Yamaha 50 Dirt Bike

Quadrider10

Member
Dec 18, 2011
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So im fixing this dirt bike for a customer. he said it wasn't starting. i took it all apart, cleaned carb, got it all back together, and it started rite up. however, it wont rev. it idles perfectly but as soon as i touch the gas, it bogs out unless i rev it slowly. it revs slowly though. in firt gear it run fine, but as soon as i hit second gear, it bogs no matter what. but again, it idles perfect. it got brand new gas, strong spark and a clean air filter. if i lean the air screw, it help with the bog when i first touch the throttle, but it way too lean. Any Ideas? its a 4 poke BTW.
 
Ok so I cleaned it out as best I could. However, now it's not bogging much, but it's running poorly. Like its way lean. I took the air box off and filter and tried like that and it was bogging even more which seems to me to be running lean. Ideas?
 
Everything is bone stock. The only thing changed was the air screw and that was by me. Its pretty far in. I don't think it's leaking. I can check however. If I'm not mistaken, an air leak or a lean mixture on a 4 stroke isn't bad rite? And yes it's a ttr50
 
i had a ttr90 and the carb was wicked hard to get to the air screw,they pit it on inside closest to the motor, and when i bought it that was one of the problems,plus stale gas and dirty carb :)
Did you check plug gap?
i bought a kids quad and the friggin thing was almost touching :(
 
Is the air filter damaged and lettin in excess air?

Could you have overlooked some crud in a jet?

A lean mix or an air leak is bad for any engine, it creates excessive heat.
 
i had same problem with the ttr90 ran great with choke on and not with it off,it was def a carb related problem,and i fiddled with carb for pointless hours i was able to fix problem lol...some people just replaced the whole carb to solve there issue but i did not o_O