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Showing results for tags 'runaway'.
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i have an 03 yz250 that i just put a new top end on. it was dropped in the mud while running and the kid kicked it over 100x to try and start it and wore the rings flat. it starts and runs fine for about 20-30 seconds and then the idle starts to get higher and wont come back down, if you give it throttle it will die out. i just went through the whole carb, cleaned the reeds, unplugged the tps and im out of ideas at this point. if you give it some throttle it will rev and then hang but after about 10 seconds come down and surge and the process will repeat every time you give it some throttle. i have 100 octane mixed 32:1 for fuel. any ideas would be appreciated
Have a 2015 YZ125. After a rather bad crash I had to replace the subframe and air box. I put it all back together. Kicked for 5 minutes Wouldn't even come close to starting. Had been sitting for 6 weeks or so, so I checked and Got spark, got compression, got new plug(old one showed proper color, not lean), got gas supply to carb. Anyway I lay the bike on its left side for a highly technical excess fuel purge and first kick with fuel off and zero throttle, it starts but have runaway engine condition. Had to use kill switch to stop it before it blew up. I have been reading that it could be crank seals or another type of air leak. Not really buying that because why would it start right up after simply laying it on its side. New air box should be sound and sealed. Anyway I would think the air leak if it's that is after the carburetor. On the YZ there is only the reed valve after the carb. I'm thinking crud in the carb but on a dirt bike you would think that would be a more common condition. Anyway, looking for ideas here.