motor stalling

[ducar_rebuild]

hi i have a air cooled prox 250 and every time i give it a good run it shoots out flames and back fires but thats when i back of the throttle. In the high revs its ok and then when i slow down the motor stalls. When cruising its fine. Ive cleaned carby, airbox,fuel lines,done valve clearences, change spark plug, re wired still does it but not so bad do you guys have any ideas what is wrong any help appreciated

 

[Cactus Jack]

Sounds like either the exhaust valve isn't sealing or the ignition is missing or firing erratically ... To check the ignition timing use a timing light ... an inductive pickup power timing light is the best ... Look into the light to see if there is a steady pulse ... if the light misses a beat then your ignition is also missing a beat too ...

 

[wogtaz ryder]

Check the float in the carby , i somehow put one upside down and did similair.