Hi, i bought an xr250r 2002 model. I rebuilt the engine and put in new exhaust valves. After i did this proper compression in the motor came back and it wasnt blowing smoke anymore. I took it for a 'run-in' ride, and noticed that the engine was quite noisy. I guessed it was the valves needing adjusting. I got numbers for the valve clearences which were: .004 of in inch for the exhaust valves and .005 of an inch for the air intake. Now i have done this the compression in the bike is enormous, it is barely possible to kick over, and the motor is very noisy, there is a loud ticking noise which im guessing is still the valves. Is all this normal considering i have just rebuilt the engine, put in new valves and hardly ridden (one 50km ride)? I would like to keep riding it to run it better to see if the motor loosens up, but im scared to ride it as it is. Any advice would be greatly appreciated.
Did you adjust your cam chain?
I think you should check the other end of the engine too. Remove the sump and make sure the big ends have no play. Then you are good to go. Replacing the big end shells in good time is easy but if left too long then the engine is a right off. Possible also a transmission bearing is dying which you can spot at the same time.
.004 is a bit tight for an exhaust valve? usually this is nearer 10 thou. It is better to have slightly larger clearances to the tappets/ valves than to be too tight and risk burning your valves. You do not mention the decompressor! I'm sure your bike should have a manual decompression lever if not an auto retard unit on the cam shaft to allow you to atleast crank the engine up to TDC on the compression stroke. I suspect that is where the noise problem is coming from, either that or you might be one tooth out on your cam shaft gear allowing the piston crown to kiss the valve when it is open...hence explaining the very hard to turn over!! but see my other comment too! What ever It is time to remove the inspection covers and re examine the whole set up. BTW the bike should be an UTTER PIG to kick over compression without a decompressor!! as it has a very high compresion ratio. expect to be standing up on the kick start if you are less than 160 lb (11 stone) 78 kg
