Help with valve adjustment ('02crf450)

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Aug 23, 2007
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#1
Hey guys,
I did a piston replacement but did not check the valve adjustment after. It has progressivly been harder and harder to start. After further research I have been told my starting problem is vave adjustment. Last night I popped off the valve cover to measure the valves. The exhaust valves are correct but the intake valves are so tight I could not get the very smallest feeler gauge in it.
Any suggestions would be greatly appreciated.
CLIFF :bang:
 
Joined
Jan 27, 2000
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#2
You should have .006" clearance on your intake valves and .011" on the exhaust, with .014" on the decomp lever.

If you have 0" clearance you will have to use the smallest shim and measure from there.

If the head has a lot of time on it, it would be a good idea to remove it and inspect the valves and seats. Replacing the stock valves with the Kibblewhite stainless steel valves is a good idea and they will last a long time if you keep your valves adjusted. Be sure to use the Kibblewhite spring kit.

The '02 engine should have the exhaust valve rocker arm replaced and the cam chain adjuster upgraded if it has never been done. Check the ex rocker roller for wear or scoring. A new cam chain is a good idea on an older engine. Also, check your cam for wear. If the valves have been running tight for very long there may be wear on the cam.

Probably not the answers you wanted to hear but, there ya go. :cool:
 
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#3
Someone else suggested that I start with 5thousands smaller shims, reasemble it, remeasure than determine what size shims to finish with. When I did the piston I inspected the cam etc. For some odd reason I did not recheck or check the valve adjustment why I had it apart...duh.
Cliff
 
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#4
cnb4mx said:
Someone else suggested that I start with 5thousands smaller shims, reasemble it, remeasure than determine what size shims to finish with
Cliff

Cliff.

If you have the shim kit you can do that. It will take more time because you may have to do it more than once to determine the correct size. If you don't have the shim kit and have to run to your dealer every time you need a different shim then just use the thinnest shim and go up from there.

Also, if your valve adjustment has moved that far, there is a good chance your valve or valve seat is going bad and should be visually inspected. If you lose the head of one of your valves it will do serious damage to your engine and your brand new piston. :whoa:
 
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#5
It was suggested that I put some shims in around 5 thousanths less reasemble, remeasure and than do the math to determine what shims to buy. Everything checked out pretty good when I did the piston. I have no good reason why I didn't check the valve adjustment at that time. I have about 8 hours on the new piston. Thanks for your advise I'll let you know how it goes.
Cliff
 
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#6
cnb4mx said:
It was suggested that I put some shims in around 5 thousanths less reasemble, remeasure and than do the math to determine what shims to buy.
Cliff
Cliff.

Like I said, that will work but since you are already at least .006" too tight, you may want to go to a .010" shim to start with. If your head has never been rebuilt, it would be a good time to check it. A hour meter is a good addition to your bike. It is very important to record the time on your engine parts and replace them at regular intervals. Especially the valves.