help! rebuild went south

Brother-in-law just rebuilt his 250f and it ran good for about 5 hours...then it became hard to crank or kick through, and will not start...he is a pretty good mechanic. Anybody got any ideas before we tare it back down?

Thanks Bill

did you put oil in it? radiator fluid? check the simple stuff first...and since its a 250f you might wantto ask in that forum since they might be better equipped to handle this...

also he might have possibly gotten water in the cylinder, i'v heard it makes it next to impossible to kick your bike over if you do, but i'm not sure how that works

Sounds like a nut has backed off and is hitting the inside of the case or maybe

you didn't set-up enough clearance on the big end bearing (If you rebuilt the crankshaft) Hard to guess, could be a bunch of things....Just take it apart...

I would start with the clutch cover first..

Brother-in-law just rebuilt his 250f and it ran good for about 5 hours...then it became hard to crank or kick through, and will not start...he is a pretty good mechanic. Anybody got any ideas before we tare it back down?

Thanks Bill

I believe your problem is going to be in the valvetrain. If its gotten hard to turn over. pull the valve cover and check it out. First check your valve clearances. Then pull the cam caps off and look for scoring on the caps and cam journals. If all that checks out . try and take the cams out and while holding the chain up with your hand, see how easy it is to turn the engine over by hand. I have seen a few 250's that were not set up with the proper valve clearance do this. Good luck and post what you find!!!!

I would check to make sure that you havnt over tightened the cam caps, which is easy to do without a torque wrench if thats whats happened, other than that I am not sure.

You were right the cam caps were to tight and journels scored...what is the best way to fix this problem or is the head trash?

Send the head to Engine Dynamics. They have done many of these repairs.

What do you estimate the cost would be? ballpark

Sorry, no idea, but it's my understanding that it's far less than a new blank head ($600). Contact them and tell them what you have; a YZF that needs the cam bores line bored.

thanks gray will pass it on to brother-in-law.

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