Valve clearances

8 replies to this topic
  • AMS2015

Posted May 04, 2016 - 12:44 AM


The bike is a 2005 WR450F

Measured my valve clearances yesterday, the feeler gauges i have are. 0.1 ; 0.15 ; 0.20 , 0.25; 0.30 etc. 

Inlet valves .10 feeler went in, .15 did not. (Spec is between .10 - .15)

Exhaust valves .15 went in nicely .20 did not. (Spec is between .20-.25)

So this means I have to shim my exhaust valves. But before i can do this I probably need to get a more accurate set of feeler gauges in order to find out what size shims I need? 



  • Krannie McKranface

Posted May 04, 2016 - 04:50 AM



...and a set of cheap digital calipers, as the clearance must be measured as well as the shim

  • toten

Posted May 04, 2016 - 09:07 AM


A mic makes a little more sense than calipers when it comes to shims, but calipers can be adequate. You'll probably find more other uses for calipers than mic.

  • AMS2015

Posted May 04, 2016 - 12:42 PM


Alright. Thanks for the answers. I've ordered the tools, will wait for them and then continue. 

But I'll already do some research. When i know the exact clearance of the valves, I should continue and get to the shim, then measure it using the digital caliper and then buy a bigger/smaller shim from that? 

Should I shim all the valves together (make them perfect) or just the ones that are out of spec?

Edited by AMS2015, May 04, 2016 - 12:42 PM.

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  • toten

Posted May 04, 2016 - 12:47 PM


If you're planning on keeping it, a full set of shims is convenient to have and not that expensive. 


Shims are typically labeled but it's a good idea to measure in order to verify. Labels can wear off too. 


If you're pulling the cams I'd shim all of them. 

  • AMS2015

Posted May 18, 2016 - 12:43 PM


Alright, got my feeler gauges and a digital caliper. 

Went over the valves again and it turns out that both of the exhaust cams are 0.16. (Spec is 0.20 - 0.25) The shims inside were 1.82. So in order to get them in spec I need a shim thats....

target 0.23, difference 0.23-0.16=0.07, means i need 0.07 thinner shim which is 1.75 ? Am i correct in my thought process?

I also stumbled on a thread in a other forum

Does this mean my head is done soon?

  • RMK800

Posted May 18, 2016 - 05:35 PM


After shims are set on a new bike. Usually you can shim the valves twice more. Your pushing it if you do them three times. Atleast that is what I have read. Also you can buy shims in .25 increments.

If this is a five valve motor your center shim will wear out the fastest.

Edited by RMK800, May 18, 2016 - 05:37 PM.

  • AMS2015

Posted May 21, 2016 - 10:48 AM


I bought the bike used and dont know how many times it has been shimmed before.

Is there a certain shim size from the factory or its different for each individual engine?


  • nateb1583

Posted May 23, 2016 - 06:02 PM


When I originally checked my valve clearances I used a set of feeler gauges I picked up from Lowes. Got everything set in spec (or so I thought) but I was still having trouble getting my bike started. A while later I happened upon a picture of a set of Motion Pro feeler gauges when I was reading up on installing the hot cams exhaust cam and noticed how they were bent on the ends. I ended up taking a pair of channel locks and bending the ends of the whole set then installed the cam. When I checked clearances they were WAY off. I am not sure if this is just because the new cam was that much different or if I was getting bad readings from my feeler gauges but after putting it all back together with clearances in spec, the bike fired right up first kick and has been great since. Moral of the story (and maybe you already knew this?), if you are using a regular sleeve set of feeler gauges, I would recommend modifying them to reach under your cam's without dragging on everything else. I attached a picture of the motion pro for reference. 

Attached Thumbnails

  • feeler gauge.jpg


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