Need help with a crf 250r 2005

[adrenlinerush008]

I have a 2005 crf 250r that will not start. The engine had locked up, and I was told I had to replace the bottom end. So we switched it out completely but it still will not start. There is compression, fire from the spark plug, and the timing is dead on. I can't think of anything else that could be wrong.. Any ideas??

 

[RM85rider123]

are the valves adjusted correctly? Have you checked the carb? You should've started with the simple things first.

 

[adrenlinerush008]

I do need to check the valves but the carb is fine

 

[RM85rider123]

I do need to check the valves but the carb is fine

That could be your problem right there. If your valve clearances are out of spec, it is harder to start. Adjust your valves, and see if it works.

 

[_JOE_]

Did you replace the piston when you did the lower end?

Valve clearances need to be monitored closely on a 250f.

I would lean toward a clogged pilot jet or tight valves, but it's possible there could be bigger issues such as the cam gear spinning on the cam when the engine locked up.