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Post by stellarfoxy on Jun 26, 2015 12:45:21 GMT -5
Ahh! I can get another tach, this scooter didn't come with most of it's parts, and what it did have was abused so I'm not surprised something else is messed up. I tuned it yesterday with the gauge sitting at 2000 rpm whatever that is in real life. I checked for vacuum leaks last night and everything is sealed up nicely. still need to look at the plug though to see what it's color has to reveal. I'm thinking, based on suggestion here, I may be too big on my jets? granted, they are ebay jets and apparently that may or may not be accurate, so I'm assuming it's just kinda feeling around in the dark until it runs correctly.
I will look at adjusting the float tonight if I have time, might drop down to a smaller pilot and/or main jet if the plug looks ok.
anything else I should check? and any recommendations on a smooth clutch/bell combo? or a place that sells legit Taiwanese-or-better carburetors?
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Post by stellarfoxy on Jun 25, 2015 22:45:46 GMT -5
first thing ive ever edited on a cell phone or uploaded to the tube. how do i adjust the float? and the clutch grabbed at around 2k on the throttle, didnt check how high it had to idle to grab
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Post by stellarfoxy on Jun 25, 2015 21:47:09 GMT -5
the clutch is being kind of chattery at the moment as if it's glazed, but I'd say maybe 2500? i checked the bowl yesterday after it died and refused to start again. i have a manual gas cut off now so i dont think i can check it anymore because the bowl will fill up immediately.
i was thinking the cam would have an effect on jetting not idle rpm, like since more air is being pulled in more gas would be required. in regard to idle speed, I'd think low rpm would be worse with a bigger cam. can i upload a video here? i can show you the low idling and maybe my tach is just off
i going to check the plug to see what color it is, I'll make a short video and try to put it on youtube for you to see
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Post by stellarfoxy on Jun 25, 2015 20:49:06 GMT -5
just got back in from a 15 minute ride with a 38 pilot and 125 jet. set the idle to 1800ish then backed the screw out, tightened it, but no change until it dropped from being too lean. took the screw back out to about 2.5 turns again and drove it a bit, it still wants to cut off when i give it a sharp twist on the throttle when its warm, then not start for a few minutes and will onl start if i drop the idle screw back to where it would idle at 700-800rpm.
it may not matter but i have an a9 cam also, apparently that designation can mean a lot of things, this one was roughly double the lift and a bit more duration than stock. also, are the pilot jets numbered backwards from main? my sizes were 42<40<38<35, smallest to largest holes. the stock ones were smaller than the 42. i may switch it back out with a 40 or 42 but it didn't seem to change anything anyway. I'll let it idle tonight and check the plug.
also, could overheating cause this symptom? my fan shroud intake hole is missing the grate thing, might not be pressurizing the air properly to cool everything but I'm pretty sure that's secondary to the carb being wrong.
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Post by stellarfoxy on Jun 25, 2015 18:22:12 GMT -5
ricardo- i thought so too, but the carb is new and I've always had a filter on it. how should i check if it's clogged?
geh- i thought that same thing about it idling so low. i was kind of proud of the little thing for doing it really. the tach is kind of slow on mine and i assume accuracy is relative but I'll get it to 2k then tune. i just got a set of slow jets in today, i think 32-45, should i try upping that first and going back to the 125 main before i warm it up?
thank you again for the help guys, your patience and knowledge is greatly appreciated.
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Post by stellarfoxy on Jun 25, 2015 9:58:58 GMT -5
wow, I was way low. I get off work at 6, I'll drive it around and try tuning it that way. Thank you for pointing me in a direction man. will it not be harder to start with the screw set to idle at 1700 though? or will the af screw being turned correctly help that?
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Post by stellarfoxy on Jun 24, 2015 22:26:49 GMT -5
Hello everyone! I a 157qmj and appear to have the somewhat common "won't start when hot" issue. i think I've done most of the diagnostics, but everything seems to be right. Valve lash is .004 intake and .006 exhaust cold, compression is 125psi warm, no oil leaking on the cdi (or anywhere for that matter), strong spark in all conditions, and the timing is correct. i finished a complete rebuild on the engine a couple months ago, replacing the crank, piston and rings, gaskets and seals, head, timing chain, cam (a9), plug, coil (orange), cdi (orange), carburetor, intake manifold (aluminum), intake pipe and filter (uni), exhaust (header and free flow muffler), i have a breather on the pcv, fresh upgraded vacuum and fuel hoses/ filter, i can't remember anything else right off. i honed the cylinder also since i was already in there. carb main jet is 130, idle jet is whatever the carb came with, it idled best with the gas screw being like 2.5 turns out or so. it can idle around 700rpm without dying but i have it around 1000.
tl;dr, this thing gets weird when it's warm. it almost left me stranded yesterday but after it cooled off for a few minutes i fiddled with the idle screw, it cranked and i rode it home, it pulled hard all the way. i rode it around the hood today for about half an hour, not going hard but not babying it. when i got back to my driveway it dropped to idle fine but when i opened the throttle and it died and wouldn't crank. i quickly checked compression, spark, etc while it was warm, everything seemed ok, but maybe 125psi is on the low end?
the plug was brownish but dry and didn't smell of gas. however, the oil kinda does have a gassy smell, so i might need a manual fuel valve soon, but i don't think that would be related?
anyway, if anyone has any ideas what to check, I'm extremely open to ideas. i will say that i had a 125 main jet in before and it went for hours with no issue but the plug was white-ish so i took it to 130. also this is my second ebay carb and they both might be complete crap, but this one ran better so its what i'm using. so that might be something to try if someone can recommend where i can get a not-garbage carb for reasonable money. most keihin are knockoff, even the oko and hoca ones have knockoffs now, my eye isn't keen enough to tell the difference.
