tysta
Scoot Member
Posts: 79
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Post by tysta on May 30, 2024 22:17:31 GMT -5
Started another day off right…  The atomizer came out when I removed the main jet, so I went to snug it good with a 10mm socket on a screwdriver and it snapped. Screw extractor got it out easy enough. That’s the standard 30 hole. I ordered another from treatland immediately (promo code mydio for 15% off till 6/4/24). I have 20 and 40 hole here. I had at least a few comments on vids to use an atomizer with no holes or less holes on these and of course one saying more holes just to make it more difficult. My thought was less holes anyway if I tried one, so I guess I’ll put the 20 in with the 205MJ. So much for 1 change at a time. i never ran more than 165 Mjet with a pwk35mm on the engines i built (100cc3 2fast) |
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tysta
Scoot Member
Posts: 79
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Post by tysta on May 30, 2024 22:24:47 GMT -5
Zach right? I found him on Facebook and have been chatting him up - SUPER wild build. He is getting some downright amazing times. He said he was running some type of stupid small squish like .1mm LOL! You're running a Polini PWK right? I switched to the 30mm polini pwk on my bike last night and think I need to up the main jet. I'm at a 138 now and it feels like it wants a little more. Been dealing with the spark issue for ages that I just now fixed so hoping I can get the bike running less hot now that it can be ridden WOT. For a while though seeing your posts here and the temps I was, I felt like it was the PWK carb. Some people have been saying the Polini PWKs are hard to tune and get "right" but I think for the price, these are amazing and hope I can get it dialed (and you too). That’s him. Yeah, Polini PWK. Some people think PWKs and flat slides in general are the best thing ever and some don’t like them. So far I’m surely the latter. For now, the scoot just isn’t responsive like it was with the smaller VHST. When I’d normally be picking the wheel up just rolling in the throttle it’s not. If I grab throttle quick it lags instead of jumps. Not saying it’s in great tune here for sure, but that’s what it’s been like most of the time. If it doesn’t get better then this then the big carb may improve acceleration times but it’s way more fun when it snaps. For all of the people that talk about throttle response with a flat slide, they should ride one like mine with the VHST and see how sluggish it feels. No one that has ever seen it in person says it could use better throttle response. LOL so with a bigger carb most times you end up lossing intake speed. but also if you have something wrong with timing it will do similar symptoms like i mentioned before you can easily check your work set the static at 0 then make a map with 16degress all the way cross start the scoot set the idle at 4k and use you timing light and check the ignition advance from there you can make adjustments |
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tysta
Scoot Member
Posts: 79
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Post by tysta on May 30, 2024 22:38:10 GMT -5
Alright, so I started yesterday out with a 205 main jet, up from a 195. It ran very well. My best run ever is 9.67 and it did 9.73 on one run with a 6.95 0-60. I suspect there's slightly more with fine tuning of the CVT, but a good result for me. The mix ring looked pretty good, but I wanted to go up on the main jet to see if it liked more fuel. It still ran well, but the mix ring was much lighter. Odd. Must be a fluke or a main jet improperly marked or something. Not sure. I went up to a 215 MJ. It died after the 2nd 1/8 mile run. Times weren't terrible, but not as good as they were and my 60ft was 2.6X twice... which is way slow for me. I suspected it may be from the lean hanging idle that I have with the JJK needle... but I haven't wanted to fix it because I was focusing on WOT first. It didn't die during WOT. I was out of the gas, coasting to a stop or to turn around slowly and blipping the throttle to try to lower the RPM and it went to idle and then just died. Felt low on compression so I pushed it to the shade, tried to kick more, and then called for a ride. Here's the last run... I never do plug chops... well, not a lot. They're basically for when I struggle, because main jet tuning typically follows curves... performance, EGT and sound/feel. It's a waste of money to cut up plugs after every run, or that's how I usually think. Well, thankfully I had been using new plugs for each jet, because they show the story of the oddity of my PWK experience. Hopefully it will let you blow this up to full size. You should be able to see that with a 195 MJ, I got a smoky mix ring. The 205 looked pretty good. A little thin perhaps in one area, but it was dark and thick on the other side not shown. The 210 was significantly lighter and looking lean. Again, I thought it was a fluke because that's now how adding fuel is supposed to work. The 215 barely had any color to it at all and appears to be very lean.  