Valve shims

[Predatorguy88]

I have recently needed to replace a valve on my Predator. I was looking at my lite pile of parts today and realized I don't have a valve shim, so I can't finish the assembly. What I would like to know, how do I know which shim to use (many different sizes)? What is the stock size? I have a shop manual, and I'll check in it again, but I don't think it said anything about it.

Any help would be appreciated, this thing's been off the trails for about 2 months now, after my already long list of maintenance in so short an amount of time.

[TampaBoy813]

well you are going to need one just to get the right measurment...after installing one you will use your feeler guage to the right spec...then you will know if you need to go up or down in size...to get the required shim/Spec..

[wolffie]

http://www.exriders.com/vbb/showthread.php?s=&threadid=252993


this should help;) . the stock intake i believe are around 150 and the exhaust 180ish.

if the valves are loose you will need a thicker shim. if they are tight you will need a smaller shim.

[wolffie]

also forgot to mention, a good shim kit for ya is on www.magicracing.com or any YFZ shim kit will work for you.

[440exnacsracer]

i wasnt aware that the yfz shims work,... but the crf/trx 450 shims also work

[Predatorguy88]

Ok, thanks fellas. What I need to know now is how will I know if the shims are too thin/thick? And what shim kits will work on the Pred, if there isn't one specifically for it. Thanks for your help.

[440exnacsracer]

to start off, i would not worry about the factory shim size, as a new valve means it should have been recut/lapped, so its almost guaranteed to be different than stock. heres a step by step...
take the valve cover off, but keep torqued, or retorque the bolts holding the cams in. get the motor at top dead center.then just use feeler gauges to check the gap. then figure how much you need to make up the difference in the gap by adding or subtracting. im not sure what the factory specs are, but i believe its like 6 intake, 8 exhaust...that would be .006 and .008 respectively, but dont quote me on that. then, instead of buying an entire shim kit, i would just go to a local shop and see if you can buy some off one of the mechanics. a honda shop will have the shims for the crfs/trx 450s that will work, yamaha will have the yzf 450 shims, and obviously polaris should have some shims as well. good luck, and remember to final check your clearances with the new shims before assymbly.
ben