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.

 

Suzuki LT50s were designed about the same time, and the Linmax copy of LT50s used premix fuel, Linmax stated the ratio should be 32 to 1. If the oil pipe nipple in the manifold is open it will be bleeding air in, giving a weak mixture at idle, not so much at full throttle, plug it and check the air/fuel ratio afterwards. Most two stroke tiddlers seem to have a pale grey plug nose. May be worth checking the plug colour after a fairly long run to see if your air/fuel mixture is correct.

 

Got the stock carb cleaned thoroughly and a new pod filter put on it, now it will idle for a few seconds then stall. Choke lever has a lot of slop in it, how do you get the proper adjustment? Can’t tell if it’s seating all the way / staying open. Needed to have this thing done weeks ago and it’s still giving me trouble.

 

You can't really tell when the plunger is seated, just that if it isn't sticking in the carb, the spring should push it right down. There should be a bit of free cable when it is down, to ensure the cable isn't stopping it from doing so. If the idle speed is right but it stalls, you may have to adjust the slow running mixture adjuster. I don't like doing this as they shouldn't need it unless someone has been messing with it. Make sure you know where it is now (how many turns out) then slowly screw out, if revs fall, try screwing in, revs should rise one way or t'other, then start to fall again, screw back until revs are at their max. I tend to err slightly rich, or you can get a stutter when you accelerate.