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kickstarter kicking back

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i just finished a bigbore kit on my buddies 2010 250. Does anyone know why she would kick back every now and then?

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Flywheel not clocked correctly? ECU not remapped richer for the larger displacement so it's lean popping? Cam timing off? Valve clearances too tight?

Edited by Eddie8v

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flywheel wasnt off, checked cam timing a bunch and i use a chop stick down the spark plug hole for a 3rd refrance, ecu was remapped by yoshi., reshimed valves but really didnt need it.

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Stick down the spark plug hole doesn't work well, you need to look at left-side flywheel has marks to ensure you're at TDC.

Edited by Eddie8v

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yeah thats primary way. I use the right mark on fly wheel. Is that correct? Dont forget its a crf250

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yeah thats primary way. I use the right mark on fly wheel. Is that correct? Dont forget its a crf250

2nd tick mark, so the one to the right is a way to look at it yes.

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This is a 450. Not sure it they look the same when you look at it from a lower angle but there's a gap in the cover and the flywheel lines need to be inbetween this gap ImageUploadedByThumper Talk1401851134.969097.jpg

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FYI you posted in the 450 part of the forum........

yes i'm aware of that.

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If you can email me the mapping file I can check to see if it's close. Or just post up the fuel and spark tables.

Edited by Eddie8v

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its my buddies bike and yoshi. Flashed the ecu. I will ask him if he can get that info.

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Flywheel not clocked correctly? ECU not remapped richer for the larger displacement so it's lean popping? Cam timing off? Valve clearances too tight?

the right exhuast valve was at .095. I shimmed it to .011 and the problem has gone away.

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0.095"? That has to be a typo? 0.0095"? If it was at 0.0095", re-shimming to 0.011" wouldn't make any difference in starting (or operability) UNLESS you happened to correct an incorrectly timed camshaft during the process...

the right exhuast valve was at .095. I shimmed it to .011 and the problem has gone away.

Edited by Eddie8v

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.0095 was the reading and I check it 3 different ways 10 times and it was spot on every time. The 2010 250 cam timing in my opinion is hard to screw up(not like the older 450's).

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.0095 was the reading and I check it 3 different ways 10 times and it was spot on every time. The 2010 250 cam timing in my opinion is hard to screw up(not like the older 450's).

Yes, but you had to remove the cam to re-shim the exhaust valve, so maybe you corrected the timing upon re-installation? 0.0095" is fine for exhaust clearance, so you "fixed" something else in the process... plug wire not on all the way, who knows. Edited by Eddie8v

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Yes, but you had to remove the cam to re-shim the exhaust valve, so maybe you corrected the timing upon re-installation? 0.0095" is fine for exhaust clearance, so you "fixed" something else in the process... plug wire not on all the way, who knows.

All good now

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