JS550

Just bought a js550 it has a milled head, msd total loss analog, sbn44 w/125 high & 100 low, 2.3 seat and 65 gram spring. Won't stay running just kicks over for a few seconds and spits and sputters. How do I check timing. It likes to backfire out the carb and exhaust. Also has kerker full exhaust... What initial settings for carb I'm so confused.

JBones

try a new set of plugs first. make sure the fuel is good. Prob be better of asking this in the vintage forum though...

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87' Js550 ~ rebuilt again with wiseco pistons and Halfpipe.

the WaTeRhAwK

you need to check the flywheel and woodruf key. I had one act like that with a sheared key.
when the flywheel key shears, and the flywheel nut is tight enough to keep the flywheel somewhat fastened to the shaft, the flywheel will spin in and out of time, causing it to backfire. one timed setting will cause it to backfire though the carb, another setting will cause it to backfire through the exhaust. if the key is sheared, it will backfire which ever way the timing happens to be at the time.


the brain in that msd system could also be causing it to fire out of time.

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CCC