yz450(03) cam/wr426, will not start?

I just fitted an OEM yz 450 exhaust cam and JamesNow mod. It took a few kicks and ran for a minute then stopped. Many minutes of kicking with choke on and off also a bit of throttle (seemed like not enough fuel). It started then back fired frightfully and stopped. No further kicking. Pulled it apart and rechecked timing again, as per all info I have. No noises during hand turning and clearances as Yami book (0.23mm). Prior to cam I turned the air scew out to 1 3/4 and bike starts great.It has a staintune pipe and 2500kms. Is the a jetting or starting issue or have I done something wrong.


Did you set the exhaust cam in one tooth off from lined up. I know when I did mine the directions said to rotate it one tooth forward from the existing timing.

Where did you get your info from about the one tooth forward. I would like to compare notes. Do you have a thread I could read. Thanks

I pm'd you.

Thanks, it was the same info I used.

I double checked everything, all ok. Did some basics, guess what 1 hour old iridium plug had failed. Stuck in the old CR8 and bang 2nd kick, awesome :applause: .

Never forget to go back to basics :p , but incredible it failed during the first 30 seconds of new cam operation. You can not imagine what has been going thru my mind- bent valves, dented piston. :ride:

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