Posts
401
Joined
2/17/2015
Location
Morehead City, NC, USA
Edited Date/Time
12/8/2015 11:07am
just got a whole new overhaul on my bikes motor. we just got done doing a build on this bike from the frame up. its a 2004 RM 250. the motor got a fresh bottom end, top end and new cylinder head, piston.. ect. i did all the heat cycles and ran the correct gas mixture ratio as required. took my bike out on the track and about 3 laps into riding it just shut off and died. we couldn't get it to start after that. we went through the bike and everything was fine. carb was clean, spark plug was fine. just can't figure this thing out!!!
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Have you pulled the exhaust pipe and looked at the piston through the exhaust port to see if it seized?
Does it have good compression? Like above 160 psi?
Paw Paw
Few other ideas.
Take the plug out and spray in some starting fluid (just a little) and see if you can get the bike to fire for a few pings.
Check the reeds, possible one broke and got sucked in the motor.
I am betting its the timing, since everything else seems ok
let us know how you make out
The bike ran like yours, then it wouldn't start. I found out the float valve was sticking inside the brass seat. It would travel 3/4 of the way just fine, but that final point where it shuts off fuel is where it would stick. Then it wouldn't open back up so you basically run the bike until the carb is drained.
I put the old brass seat in and everything is fine. So I would definitely check this. Just remove the floats and physically move the valve in and out of the seat to make sure it never gets sticky or bound up at any point. Thats my two cents.
I just learned something new. Thanks for posting, guys!
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