So I can go up and watch the plug show me what I expect to a point. After that point the plug shows leaner and leaner rapidly. EGT didn't tell the same tale so obviously. These are all observed at 60MPH during acceleration runs and averaged. The 195MJ was 1184F avg, 205 was 1199, 210 was 1182 and 215 was 1203. It stayed pretty similar regardless. This defies logic, however it seems possible perhaps a couple of ways to me. It could be inconsistency in main jet orifice size. I melted a piston long ago by going up in jet size to be safe on a long ride only to later find that a larger marked jet was actually smaller than what it replaced. Those were Chinese jets and mixed stuff though. The 205-215 are all Keihin. Sizes below that are Stage6. Stage6 doesn't sell the larger sizes to my knowledge. The other thought is running out of fuel. I have ran a clear bowl as shown just prior to this post and it did not appear to me that the fuel level was dropping during acceleration... or if it was, it was minor. That said, the clear bowl is slightly larger and designed a little different so maybe that makes a difference? Seeing how much fuel was in the clear bowl makes me think it really shouldn't run out of fuel with the main jet all the way at the bottom of the bowl. I've also never, that I know of, experienced fuel starvation to a point that it doesn't lose power during a run but leans it out sort of consistently and it dies after. I would think you'd get a mixture ring forming on the plug from the early stages of runs at least if that were the case... and I did do 3 whole runs and it only died after that. When the VHST would run out of fuel, it was often a quite obvious bog and then would recover after sitting at idle or low throttle briefly. Those are the only things that I can think of at this point that would make it show leaner with supposedly more fuel though. I checked earlier and I have ~65psi on a compression test. I had about 150 when it went back together. Oh joy. This will drive me nuts if I don't get it right. Regardless, I'm convinced that the stars just had to align to make it more difficult for me than everyone else. I don't think there's anything inherently wrong with my setup. Ryan nor the other local guy are doing anything much different and neither thought the carb tuning was a big deal. I've gotta see how bad the engine is of course. Thinking ahead, I could level the carb out as John has suggested multiple times. It would be way less likely to starve. But then... how do you explain when the engine died in the video of the clear float bowl while there was plenty of fuel and a 200 MJ that should have been at least capable of letting it run some acceleration passes? I would like to look over and measure the float bowl capacities. I would also like to check main jet sizes, but don't have anything in that range. Not sure if I can use the lathe to make checkers as I've found small diameter stuff likes to flex too much in the past. I've gotta get this figured out soon before I have to do a 4T swap to save money. 😱 i just watched the video i can ear the engine start to fail. you can have more than one problem there. i can have fuel foaming on the bowl to. but again for experience seen this more than one time were some guys have the ignition not set up correctly it will do that it only wants a huge jet but it starts to seize after a but and when the jet is so large it washes the plug and every thing else then people thing its running lean but its not its just so loaded with fuel to keep up with the ignition its washes away everything leaving no deposits |
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Post by 90GTVert on May 31, 2024 4:34:16 GMT -5
