Dong Fang DF 250 RTB Bobber Information

[DanDaMan]

I have a feeling the stalling bike has the size 86 main jet , FAR to small , causing it to over lean (fuel starvation) at speed , which if not corrected causes overheating and eventually valve burn

untill u get bigger main jet I think you need to RESTRICT (tape up) your intake not get a more free flowing one , take a 6" piece of duct tape rap it around your air filter only leaving it about 1/4 open , go for a ride if problem goes away thats the problem u need bigger jets (because your getting to much air in the air/fuel mix)


^^^^ messing with fuel mix screw could help also , If I recall screwing IN in richer and out is leaner , so try 1/2 a turn at a wack
PS - pay attention to how much you turn the screw so can get it set back to where it was originally (if needed) , by counting 1/2 turns made , write it down if need to



even with my big 111 main jet at 75-80 indicated the motor will occassionally cut out from fuel starvation but never bad enough I need to pull over


I went to auto parts store and bought a radiator hose (used the air filter for sizing) with a 180 degree bend in it cut it to only have the U shape bolted it to the carb the other end to the air filter , now I have a forward facing air intake out in the air stream - aka poormans air ram ( no real effect untill past 60 indicated )


its a fine line we ride on these small bikes , LEAN produces more horsepower thus more top speed , but to lean and you might as well toss a grenade into the motor