Hey guys, I put a 38mm carb on and it rab AWSOME!! I have alot of other mods aswell. The wheeler reved alot higher than it used to. Well heres the mods incase it matters. 60 over wiseco and bore all fresh, 38mm carb, airbox mod, K&N filter, HPD trail pipe, Boyeson rad valves, Just put on a new FMF Turbine Core2 after all this happened, And a ufo in the carb. Well I put the carb on with great recommended jetting. Worked great-was doing runs to see if I was running lean anywhere or really rich. 290 main, 3cut slide, 1 turn out on air, 5 on idle screw, and 2 down on needle aswell as a 35 on pilot(first time w/o ufo then/now 25 w ufo) I had the stock needle which was richer. Well I did the pilot jet test and was perfect! then did the needle test run and also came out perfect, then went to do the main jet(full throttle run) Had it wide open and was starting to get it up to rpm and it just went blaaaaaaa! As soon as it stopped I gave it a yank to see if I had compression or to see if I seized it up. Pulled over just as it did when new. I have since taken the head off, reed cage assembly and exhaust. I wanted to see if there was a hole because it wouldnt start, looked at the skirts and cylinder wall and it looked excellent. Plug was very dark after I pulled it from it dying on me. So i wasnt running lean- I tried 5-6 new plugs in it so far and also drained the base to make sure there wasnt too much fluid to where it wouldnt start. With the head off I checked to see where the firing was taking place. It is firing either exactly bottom dead center or close to it, if it is close it is when the piston is going down not up. so In turn it is very advanced. Can the timing be advanced that far? Or is something broken? I would like to fix this thing as it has been not running for a long time(week or so) everything else is good, I sat outside for the last half hour just to be 100% sure it is not firing where it should. Any help is most appretiated, everyone has been a huge help to me so far! Thanks alot! Brian

 

Have you checked your flywheel? If that came loose, it would effect your timing. Pull off the flywheel cover to make sure everything is in good shape under there. That is where your spark comes from I think.

 

Well yes thats where the spark comes from. the magnetized flywheel spins around a staor that has coils, the coils are very close to the flywheel and the coils pickup electrical current as the flywheel flies by it. I checked it all oout earlier and well its an odd thing. The wheeler is actually firing at bottom dead center AND at top dead center! What could be wrong??? I dont know why it is doing both! Thanks, Brian

 

If you have a magnet that came loose or ,if the flywheel key was sheared it will cause some crazy backfiring.You should also check the reeds,cracked or a missing petal will cause some popping as well.

 

what is the compression right now?
i'm sure it is because of your ufo,the ufo is for round slide carb only,and the tmx 38 is a flatside carb,
remove that goodies,check your stator plate.

 

Im not stupid enough to put a ufo on a flatslide!This is a vm(roundslide)carb. Ufo has nothing to do with it-its a spark problem, it is firing at an advanced top dead center and at bottom dead center. What causes this? There is no other problems as far as not having spark, leaking, hole in piston, low compression, broken reeds, bad head gasket, bad crank seals, fluid in base, bad ground, warped head, ect. This is a spark issue, what would cause it to fire twice? I will pull the recoil off and see whats up with that. Thanks, Brian

 

I took the recoil off and nothing wrong inside allthough I didnt pull the flywheel off. Everything looks good. I pulled over the wheeler when the recoil was on and it was firing, This was without the carb or reed/reed cage assembly on, there was some gas in it but not alot, I pulled it over and about a 3 foot flame come out of the intake! This was because of it firing at top and bottom dead center. Also I had lost my key so where the key hooks up I unplugged the ground to have spark, is this why it is firing out of order? It shouldnt be the reason tho, I think this is why the wheeler stopped running0it was burning up the fuel before it even got to be compressed! I didnt hear anything as far as bangs booms backfires ect. It did have alot of rev to it, Do you think I ruined the cdi because of the high rev and now is firing top and bottom? Thanks alot, Brian

 

Take the flywheel off and mke sure the key has not snapped.

 

I shouldnt have to take the flywheel off to see that right? Just spin it and it moves the crank, I dont have a puller for it so cant take it off. I think its a cdi or some crap, it is consistantly at tdc and bdc.

 

you might be able to see the key way if you take the nut off. problem is the fly wheel will seem firmly secured as the tend to get fairly rusty but under acceleration could have easily spun out of alignment.

if your using the ufo take it off for now they tend to reakl havoc jetting this motor.