i never ran more than 165 Mjet with a pwk35mm on the engines i built (100cc3 2fast) Most people with the RC-One 94cc and a 34mm PWKseem to be 185 +/- 10... but I kinda gave up on fitting in. After so much time and expense, I was just hoping it could work whether the jet size fit everyone else's norms or not. It does seem odd to me as well though to need larger jetting than common. Here's where this argument doesn't work though... I put the 28mm VHST back and actually needed a little smaller jet than I ran for a long time prior to the PWK. It also went back to being every bit as responsive as before when the VHST was in place. so with a bigger carb most times you end up lossing intake speed. but also if you have something wrong with timing it will do similar symptoms like i mentioned before you can easily check your work set the static at 0 then make a map with 16degress all the way cross start the scoot set the idle at 4k and use you timing light and check the ignition advance from there you can make adjustments I probably should check timing that way just to be sure and even mentioned the idea of a flat curve on my own as well during the process, but it's more time and this thing is quite obnoxious when you're standing beside it realizing you have neighbors as you rev it on the bench. lol I'll probably wind up doing it at some point just to be sure what's happening since there is somewhat minor discrepancy in the measured vs plotted curve. I know it's common to lose snappiness with larger carbs, but it doesn't make it less disappointing. It did improve some with jetting that it liked more, and it was still too lean part throttle, so there may be hope even if not related to something else. i just watched the video i can ear the engine start to fail. you can have more than one problem there. i can have fuel foaming on the bowl to. Why don't we see that with the clear bowl? Jetting requirement or how it acted didn't seem to change from the clear bowl to the standard bowl. I guess if fuel is significantly lower in the standard bowl... but if it can maintain enough to keep fuel all around the jet I would think foam would be above that level. 🤷♂️ The only time I'm sure I've had foaming was back when I first tried to use a solid support bracket for the VHST and suddenly it acted up (not like this though) till I put rubber in it and then it was fine. It was dropping RPM on the big end with the VHST too though, and TBH I'm not sure if it's CVT or engine related because if the shimming gets too thin it can drop RPM at speed. With the way it has been acting it starts to turn into too many things to test and too little time... especially with farmers out in my usual spot near home more often ATM so then I'm riding 15-20 miles to do a set of test runs sometimes rather than trying to irritate people that I think otherwise don't really care 3 miles away. ~15-20 miles round trip ain't much to me, but it's a lot over and over when you're trying to accomplish something. Even out here in the country, it's tough to find straight spots with no houses directly in front of them and hardly any traffic. but again for experience seen this more than one time were some guys have the ignition not set up correctly it will do that it only wants a huge jet but it starts to seize after a but and when the jet is so large it washes the plug and every thing else then people thing its running lean but its not its just so loaded with fuel to keep up with the ignition its washes away everything leaving no deposits I could see washing with the VHST. It would go beyond the mix ring and start turning into a smoky look as if it were diluted by fuel. Pretty much the same as looking at the top of a plug when the mix is rich part throttle and it washes it. This is not like that. The plug comes out totally dry and there's little color anywhere. I guess whenever the new bowl screw/cap comes in, I could see if I could get a barb on the stock one for a clear hose to be used for level observation for testing. Not as good of a visual, but at least it could only be drawing fuel from right around the main jet so if it shows no fuel then there's a problem for sure. I'd consider just running the clear bowl, but generally they are said not to hold up to regular use for too long and since this setup has the bowl against the fender the plastic bowl will wear through quickly without redesigning the intake. |
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Post by 90GTVert on May 31, 2024 7:52:20 GMT -5
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Post by 808ministroke on May 31, 2024 21:29:58 GMT -5
Well at least the scoffing below the transreport is beneath the compression part of the so there's a silver lin...., I mean there's a Nikasil lining here .
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tysta
Scoot Member
Posts: 79
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Post by tysta on Jun 1, 2024 20:23:47 GMT -5
i have a ring if you need. but also it seems the cylinder was not up to temp almost if the piston expanded too much before the cylinder |
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tysta
Scoot Member
Posts: 79
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Post by tysta on Jun 1, 2024 20:27:44 GMT -5
after inspecting better the photo from the top of the piston it visible the its knocking
what is the squish you are using and do you have photo of the method you use to place the Tin?
