Working on a Yamaha 60cc 4 zinger (from the 80s I believe). It’s been sitting probably 15ish years, og carb was almost completely plugged with garbage so decided to just replace it and put the og jets in the new china carb. Machine will start with full choke and will only stay running at half choke but will bog with throttle. Will be run/bog with no choke in the run position if holding the throttle but barely revs/moves. Have also removed gas tank to to clean out any old trash that may have been in it, installed new inline filter (gets good flow), new ngk spark plug, checked reed valves and removed/cleaned/reinstalled the whole exhaust system. Trying to get it running good for a friends grandkids so any help would be appreciated

 

Check the exhaust isn't plugged and try it with the jets the Chinese carb came with. If that doesn't work, they can loose compression through the crankcase seals, so check they are not weeping oily fuel.

 

Got it running a lot better, runs without choke and Revs up a little bit but falls on its face and has no power.

 

Check compression, it could have been laid up because the bore was badly worn 15 years ago.

 

Has around 120psi, fresh plug, cleaned out exhaust, checked reeds, cleaned out the gas tank, fresh gas, new pod style air filter, and new carb. The oil pump isn’t used so not sure if I should cap off the inlet on the carb or if there is anything else that needs capped? And I assume my mix ratio could be too far off for what this thing likes to run.