about ignition timing, but I really don't think that would be it. To me it all still points to air/fuel issues and the big change came with a change in fuel flow. Not really sure where to go right now. I think I'm gonna pull the carb off today and clean it and the filter. I don't think that's the issue either, but at least maybe I can check another possible cause off.
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Post by 90GTVert on Aug 25, 2022 13:42:33 GMT -5
Carb and filter have been cleaned. I've read multiple times that 50/50 Pine Sol original and water is great for ultrasonic cleaning carbs. Tried that. The carb is grey now. Steel bits look like they're starting to corrode. Brass came out awesome. Other people say they drop whole carbs in there and don't disassemble, so my initial thought that maybe different metals aren't liking each other wouldn't make much sense there.
I put a 145 MJ in it, because the 1300+ EGT in under 1/8 mile with a 135 sounds pretty hot to me. Pretty much as expected, it's the same. It acts just like what I'd expect from too large of a main jet. 1/2 throttle up is sputtering. Worst full WOT.
I got behind someone with a Harley sticker on their rear window so naturally they were going 30-35MPH in a 45. After putting around behind them for a minute, it went pretty well at first when I got into the throttle. That made me think about fuel level again. Maybe it could still be low and what I think is really rich is it running a little low on fuel. I tried being easy on it more and then getting into it, but I think that was just a fluke. I dunno. I'm going around in circles at this point.
I looked in at the reeds as well. With such a direct path, you can see them when the carb is off. From there, they look OK.
On a possibly brighter note; I hooked the Battery Tender up this morning. It sat on there for at least 5 hours before I rode it and it was still a solid red light. I left with battery voltage around 12.6-12.7 and came back with it the same. Maybe my charging system would be OK if my battery were alright. Could it be another one of those lucky coincidences where I found the regulator that charged 14.7-14.9V for me and then the battery gave up after the first ride? Is something else going on? Just like the carb, I'm still lost. I'll leave it on the charger and if it keeps wanting to maintain the higher voltages, maybe it is the batt. Obviously it's not in great shape so I should probably replace it anyway, but I just spent nearly $100 this morning on 4 spark plugs and a 2L of air filter cleaning solution. 2-stroke problems.
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Post by Lucass2T on Aug 25, 2022 16:59:21 GMT -5
Testing a different carb would be a nice way to see if the Dellorto is throwing a stick in your wheels.
Oldschool Mikuni VM28 or a Keihin PE28 roundslide MX carbs should be plentyful, not too expensive and are top notch quality.
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Post by 190mech on Aug 25, 2022 17:33:26 GMT -5
I was gonna suggest looking at the reeds! We have had some mixed results with Battery Tenders at the airport,a few went into overheat mode while sitting on classic airplanes,luckily it was removed before it went up in smoke... Have a near new nice knockoff PWK that ran well on one of my scoots I can send ya if you want to try it..
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Post by 90GTVert on Aug 25, 2022 18:06:47 GMT -5
Ryan offered his carb for a sanity check earlier today. (Thanks for the offers guys!) I don't even think I'd need a good replacement. If my 25mm would fit in the intake, it would prob at least be enough to tell me if something is up with the carb or there's an issue elsewhere. I've got a 28mm Dell PHBH (IIRC) here too. Not sure how well it fits either. Dare I say it... I even have the 30mm Lectron... but that may make me more crazy than I already am.
I have been searching to see what others put in their RC-One setups. With all of the RC-Ones out there using the carb that came with it, there must be an abundance of info... right? Wrong. Or at least I can't find it. I found that someone asked Jack Cecil what jetting he used. He said it came with a 150 (as did mine) and he swapped up to a 165 for break-in. That was in the comments of his dyno vid where it makes 30HP. Reading that critically, he didn't say it used a 165 for the dyno (but it may have). You know how these competitive folks can be about giving out any info. Regardless, much larger was working to some degree for him and I was at 160 before the clear bowl and finding more fuel flow.
I found some other 28mm VHST jetting info from Vespa tuners and Aprilia RS 125s and others. That's all over the board though. I've seen anywhere from upper 120s to 185 or larger. So many possibilities for different setups.
