Jet Moto 125cc won't run well

Just bought a jet moto 125cc, its an 06' all stock motor and bike. Has roughly 20 hours on it. Guy ran it last fall and said it ran great, but I went to pick it up today and ran like crap. Wouldn't idle, barely ran and a ton of popping on the decel side. Compression is at 185psi.

Had a cheap KN filter on it and quick put a foamy filter on it and ran better. Sounds like the motor is not getting enough fuel but I know the guy never changed jets or anything.

I'm gonna try putting new gas in it and adjust the valves to .003 on intake and exhaust. What kind of spark plug should I be using? What is the stock fuel screw settings? what is the stock pilot jet? and what is the stock main jet?

Did I buy a bunk pit bike or am I missing something? Bike looks brand new no scuffs or wear anywhere.

Thanks for any help

What kind of motor/carb is in it?

124cc jet moto with a mikuni 26mm I think, I'll have to look tonight. Called Jet moto yesterday and they told me to adjust the valves at .004 on intake and .006 on exhaust. What kind of plug should be in there, NGK C7HSA? right now there is a champion.

Got it to idle and run pretty good this morning, guy had the idle screw all messed up. Gonna buy a new plug and put fresh gas in it, pick up a nice uni air filter, change the oil, and check the valves.

Oil type, Jet moto said I could run synthetic as long as it is wet clutch compatible, is this true?

i have some klotz MX4 left over can I use this or should I run petrolium based oil?

I run valves at .003 intake, .004/.005 exhaust. I use non synthetic oil (Honda gn4) If ya can, get some pics of the carb.....maybe someone will know what it is for sure, and possibly even can tell what jetting to use. C7HSA plug sounds right.

thanks for the help, I will grab a pic of the carb and motor tonight.

Question - for buying after market graphics and plastics, shocks, etc. Is it safe to say that it is a CRF50. Thats what this bike was copied from. plastics and everything look exactly like the CRF50

yea plastics and everything should fit fine if you say its a crf50, mine was a crf50 copy basically too from chinese people lol and the plastics fit fine here is a pic.....also when u guys ajust the valves to .003 etc where are those valves and how do u do it lol???


The motor is a jet moto and the carb is a mukini 26mm. I cleaned the carb last night and the pilot jet was completely plugged. Seems to run a lot better. thanks for the reply about the plastics.

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