please help

[86250rrider]

my r is messing up. its on a new rebuild. its been shutting down as if fouling a plug. i have swapped cdi,coil,harness. the last time out it shut down,it kicked right over and started popping and backfiring like a car with a bad cam or jumped timing chain. it blew the pipe completely off the motor and got hung up on the flange!!!ok i tore it down: top of piston looks great,cylinder doesnt even look broke in yet,plug is perfect,head looks nice. the woodruff key is ok. could the stator seal be leaking fumes into the stator and the bike is igniting the fumes???? im lost on this. neil ported this and it rips !!!!!!! anyone ever see this happen. its freaking me out. it did this after the top end,the other thing i changed was this stator.there is a stator on the way for testing now. thanks for any help or suggestions:macho

[koh0001]

Will it start up now? will it stay running?? Could be the reeds. My bike just shut off a couple of years ago, like a wire came off. I changed everything elec. still did the same thing. I could get it to start with the choke on but that was it. Give it any gas and it would shut off. Checked my reeds and found one broken off. I hope this my help.

[86250rrider]

it will run fine just long enough to leave me stranded in the woods!!! yes...the reeds are fine.

[EXtreme-]

I had a bad stator that had the same symtoms. We swapped every other component but the stator, then was forced to try a new (used) one and she fired right up.


you exploded pipe reminds me of when we used to drive my buddies Pinto down the road, shut off the ignition and turn the key back on while in gear. The longer the pause, the bigger the bang...LOL.

[Aceman]

Is your fuel tank full?

Sounds like it could be a fuel delivery problem. A restriction in the fuel system is letting just enough fuel into the bowl that you can run it for awhile until the bowl runs dry. Then it slowly fills it back up just enough for it start and cause it to backfire from running lean because of the lack of fuel.

[86 Quad R]

check the fuel cap.... could be vapor locking.