I've considered going back to the fuel line setup that flowed about a 1/3 of what it does now, but that seems like the wrong way to fix this... even if it did work. It also bugs me that my floats weighg 3.7g new when specified to be 3.6g and I'm not that far off weighing other things. Don't really want to choose another supplier and spend another $30-40 to find out those end up being the same though.
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Post by 90GTVert on Aug 26, 2022 20:18:02 GMT -5
The 28mm PHBH is a pretty close match for the 28mm VHST. Basically the fully round slide version with more standard floats. I looked at the 25mm that I was using on the TPR, but it's too small to fit the intake. The install would have been pretty quick if not for the need for more free cable than my current cable can provide. I didn't want to modify my current cable, but I had a new SSP-G GY6 69" cable around (I guess for GY6s with flat slides). I cut the sheathing back so it would work. My old cable from the Lectron would have worked, but I tossed it awhile ago because it was getting pretty rusty. The cable that the VHST was using is still on the bike. I just sealed the ends up and zip tied 'em so I can switch without re-routing that one. Doesn't look much different. The bowl protrusions even align with the worn out spots on the fender from the VHST.
It had a 125 in it from whatever I had it on last. That may have been long ago with Project 90 and the mild 96cc. I may have tried it on a 103cc with a Peace Pipe. Not sure. Regardless, I swapped it up to a 150 MJ after a very quick cleaning. It started on the first kick. Idle speed was about right. Idle mix was rich so I turned it in 1/2 turn. First attempt at a ride literally went nowhere. It was so rich that it didn't move. I swapped in a 135 and now it will get down the road. It's rich everywhere though. It was bad enough that I thought it may be a bad idea to go on the road, but I did it anyway. I was doing 66MPH breaking up like crazy without being WOT. These are the times when it sets in how strong this thing is vs any other setup I've had. The needle is all the way rich. That needs to change. The main jet needs to drop too. I wanted to sort this out today, but a friend stopped by and never left till basically dark so that didn't work out. This friend has been around the scoot in the garage plenty over the years, but hasn't really seen it run. I did the 150 test before he got there and quickly rode the 135 around the yard just to see that it would move. I said it's better, but it's rich. He said it looks pretty strong to me the way it spins the tire and tries to pick up when you hit it (grass and stones). I'm like, oh it always does that. Damn, he said. lol It's pretty fun to watch someone truly realize that I'm not just some scooter dork or kidding when I say my scooter is pretty quick for a scooter... and it was comparatively mild due to the richness.
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Post by Lucass2T on Aug 27, 2022 5:01:57 GMT -5
...I'm not just some scooter dork... Guess what, we all are no matter how quick or loud it is! But I love it!
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Post by 90GTVert on Aug 27, 2022 10:47:47 GMT -5
I moved the needle clip and then made my way down to a 120MJ in the PHBH. Runs pretty strong till it gets near WOT. Still breaks up there. The other time I've seen something similar to this was after some testing with the Lectron. I would get a warble at WOT and I couldn't figure out a power jet setting to fix it. Shortly after, it died and wouldn't restart from a partially melted piston crown and stuck ring. The engine is coming out next. I've gotta either have a piston/ring issue or something that I'm not seeing with the reeds trying to peep through the intake. Even to check the reeds, I have to remove the engine because the bolts won't come out due to hitting the engine mount tube. It could be that both carbs have float height issues or the wrong atomizers or something, but that doesn't seem as likely... more so in my mind because the VHST went from working to not working pretty suddenly, though a change in fuel flow did happen at the same time. I guess it could be ignition timing, but the issues are throttle position dependent and the ignition doesn't know where my throttle is. I guess at that rate the piston and reeds don't either, so it could be any of those things failing for load/stress related reasons. If you want to see what the TPR did with the Lectron on it before finally losing compression, here's that vid. The RC1 is breaking up worse now and mimics rich more than this, but it's sort of similar. youtu.be/Ac-QRbJFMBo?t=3565
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