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2005 yz 250 not starting

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Ok, so I need some help here. I just finished putting my 2005 yz 250 (2 stroke) back together after replacing the top end (piston/rings/seals/gaskets) And now I am unable to get the bike to start. On the first kick through it will almost start (seems to get a half spark) and then nothing after that. After kicking it through multiple times I checked the spark plug and found it covered in coolant and there was also coolant sitting on top of the piston. There is no coolant in the oil and I have great compression and spark (but I think the coolant is drowning out the spark), cleaned out the carb to make sure gas is getting through. 

 

   Any thoughts to what the problem could be? (bad head gasket, crack in cylinder, etc) I would like to get an idea of what to look for before I take everything back apart 

 

   Thanks guys! 

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Ok, so I need some help here. I just finished putting my 2005 yz 250 (2 stroke) back together after replacing the top end (piston/rings/seals/gaskets) And now I am unable to get the bike to start. On the first kick through it will almost start (seems to get a half spark) and then nothing after that. After kicking it through multiple times I checked the spark plug and found it covered in coolant and there was also coolant sitting on top of the piston. There is no coolant in the oil and I have great compression and spark (but I think the coolant is drowning out the spark), cleaned out the carb to make sure gas is getting through.

Any thoughts to what the problem could be? (bad head gasket, crack in cylinder, etc) I would like to get an idea of what to look for before I take everything back apart

Thanks guys!

Maybe the new gasket is not seated correctly? Or it's damaged? Not sure what type of gasket that bike has, some have massive O Rings and others are all different..

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Check the o-rings on the top of the cylinder. Either one of those is broken/not seated, or the base gasket is leaking.

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Check the o-rings on the top of the cylinder. Either one of those is broken/not seated, or the base gasket is leaking.

Ah so it is a oring. Only the inner one will matter, the outer one will make it spew fluid out the top of the head but not into the cylinder. Be sure to check that, leaving it in wrong will ruin it so fix if fast if that's the issue.

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