2006 Yamaha YZ 250f top end rebuild

I got the head back from Reeves racing engines and I would have to say that he did an excellent job of cutting the valve seats and installing the new valves.  I highly recommend him and his pricing is very reasonable.  His number is listed in an older post if anyone is interested in having him do some work for you.

Here is the head assembled and ready to be installed:

Installing the head on the cylinder and re-shimmed the valve lash:

Then install cams, chain, tensioner and cap:

After all that, Its time to test it out:

So far, the top end of the bike is great.  No strange noises or vibrations. However, I do have a problem in the carburetor.  It bogs if you snap the throttle coming off an idle.  Apparently, this is a common problem on the stock Yamaha 250f’s and what I have read is that it typically is a problem with the leak jet being too large and letting fuel leak into the bowl instead of being shot into the intake from the accelerator pump.

I’m going to pick the new jet now and installing tonight.  I’ll update soon.

Author: joedean

Share This Post On