'03 450 Exhaust Shims

Hey guys,

Started my auto decomp mod today without my cam. It should be here Wednesday 29th. I have 2 questions.

1. Once I have the 450 cam and go to check for clearance to see what shims I will need, do I put the camshaft caps back on over the exhaust cam and without the chain on?

2. The clearance on the left side (break side) is .216 and has a 176 shim.

And on the right side it is .216 and has a 178 shim.

There has been several post that claim the '03 450 exhaust cam is .17mm smaller that the stock 426.

My question is this, can I add the .17mm to the .216mm to determine which shims I will need instead of waiting for the cam to get here and then ordering the shims.

If the clearances are in spec. and they are, couldn't I use the math and the chart on page 3-23 to order my shims now?

It looks to me if I did it this way I would order a 190 for the left side and a 195 for the right side (doing the rounding up method.)

Thanks for your input,


Instead of trying to guess, order a Hot Cams shim kit from the TT store. WELL worth the $, and you'll never have to worry about shims ever again, and believe me, you will need shims sooner or later. :cry:

Hey Tim, how's it goin?

I know it would be nice to own a shim set, but I just can't let go of the $$$ for something I may not need for quite sometime. I'm just trying to figure out what the big mystery is and why we would have to wait for the cam to get in before we order our shims. It seems to me that some simple math would produce the correct shim sizes if you have taken correct readings, know the size difference in the exhaust lobes, read the chart in the manual and stayed within spec :cry:.

I guess I'll find out why everyone has had to wait when mine gets in this Wednesday :cry:.

I did speak with the Service Mgr. at the local dealer this a.m. and he said to just bring my old shims in and he would swap me! That was cool!

I have documented almost all steps of this cam mod thus far and hope that the pics will be of help to others. There should be around 20-25 pics when I am finished. yamaha.dude said he is thinking of revising the pdf and may use them.

Once it's complete, I will turn them over to TT.


I guess it's a little harder than doing simple math to calculate what sized shims you'll need. Try your theory out and let us know if it works! If you own a fourstroke, and won't go back to the 2 stroke, the shim kit will work for Yamaha's or Honda's. You can't go wrong. . .


you are trying really hard to get me to but that shim kit :cry:.

Is it a FurryBalls brand :cry: :cry:?

I don't like to say never, but it's highly unlikley that I would go back to a 2 stroke. I love the power and torque that the 426 gives me :cry:!

I will let you know if my theory is correct or not. The only way I see that it can be wrong is if the lobe dimensions on the '03 450 exhaust cam are not .17mm smaller than the stock '01 426 cam.

I think :cry: I will go from a 178 to a 195 shim on the brake side and from a 176 to a 190 on the shift side.

I'll let you know,


That sounds like a big jump, but do keep us updated. By the way, did I ever tell you about the Hot Cams shim kit. . . :cry:


next you will have a bridge you're trying to sell me :cry:!

To install the YZ cam not the Hotcams it seems like I only had to go up like .05mm. You really have to measure it with the cam installed and torqued down, the chain will not have to be installed.


My cam will be here tomorrow and I will get the new clearances then. I am anxious to measure and see where they come in at.

The .05mm you are refering to, is that shim size or clearance increase?

I plan on giving a complete layout of how everything measured before and after the DCM. There may something in it that others can use in the future.


That is the difference in clearance, the 03 cam has a smaller diameter so therefore thicker shims will be needed. Dont forget to record exactly which shim and bucket go with each valve. It will make things much easier in the long run. I actually just swapped some of the shims from one valve to the other and got away with getting like 2 shims. You are getting the 03 cam not the Hotcams? Might be different for the Hotcams. :cry:

I did get everything recorded and marked. Since I have taken digital pics during this mod, I've took my time and will probably set the record for the longest amount of time spent to do the DCM :cry:. And I haven't even received my cam as of yet to install it :cry:!

I am using the '03 450 cam for this DCM. Everyone who has installed one has had nothing but good things to say about it. I just couldn't justify the other $$$$ for the Hotcam. I'm sure it's a good cam though, I can use the other $$$ to buy some new bars or something :cry:!


I really did order that Shim Kit today :cry:!

You're to good of a salesman. Do you have any swamp land for sale :cry: :cry:!


Good call! The old Jedi mind trick worked once again! All kidding aside, you will LOVE that kit once you get it. Just the peace of mind knowing you will never need to order a shim again is well worth it! I guess never say never, huh? :cry:

I let the service mgr at my local dealer talk me into using a 181 shim instead of the 185 on the left side because he did not have one. He said that I would be ok and it was "Better a little loose than a little tight." I got it all buttoned up, kicked it 4-5 times and varooooom :cry:! Several hours later, pulled the choke and one kick, varoooom :cry:! I noticed a little tick. It may have been there before or it could be the valve cap so I am going to tear it back down and install the 185. It's alot of work but needs to be done!


That tick was probably your loose valve clearance. Pro Circuit actually shims their valves on the tighter side when it comes to tolerances. . .

That's what I'm thinking. It's not very loud but I know it's there. If I would have put the 185 shim in and it ticked, it wouldn't bother me as much.

You know the old saying, if you have time to do it twice you had time to do it right the first time.

I could kick myself for listening to that Service Mgr. He isn't the one that's having to tear the bike back down.


It will probably tick anyway, even with the new shim. I always hear things after working on them. Nothing ever goes wrong later so it must be paranoia. You ought to see my reactions to my diesel powerstroke :cry: I swear the thing is breaking down every time I drive it and it still runs like a bat out of hell! I still cant figure out the noises in the diesel engine and why do the sounds change when I am changing nothing (such as throttle position). Weird :cry:

It will probably keep ticking, but at least I will know it isn't due to the wrong shim :cry:!


I will let you know if my theory is correct or not. The only way I see that it can be wrong is if the lobe dimensions on the '03 450 exhaust cam are not .17mm smaller than the stock '01 426 cam.

I think :cry: I will go from a 178 to a 195 shim on the brake side and from a 176 to a 190 on the shift side.

I'll let you know,



As we talked before, you know that I've done this same mod to my 01-426 and according to you "theary" I would have put the wrong shims in. I had to go 195 shift side and 205 on the other. However, do post on your findings :cry:

And keep up the good work. You'll love your New Bike :cry:


Right you are Boyd! I did wait for my cam to come in before I got my shims. The dealer told me he had them in stock. When I went back to get them, he said that he was looking in the wrong shim kit and did not have the shims I was wanting. He asked for my clearances and told me that the 189 and 181 would be just fine.

When my new shim kit gets in I will tear it back down and get the clearances right. Practice makes perfect :cry:!


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