Huge Backfire???

[warriorrider18]

Im workin on my buddys warrior and it just cranks and cranks and after about a minute it sounds like somebody shoots a shotgun next to your ear it backfires so loud but it wont start it has fuel spark and compression but i have never heard something back fire this loud. Any ideas?

 

[warriorrider01]

timing must be way off

 

[MotoArts]

It's the unburned fuel that collects in the pipe from the cranking, catching a spark and lighting off.

Probably a timing issue as 01 said. Does it have good compression (bent valve)? Plugged pilot jet or accelerator pump circuit in the carb? Bad spark plug, wire, cap or coil?

 

[warriorrider18]

it has good compression and we cleaned the carb so i know the carb is clean but i didnt even check the timing, could it also be the intake valve not opening

 

[warriorrider01]

when an engine is out of time, that is 'basically" what it is...the timing of when the valves open and close is probably off and the valves are not synced together...i dunno how to really explain it.

 

[warriorrider18]

alright i will try the timing

 

[warriorrider18]

its not the timing we set it and it still backfired

 

[1998yamahawarrior]

Out of curiosity ohm the stator. I had a bad stator that would have a good spark occasionally and I would get a backfire. Might as well check all bases, sometimes its the not so obvious things that end up being wrong. Ive even had a bad ground cause similar symptoms.

 

[warriorrider01]

assuming you had it at TDC?

 

[warriorrider18]

found the problum the intake valve is sticking open