vfr400 nc21 motor backfiring

[driftkart]

My VFR400 powered go kart has just started to back fire abit when reving also when driving at the top of each gear. Seems to run wee rough.

Any idea's?

It is fuel pump feed also.

Thanks in advance

[Sable]

clean balance carbs check fuel pump exhaust tight, no leaks

[driftkart]

clean balance carbs check fuel pump exhaust tight, no leaks

Found slight crack in exhaust?

Ill drain carbs today