Rebuild Question- Valve shims (?)

KaZoo, I did not lap the valves, therefore no actual valve measurements have changed. I tore the head apart (pulled the vavles and springs), and while it was apart, I cleaned the valves (decarboned them), replaced the valve oil seals, check the spring tensions, and ground the valve seats- then reassembled. So technically, the only thing that CHANGED was the oil seals. That is why I am just trying to figure out what the stock (or like) placement of these shims were, so they could go back into where they belong. Nothing on the cam has changed either.

Sorry if I have been unclear about anything!

if you ground the valve seats you need to reface the valves also.
when you ground the seats you moved the seating surface farther into the head even just a few thousands of an inch will change the valve setting on the top so you will need to reshim the valves.
I would also lap the valves in also just to make sure you have a good seat all the way around the valve and the seat

The way the valve seats get cut is to use three stones which cut at three different angles. Normally, dressing with the final stone is all that is required to clean up the seats. Once this is done, as has been noted, the valves/seats must be lapped in. You can go to an autoparts store and pick up some machinists dye. You paint this on the seat and drop the valve in. Don't rotate the valve. Pull the valve out and the dye will for a ring on the valve face giving you an indication of the surface to surface contact area. If you didn't lap, the dye will show gaps for sure. Once you have the valves lapped in, I once again suggest going to our website and looking at the valve clearances tech article because you have definitely decreased clearances by cutting/dressing the seats; especially since most folks who do this chore on a bike for the first time get a tad ham handed and take too much material... even if it was done very lightly with a light hand, material was removed. Once valve clearances decrease to a certain degree, the valves will hang open a tad... given some of your shims were on the thing side, it seems to me this is a possibility now. If the valves hang open, compression will drop as the combustion chamber isn't sealed. Good luck...

Hi Cuddies, welcome aboard. One word of warning: I see in one of your pics you have both cams in the head, although not torqued down - until the cams are timed (= cam chain installed correctly) DO NOT rotate either cam with the other cam still in the head or you´ll most likely bend a valve or two (exhaust and intake valves will hit each other). If you´re going to bench shim it, do it one cam at a time with the other cam removed. You´ll also want the head sitting on something so the valves can open freely, if the head is just sitting on a flat surface and you rotate the cam you´ll likely bend a valve too.

Post edited by: OnkelB, at: 2007/05/09 17:12

Thanks, happy to be here.

Before I had taken that picture, I had rest the cams in place (no specific setting, just layed them on top) just so that I could see how it looked. Those were sitting there with no meaning, I took them off ass soon as I took the picture.


For some reason, I have a distinct feeling that the timing is going to be a PITA when I get ready to put the head back on, but for right now, my main concern is getting the shims back into their original placing.

dont even worry about trying to get them back in the origonal spot, since you have the sizes note where you install them and check the clearances, you can then move them around until you get the proper clearance, you may need to order some new shims to get them right

BSKZ650 wrote:

dont even worry about trying to get them back in the origonal spot, since you have the sizes note where you install them and check the clearances, you can then move them around until you get the proper clearance, you may need to order some new shims to get them right

Alright, I will try that out.


But, (might sound stupid..), when you say check clearences, you mean....?

cuddies wrote:

. . . I ground the valve seats . . .- then reassembled. So technically, the only thing that CHANGED was the oil seals.!

From reading the other posts, I hope you realize what I am going to repeat here.

When you removed material from the valve seat, the place where the valve contacts it will have receeded ever so slightly; enough that whatever clearances were originally there have now been reduced. The valve stem will therefore be slightly higher, raising the shim bucket slightly as well.

Whether you were careful taking this puzzle apart or not is not the point at this juncture.

The task at hand is going to be placing the correct amount of clearance between the cam and shim; whatever that is.

cuddies wrote:

That is why I am just trying to figure out what the stock (or like) placement of these shims were, so they could go back into where they belong. Nothing on the cam has changed either.

Sorry if I have been unclear about anything!

Sorry if I have not been as clear as I needed to be.

cuddies wrote:

But, (might sound stupid..), when you say check clearences, you mean....?

Better to ask questions now, while you have it apart. I think you need to slow down and unspring the valves, so you can set the valve train correctly.
The valves need to be lapped in.

As a friend of mine said, "sorrow is born in the hasty heart."

A rush here here is sorrow down the road.

If you are careful, you aren't going to break anything, including the new seals.

You want this machine to run well, not just run. If you do this proceedure wrong, you may end up with a bike that doesn't run at all, and a lot of frustration.

Reread this post. I have added some additional information.

Kiwiz wrote:

I would assemble the head on the bench without the valve springs, installing the cams. Select cam followers that fit and move smoothly in the bores.

Replace them, then the cams.
The cam holdowns need to be torqued to correct specs.

Kiwiz wrote:

Select a shim for trial. Naturally when trying any shim the valve itself has to be pressed hard up against the seat with your fingers and the cam lobe 180 deg away from the shim.

The clearances you are unclear of, is the space between the bottom of the cam lobe and the top of the shim you are test fitting. There needs to be an amount as designated in a manual specification. These are solid lifter engines. There needs to be some daylight between the cam and valve when the valve is closed and the lobe is away from it.

Kiwiz wrote:

This is much quicker than working with the head on the bike and gets you in a position that when the head is fitted the engine should start.

Reassemble head with valve springs and place on bike. Once valves timed go over them once more checking that clearance are within spec.

Ok we have a guy here who is willing to learn, thats great!!
the clearance comes from a feeler gauge, its the amount of distance in between the bottom of the cam lobe, high side to the top, and the shim, this is needed to allow the valve to seal.
you will have to find you feel, you want it to slide easy but not loose.
the best thing is do them all the same,not to tight but not to tight.
I know you will get it right, it may take a few times , but you will get it

Well, I never did figure out how they go. I did use the link that was posted, but still couldn't figure it out. It seemed like when I would get 2 or 3 (of the 4 shims, each side), right, then there would be at least 1 wrong, so I would switch that one wrong shim, and they measure again, and they they would all be wrong. Honestly, I am comparing this shim job to a rocket science jigsaw puzzle.

Well, good news. I got the exhaust side all within spec today. All 4 on the exhaust where .06mm. If I read the posted article correctly, the spec for my bike is between .05 - .10 mm. Just need to get the intake done and it's ready to go back together.