400ex rebuild problems!

[hondaracer44]

Hey everyone I just rebuild my bike with a wiseco 11:1 high compression piston and it has a stage 2 cam. I was riding it and shut it off then when I started it again it backfired and now won't start. If you pump the gas it'll fire and run as long as you keep pumping the gas but it won't stay running can anyone help with this?

[DragonGunner]

Hey everyone I just rebuild my bike with a wiseco 11:1 high compression piston and it has a stage 2 cam. I was riding it and shut it off then when I started it again it backfired and now won't start. If you pump the gas it'll fire and run as long as you keep pumping the gas but it won't stay running can anyone help with this?


Could be a stuck choke, or your choke is on…when that happens you usually have to keep up on the throttle to keep it running….however a backfire and hard starting could be a lean condition. Check choke, if not that I would tear into the carb completely using carb cleaner, total overhaul.

[honda400ex2003]

what size piston and what jets are in your carb? although it is odd that it ran decent then started acting up, it is worth asking those two questions.

after that, check for good spark, check timing (that is a very possible option, that it jumped time or the valves are out of adjustment after breaking in the cam a little.)

check gas flow, inspect jets and clean carb well during inspection of choke and throttle linkage

a few things to check out before you get too crazy with it, may be a little late though as it has been 2 weeks already.

steve

[DragonGunner]

Since he never came back I'm guessing he found out his choke was still on….seen it so many times from guys who forgot they left it on.