... and uh, if i missed anything, don't hesitate to ask.
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Post by stellarfoxy on May 16, 2015 18:38:24 GMT -5
I've done work on a lot of different Japanese cars and a couple of European and American ones, they are all complicated and efficient and start quickly and control emissions and whatever, this engine wants nothing to do with that. it's simple. and it's beautiful for it.
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Post by stellarfoxy on May 16, 2015 18:35:32 GMT -5
haha I found my tool collection growing from this, the handful of special tools plus I got a hone and gear puller, I don't think I needed anything else? I bought a compression tester just in case also which was helpful. these engines are amazing in their simplicity though, I was surprised at how well thought-out the design is, even though it's apparently around 30 years old? I felt very little hesitation in my decision to just start ripping it all the way apart. everything makes sense on it, everything has a purpose. it's also easy to see which modifications affect the engine and how. I'm completely enamored with the design lol
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Post by stellarfoxy on May 13, 2015 9:16:23 GMT -5
Apparently that's the exact factory procedure, so at least you've got that? they just have the luxury of hitting those threads the first time so they don't come apart!
did you end up having to replace the crank?
I'm struggling to find fork seals right now. I have a set I got off ebay that are correct size, but in the removal process one of the dust covers got destroyed and I cannot find those anywhere in the US. there's a few available in europe, but next to nothing here. Apparently a 2003 honda cb250 has the same size forks and dust seal, but even that is hard to find parts for. If anyone has any leads on where to find 31mm x 43mm dust seals, hook me up with a link! I can't find em anywhere!!
EDIT: found them. apparently the 31/43 is a strange size. had to order them out of Australia.
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Post by stellarfoxy on May 1, 2015 16:58:55 GMT -5
What I did was slide the magnetic flywheel on the other side with the woodruff key in place to keep it from turning, held that still with a device ebay describes as a "FlyWheel Clutch Hub Rotor Sprockets Spanner Wrench Holder Adjustable Tool" which prevented the crank from turning, then installed the spacer and variator and cranked down on that nut. I was communicating with a gy6 guru who said that most of them are assembled with impact guns and are extremely over-torqued from the factory, which is why they are difficult to remove, but they don't need that much to stay. Since mine was mostly a spacer I just tightened it up and it worked perfectly.
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Post by stellarfoxy on Apr 30, 2015 22:46:44 GMT -5
also, fun fact about the rear axle nut (which was missing, along with the spacer) it's a weird size abd hard to find locally, but the passenger side rear axle nut from a Mazda 323 is the exact same size and.. well, made to take more abuse. plus locally sourceable and cheap.
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Post by stellarfoxy on Apr 30, 2015 22:43:54 GMT -5
thanks Ken! there isn't a piece on that engine I haven't laid my grubby hands on at this point. I disassembled the forks tonight and found the seal size, surprisingly difficult to find online- 31x43x10.3 in case anyone was wondering.
dmartin- hello and thanks for appreciating that lol. I never thought it would take so much effort, but once you get so far... why stop now?! as for the kick start gear, I didn't. the mechanism was all jacked up and I didn't feel like kick start was worth it when it takes so much effort to start anyway. the starter has been through trying to start this thing with the timing off, so bad it melted the filter a little. I figure I'll just keep a really close eye on the starter lol
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Post by stellarfoxy on Apr 30, 2015 16:58:20 GMT -5
Hello all! almost a year ago, I acquired a pile of plastic and metal that had apparently been abandoned behind a friends rental property. It was missing the entire intake, exhaust, ignition, various body panels, random nuts and bolts, vacuum/fuel lines, etc. What was left was mostly broken.
Naturally, with no small engine or motorcycle experience whatsoever, I decided I could get it running and have something fun and practical to ride around on. So began the long journey, which was held up a few months by acquiring a title, but that was ultimately a success. hooray!
...But this was no ordinary scooter! it turned out to be a cursed powermax 150cc that had been ridden hard for at least 5000 of the 5500 of whatever distance unit the odometer shows and appeared to never have had any maintenance done to it. upon visual inspection, the rear tire had holes in it from burnouts or locking up brakes and virtually every missing part had been removed by force. after replacing damn near everything simple on it (double on some parts, can't be too sure!) and even replacing the timing chain (without removing the head!!), I had come to find out that the cam gear marks refused to line up, and the reason was because the gear on the crank had slipped. how does that even happen, I don't know. unless the previous owner jammed a stick in the exhaust valves while it was running? anyway, I jumped right in and hap-hazardously ripped the whole engine apart to replace the crank. I figured it was easier than trying to realign the gear, and they are only like $50 so what the .
tl;dr, it runs strong now with an A9 cam (whatever that means, it was huge lift compared to stock), uni filter, knockoff keihin carb with 110 jet, dr. scoot rollers, rainbow color straight-thru muffler, orange adjustable cdi, orange coil, new badass fuel and vacuum lines, new piston, new crank, new head, new gaskets all around... I'm way more knowledgeable of this engine than I ever intended to be. any questions about the painful build, lmk. I did gain some interesting cross-referencing info I'll contribute later.
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