Yamaha Raptor 350 Backfire

[THREADLOCK]

I have a 2004 Yamaha Raptor 350 4 stroke ATV.
Carb is a Mikuni 38mm BSR
Running at idle the engine backfires through the carb
(into the airbox). Running at high RPM it sounds like it is still doing it,just not as noticeable.
I took the carb apart and cleaned it out.
Machine runs a little better, but still the same issue.
Any help would be appreciated.
Thanks.

 

[PE175]

I have a 2004 Yamaha Raptor 350 4 stroke ATV.
Carb is a Mikuni 38mm BSR
Running at idle the engine backfires through the carb
(into the airbox). Running at high RPM it sounds like it is still doing it,just not as noticeable.
I took the carb apart and cleaned it out.
Machine runs a little better, but still the same issue.
Any help would be appreciated.
Thanks.

Sounds like your timing is off a bit

 

[gearhead730]

: Are your valves out of adjustment?If their out of adjustment too tight valve could be slightly open letting it blow back into intake.Or valve seat or valve face is damaged and it will not seal. :ride: