Crf450 Won't Start

[tim778]

I bought crf450 head with kibblewhite springs valves etc..and shimmed all valve clearances to specs. timing in order.But im having trouble starting it.I never had trouble starting it with the other head unless it needed shimmed.Started it the first night after installing the head it would run but it would not idle good so I gave up.Tried again tonight no luck not even trying to start it will backfire every so often double checked valve clearance everything checked out fine.Any advice appreciated....

 

[Rich Rohrich]

It's very easy to put these engines together with the cam timing off a tooth, which would give the symptoms you are describing. There are two seperate marks for the cam and two for the crank. If they mixed up you'll be off a tooth on the cam timing. It's worth taking a very close look at the crank to cam relationship to make sure the cam timing is dead on.

 

[tim778]

I set my timing like I usually do and it worked the other times and I read another forum about the timing could be off a tooth tried it no luck either way I set it..Thanks

 

[oldrnyzr]

check to make sure the carb is still connected, seated well. Sometimes the collar works loose.