Exhaust cam shim size

21 replies to this topic
  • mangler

Posted November 01, 2005 - 11:56 AM


Hello all.

I have a auto decomp cam for my 02 yz 426, I'll be doing the install probably next week sometime, but in advance I wanted to buy a shim refill kit so im not running around ordering stuff during the install etc etc .. does anyone know what i'll expect for sizes needed?

I was looking at

All Makes/Models Part Number: HCSHIM09
Refil Shim Package 9.48mm OD x 1.80-2.05mm
Refil pack includes 5 shims in each size in .05 increments.

Is this what I would need?

Thanks in advace!

  • grayracer513

Posted November 01, 2005 - 12:36 PM


The trouble is at this point that you don't know what shim sizes you currently have (or do you?) and the bikes are typically built new with shims in the 175-185 range. So, the kits start and end right at a point where you pretty much need to buy the one you listed, and the next smaller size as well.

  • mangler

Posted November 01, 2005 - 12:54 PM


Thanks for the reply.

No i don't know the size in there, this bike is like new (very little time on it) so im pretty sure there has never been a valve job done on it before.

I was just hoping to get the refil kit and not end up buying the entire shim kit.

But i guess I might have to get the full kit.


  • Pincushion

Posted November 01, 2005 - 01:42 PM


I bought that same kit (1.80 - 2.05) when doing my cam mod and it happened to work fine for me. As GR said though, its no guarantee. BUT... at the cost of the kit compared to what a dealer charges per shim ($5 around here) its worth it to have around.

I ended up with 195's on the exhaust side and measure within spec, but towards the tight side.

  • grayracer513

Posted November 01, 2005 - 03:00 PM


Buying two refill kits costs almost the same as the full kit, but there are shims in the full kit that you will absolutely never use, and there are more of each size in the refills.

As for having the right ones readily available, did you know that the shims for a CRF450 fit your bike? Since they do valve adjusts more frequently, that expands the likely availability of your size by a considerable amount, and your bike really won't know the difference if you don't tell it.

  • 642MX

Posted November 01, 2005 - 05:16 PM


My local Yamaha dealer doesn't charge for shims, they will trade you for what you need.

  • 426_Texan

Posted November 02, 2005 - 04:02 AM


Buy a mic, measure the lobes of your current cam.
Meause the lobes of the new came.

Measure your current shims and replace with the thickness you need...

  • mangler

Posted November 27, 2005 - 05:11 PM


Finally just today got to get this installed with the help of KEVXR416 , well actually he did all the work. I just supplied the beer and moral support. :applause:

Had the stock .185s

I did end up with the .195 shims. This cam is the shiztnat!! :ride:

Odd kicking this bike and not having to worry about decompression. Too bad the weather is crap in the Midwest now.

  • mightymouse291

Posted November 27, 2005 - 06:32 PM


Hey Grayracer---I am waiting for my 450 cam to come in for my 426 mod. I checked the clearances on my stock cams, just for experience. Can I use my measurements for the exhaust side, and go ahead and purchase shims for the new cam or wait? I kinda want to have all the parts there to do it all at once If I Can??

As always thanks for sharing your knowledge.....

  • mangler

Posted November 27, 2005 - 07:02 PM


If the shims are stock, they should be the 185's. pretty simple the cams lobes i think are .10mm difference from the stock cam. the 195s should work for you also.

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  • Pincushion

Posted November 28, 2005 - 08:10 AM


Wait until you get the cam. 185 was not the standard size from the factory as mine had a 178 shim. They shimmed each motor from the factory independently depending on what it needed.

Glad to hear you got it installed mangler. I've been really enjoying my cammed 426 also.

  • mangler

Posted November 28, 2005 - 09:32 AM


Yes thats good advice. I didn't know that the can be different. I got lucky and my buddy had a hotcam shim kit for his 450X and had the sizes i needed. They are exactly the same.

It is awesome being able to just sit on the bike and kick start it, and not needing to worry about the decomp routine. To bad the weather is been so crappy now here in the midwest, I'd love to go "wring" it out.

  • Pincushion

Posted November 28, 2005 - 12:19 PM


Trust me.... you'll like it. I did the cam mod when I rebuilt my motor and added the 444cc jug/piston. I also put on the FMF PB and Q silencer at the same time, so it was a night and day difference for me. That damn bike makes such linear power now that's its deceptive. It pulls 5th gear as hard as it used to pull fourth, but its so damn smooth it feels slower.

Whats the weather like in IL?
I lived in McHenry county for about 16 years.

  • mangler

Posted November 28, 2005 - 04:57 PM


Well its been wet and cold etc etc.

Thats where i live McHenry Co. Town near crystal lake... Know it?

  • Pincushion

Posted November 28, 2005 - 05:05 PM


Well its been wet and cold etc etc.

Thats where i live McHenry Co. Town near crystal lake... Know it?

LOL... I used to live in Crystal Lake until 1998. On Country Club Dr. near Meridian right by the golf course. My father owned land on Queene Anne Rd in Woodstock where I had a track. Ever ride down in Otowwa? Is that place still open.

Sorry to threadjack.

  • mangler

Posted November 28, 2005 - 06:36 PM


haha cool, im in Cary right next door! :applause:

Yes that is where we ride. Ottawa, Bufflo Range and Fox Valley. Yes they are still open :ride:

No worries about the thread, it was done just wanted to finish off with my last comments for anyone later on needing the same info.

Rock on!

  • nussages

Posted November 28, 2005 - 06:58 PM


I recently adjusted the valves on my 04 yz 450. Shims are only available in increments of .05mm . This was not accurate enough in my opinion, so I used 360 grit wet/dry sandpaper and wet sanded my existing shims to the very center of the specs. It worked great! The feeler Gage measurement was dead nuts once the cams were reinstalled. I was thinking you could either use some shims you already have or get some thick shim kits and save a trip to the bike shop if need be. Anyway, it may sound shade tree, but I will never do it any other way personally. Its the only way I know of to keep you off the border line of being too loose or tight. If you decide to do it, you will need to lay your paper on a very firm, flat surface (obviously) and rotate the shim often under your finger to keep it square. Make sure you also check for thickness variation after you are done sanding. Good luck with your new cam!

  • 426n520

Posted November 30, 2005 - 06:34 PM


I have a 2000 426 and was thinking about the mod cam. Is it the same one as the 02?

Was it worth it for performance and starting?

  • mightymouse291

Posted November 30, 2005 - 08:05 PM


Just finished my cam mod on my 01 426..WELL WORTH IT

  • mangler

Posted November 30, 2005 - 09:14 PM


Im not sure about the year difference, i'll bet its the same.. let some of our resident experts answer that.

But the difference in the bikes starting is just amazing, you can actually sit and just kick it to fire it up. So easy...almost kicks over as easy as my sons crf50.

I havent gotten to ride mine yet due to our crappy weather. But its a cheap mod thats pretty simple to do, and just the kick start ease is well worth it to me.

Good luck!

I have a 2000 426 and was thinking about the mod cam. Is it the same one as the 02?

Was it worth it for performance and starting?

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