also i keep insisting on your timing
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Post by 90GTVert on Jun 1, 2024 22:06:37 GMT -5
but also it seems the cylinder was not up to temp almost if the piston expanded too much before the cylinder This was after probably 8 miles of riding at least and it was after the third 1/8 mile pass after that ride to the spot. I let it warm up while I get my gear, the dragy and camera on before riding. after inspecting better the photo from the top of the piston it visible the its knocking what is the squish you are using and do you have photo of the method you use to place the Tin? also i keep insisting on your timing It’s hard to say if it’s knocking WOT or part throttle, but it’s too lean part throttle. It needs a needle adjustment or change, but I was trying to get through the test runs just to be sure nothing changed results, watching EGT while commuting. I can tell you that I’ll at least be moving the clip next time before riding. It’s 0.55mm squish with Malossi recommending 0.55-0.6mm. Same range I’ve used for 2 years that wasn’t a problem till the PWK. I've shown squish check before, but solder is taped all the way across transfer to exhaust. If it’s timing it would seem like it should be related to timing only with the PWK. I get that timing requirement changes with the incoming charge, but I don’t see how that would explain why it goes lean with larger jetting. It ran quite well and did t die on me with a 205 and then by 215 it’s very lean and dies. For comparison, here are three plug chops from the VHST just prior to the PWK being put back on. Notice that 140 looks good on the mix ring, the. The larger jets appear to have more fuel as you’d expect and they are washing the area some. 150 gave me best results prior to the current timing, so it gets smaller on jet size… meanwhile the PWK gets very lean rapidly above best results and dry and still needs bigger jets than most…. but not too big or it will lean out.  I can check timing once it runs. At least if I can verify what I see with a flat “curve” that eliminates one thing potentially. I’m not trying to be argumentative here. I assure you I appreciate input because this is frustrating and expensive, which are the same reasons that I’m trying to think it out before I get it going again and do more tuning attempts. Everything I’ve tried, aside from just using the 28mm VHST, ends in piston failure and everything involves multiple timing changes, 2 different ignitions, multiple pistons and a new cylinder kit, jets from 175 to none at all, multiple needles, pilot jets, alternate needle selection and jetting process, clear bowl observation, and more that I’m sure I’m forgetting. I can put the 28mm VHST back on and ride it… but all of that can’t make the 34mm PWK not blow it up. A smarter person would just use a VHST and go on with life. |
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Post by 190mech on Jun 2, 2024 8:50:45 GMT -5
I also noticed the "sand blasted" look on the edge and down the side of the piston indicating detonation. I think Wobbly at KiwiBiker says the EGT gets lower when det starts and only takes a few seconds to damage the piston. I dont have any answers about this issue except saying all the high end kart racers have some type of a det sensor to alert a melt down..
Remember the days of droning along for hours on the simple 90+ cc AC builds? The wilder they get, the harder they bite you..
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Post by 90GTVert on Jun 2, 2024 11:52:50 GMT -5
I also noticed the "sand blasted" look on the edge and down the side of the piston indicating detonation. I think Wobbly at KiwiBiker says the EGT gets lower when det starts and only takes a few seconds to damage the piston. I dont have any answers about this issue except saying all the high end kart racers have some type of a det sensor to alert a melt down.. Remember the days of droning along for hours on the simple 90+ cc AC builds? The wilder they get, the harder they bite you.. I looked at the listing you sent for a knock sensor last time you replied. This one : www.ebay.com/itm/116174503000?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Yyq69gMIScW&sssrc=2047675&ssuid=GXr2BhbbTJC&widget_ver=artemis&media=COPYSays it works with these sensors : Honda #30530-PV1-A01 BOSCH 0 261 231 188 Delphi AS10134-12B1 I was thinking about trying it with the Bosch sensor : amzn.to/4c2eMyDThis is what I had in mind for mounting. The outer head or cover uses 3 cap screws that recess into the cover and threads are in the cylinder. I was thinking I could use a stud, the copper ring that Malossi uses under each cap screw, a spacer to fill the void where the head of the cap screw would be, then the sensor on top and a nut. Seems like it should then be sensitive to the outer head and the cylinder at least and hopefully work without causing any sealing issues.  EDIT : Ordered the gauge and sensor. Gauge says basically 2-4 weeks, but I didn't see anything else near that price that looked good to me. The sensor looks like a fuel injector connection to me so I also ordered a Bosch EV1 pigtail. amzn.to/4c3FNC0 |
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Post by 190mech on Jun 2, 2024 18:29:16 GMT -5
Looks good! Wobbly post # 39439 (team ESE thread) shows his setup on the TM kart engine, also tells how the sensor works..
