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Post by alleyoop on May 16, 2014 12:47:27 GMT -5
I think your running lean at wot and is why it is getting hot. The reason I say this before the scoot would only do 50mph and now it is cranking out near 60mph. Also what type of AIR FILTER do you have on it? You may want to up jet the MAIN jet at least 1 size bigger.
Alleyoop
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Post by tvnacman on May 16, 2014 12:50:07 GMT -5
Alley a 743 sounds short for a 150cc no ?
John
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Post by alleyoop on May 16, 2014 13:24:14 GMT -5
Not if it is a SHORT CASE MOTOR, a Short case 150 takes a 743 20 30 belt. Now he can find out if it is a short case motor JUST COUNT the number of bolts holding the CVT cover, IF it only has 8 bolts holding the CVT cover then its a SHORT CASE motor if it has 10 bolts holding the CVT cover its a LONG CASE motor and a 743 would be to short it would take a 835 20 30 belt at least. Also the tire size would help if 10" tires then it is most likely a Short Case Motor if tires are bigger than 10" then the 743 is the wrong size belt. But it would help if we knew WHAT SCOOT he has the YEAR AND MODEL and the ENGINE NUMBER, most likely a 157QMJ.
Alleyoop
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Post by dev150cc on May 16, 2014 16:25:28 GMT -5
Hi guys,
Yeah, I can tell you for sure it's a short block 157QMJ running a 743 belt with 10 inch tires. Meiduo md15o-t4 (same as Tank Viaggio, roketa sicily, etc).
Alleyoop, I was thinking the same think about running lean, but the spark plug doesn't show it. And I attribute the top end gain strictly to variator. Recall it's rotating at substantially fewer rpms now with the new variator/weights. I may get a richer jet just to try, but I'll go through valve adjustment and track any possible vacuum leak first. I just checked the valves 200 miles ago, but it certainly warrants another look.
I'm running a stock air box with stock type filter that looks nice and clean. I'll check for an intake crack as well (you never know, it coulda snuck up on me since last ride)
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Post by tvnacman on May 16, 2014 16:49:33 GMT -5
I like running the Keihin and a pod that is what I run .
John
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Post by dev150cc on May 16, 2014 20:54:58 GMT -5
So I got home and checked all vacuum hoses - Aok, they all look fine. Fuel hoses too. And nothing kinked. But, I did a compression check just using the electric start (*see below) and it read  PSI tested 3 times. I rechecked the valves - 004 and 005 just right already. Could be a crapping out coil, which is easy to test with a swap. So, I'll read up this weekend on compression and see if being at PSI is a showstopper and time for a rebuild. I hope not, but it wouldn't be the end of the world on a small cylinder. May as well order an aluminum intake as well if I'm going to tear into it. *I attempted to use the kick starter to check any additional pressure with the CV cover off. Apparently that's a no-no because I broke the kick starter off. Looks like it's in there with a short piece of aluminum sleeve on the engine side, and supported on the outside by the cover. One more project to fix.... |
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Post by dev150cc on May 16, 2014 20:56:10 GMT -5
Regarding PSI, this bike fires right up, and before my belt loss incident, was running fine. I had driven it 25 miles to work that day before the belt blew.
edit - I forgot to hold the throttle wide open while testing. I'll have to re-run that test.
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Post by JerryScript on May 16, 2014 23:01:23 GMT -5
Yeah, plug is a healthy toast/slight grey. Not rich, not too light. I thought maybe it was fouling out at the time, as that's how it felt, but no, it's good. You are running lean. Your plug should have a nice brown coffee color to it. Grey is ok for many engines, but a gy6 will have issues with lean conditions, especially at WOT when the carb is not producing as much vacuum. I think it's time to upjet your main. |
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Post by dev150cc on May 17, 2014 0:02:09 GMT -5
I'm planning on pulling the carb out and doing just that. Aside from somewhat low PSI, everything else checks out.
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Post by tvnacman on May 17, 2014 7:37:52 GMT -5
is your muffler clear ?
John
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Post by dev150cc on May 17, 2014 9:06:04 GMT -5
Good question John. Yes it's clear, connected solidly and no leaks. I checked it out with the PDI.
I have a 102 main jet - just pulled it off. I have to work on a rental property today but will find a m/c shop in the area and pick up a few extras. I figure a 110 and 115 would be good for experimenting with first.
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Post by retrobrian on May 18, 2014 11:20:45 GMT -5
I am confused... I have a post running in respect to variator weights. I want to change mine. Im being told that if I go to lighter weights ie 12 g.... the rpm will rise and I should get lower top end speed with better take offs. Heavier weights higher top speed. which is it?
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Post by phssthpok on May 18, 2014 12:32:10 GMT -5
You are not the only one confused. When I tore into my CVT, I weighed the rollers. They *all* came back at 12.8g with minor wear just beginning to show (so I'm presuming a 13g initial weight). I can't imagine an 18g weight in a 150cc engine. Something that heavy would probably be trying to close the variator at idle and REALLY kill the bottom end acceleration.  |
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Post by JerryScript on May 18, 2014 21:44:39 GMT -5
The variator gets pushed out by the weights moving against the ramp plate. Lighter weights take higher RPMs to push out the variator, heavier weights push it out at lower RPM. The end result in relation to power is when you hit the engine's power band, sooner (lighter) or later (heavier).
When balanced together with the appropriate clutch springs, contra spring, and gears, you can turn your scooter into a jack rabbit that will pop wheelies, or make it fast enough at the top end to take on the freeway, or a balance of the two that suits your riding style.
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Post by dev150cc on May 19, 2014 0:53:29 GMT -5
Weekend update.... Well, I picked up a few jets and jetted up from 102 to 115. The carb is super-clean, no debris, and checked the pilot jet while I was down there. Float height looks good, given an eyeball inspection. Did a mild suction on the petcock to make sure it's triggering gas flow. Took the gas cap off to make sure it's not suction locked. Checked the gas tank overflo hose going to the little emissions do-hicky to make sure extra gas wasn't going into there.Checked all the vacuum hoses, intake manifold, etc. All looks perfect. I did a compression test and got a rock solid 140 PSI (I had PSI but forgot to open the throttle). Supa! For all intents and purposes, these scoot should be all systems go. I took it back out for a spin after the 115 jet install. What I thought before was overheating re-manifested itself leaving the neighborhood for the test ride, right from the get-go. And I know it wasn't overheating. If I try to give it any throttle at all, it just misses. But it doesn't feel like a lean/rich stumble, just missing. If I go nice and easy on the throttle, it will ease its way up, but I dare not goose it whatsoever or it will so that "miss". Makes me wonder if I have a spark issue at this point, because everything else looks great. I bad spark plug boot would be plausible, if not the coil. I've never had a CDI go, so I'm not sure how it feels, but that's a possibility as well. I'll go spark plug back to the CDI tomorrow with spares and the new 12 gram variator setup. If it's not spark, I'm going back to the old variator with the heaviest weights I have - 13 gram. The old 17 grams were too worn to reuse. So for all intents and purpose, I have to say carburation is not an issue. Compression is not an issue. Air intake is solid. Vacuum hoses and connections are all new/sound. Exhaust checks out. Gotta be spark or variator I figure. Keeping in mind, none of this occurred until last week when I lost a belt and decided to try the Koso variator and 12 gram rollers from the stock 17 gram rollers and variator. |
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..BAD TO THE BONE..
PSI tested 3 times.
