Misfiring

[sick150]

Hi

I have pulled out my old 150cc engine and fitted a 250cc engine with electric start connected the same coulored wires from my old motor but not the one to electric starter motor started the bike and it run ok but was breaking down at high revs changed the cdi to a new one put on a new carby and is still breaking down spluttering and backfiring ???? next i think i will check the vavle cleaance could some know what the vavle clearance is on a Zongshen 250cc engine and other engine specs.

your help would be a great !!

 

[rossetti]

are you still running the coil off the 150?? i dont know if thats it but its always worth a try getting the right one

 

[sick150]

Hi Yes it is the same coil I have notice that the 250 has a breather that may of went into a air box but i am not running a airbox should I put a extension on the back of the carby before the air cleaner and connect the hose there.
I have put a new plug and check the timing is ok but it still backfiring but does not do it as bad when it is warmed up????

 

[Custom]

Are you running an IRK? if so it sounds like the pickup air gap is to wide. Or i could be a loose wire in the ignition

 

[sick150]

Hi

More info IRK????

 

[Custom]

inner rotor kit

 

[sus1]

make it rev free and goes like vtec

 

[liljohn_92]

do irks fit in them 250 motors?

 

[Custom]

I would imagine that they would be ones made to fit.
Could be carb tuning to

 

[rossetti]

hey man dont worry bout the breather going into the airbox. check the connections going onto the coil to and check if there loose and just crimp them with pliers if they are.