I might have asked this before, does that pipe use a tailpipe nozzle/restrictor? If so what is it's ID in relation with the stinger ID?
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Post by 90GTVert on Jun 3, 2024 7:41:42 GMT -5
Looks good! Wobbly post # 39439 (team ESE thread) shows his setup on the TM kart engine, also tells how the sensor works.. I might have asked this before, does that pipe use a tailpipe nozzle/restrictor? If so what is it's ID in relation with the stinger ID? Thanks. This one doesn't. It's a welded on stinger. I did have one comment on YouTube tell me I should try a pipe with a larger stinger because it may be that moving more volume with a larger carb has put me just over the edge. It could again go back to Ryan, the local and countless others running 34mm carbs with the same setup without issue and would a stinger size make the plug look lean? When I have had an obviously too small stinger on something in the past (I think I tried the 70cc MRP exhaust on a 90cc) it clearly damaged the piston from the exhaust port side. This doesn't look like signs of that. Seems like detonation indication all the way around the crown rather than heat coming from one source, but I guess if it were a mild sizing issue it could be enough to heat the mixture overall and make that more likely. Just not sure that's the most likely candidate right now. My thought for post-re-assy is to use the clear bowl. Possibly alter how the carb sits if I can get it to not hit the fender so it won't rub the bowl and wear through the plastic quickly. The plastic bowls may hold up well enough at $12 that I could replace periodically if needed as long as there's no contact. I checked the plastic bowl and the aluminum original bowl by letting them fill at different angles and draining them. Original holds ~30cc at a 30 degree angle and ~35cc flat. Plastic bowl holds ~50cc either way. I retested the plastic because it didn't make sense how 1 changes with angle and the other doesn't really, but it came out the same. It may be a cc or 2 more fuel flat, but I'm not using a super precise method because within a few cc is close enough for this. Only thing that sucks with the plastic bowl is that there's no easy access for jet swaps. If I ever get it to work though, I don't typically have to swap jets a lot.   I'll also probably do the flat timing curve to see how my numbers match with what it's supposed to be. |
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Post by billwill on Jun 3, 2024 8:51:00 GMT -5
Got a link for that clear bowl? I've been thinking about trying one myself but haven't been able to find one with a confirmed fit specifically for the Polini PWK.
Very intrigued in this whole problem and following closely since I have a Polini PWK30 that seems to make my bike run hotter than it should. Also dealing with the mysterious lack of ceiling for main jet. This thing keeps taking more and more of a main jet and gobbling them up. It ran (very lean) with a 128 main and I've since upped it to a 148 where it was still running clean and crisp, though just a bit hot on sustained WOT runs.
I installed the MVT dd over the weekend and that seems to have cooled things down a bit, interestingly enough. Going to try a 154 main next and see how that takes but it seems awfully large for my setup.
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Post by 90GTVert on Jun 3, 2024 12:51:44 GMT -5
Got a link for that clear bowl? I've been thinking about trying one myself but haven't been able to find one with a confirmed fit specifically for the Polini PWK. There are more on there. There are some that don't have the power jet barb that you need to cap if you don't have one. Some have a drain. This one worked and had residue in it for a month and hasn't deteriorated that I can tell so I just reordered it. Very intrigued in this whole problem and following closely since I have a Polini PWK30 that seems to make my bike run hotter than it should. Also dealing with the mysterious lack of ceiling for main jet. This thing keeps taking more and more of a main jet and gobbling them up. It ran (very lean) with a 128 main and I've since upped it to a 148 where it was still running clean and crisp, though just a bit hot on sustained WOT runs. I installed the MVT dd over the weekend and that seems to have cooled things down a bit, interestingly enough. Going to try a 154 main next and see how that takes but it seems awfully large for my setup. Considering most with a 34mm are 175-195 MJ, 150 doesn't sound crazy to me at all on a 30mm. My 28mm VHST is currently liking 140-ish, but used a 150 for most of it's time and that's what Malossi sends it with. Not sure what everyone else uses with a 30mm PWK though. |
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