Valve shims not seating?

I almost had my valve clearances set but have run into a snag. The last two do not want to seat properly. In both cases I've gone down by .005mm from the previous shims and the new clearance measurement is equal to the old in one case and even less in the other. I popped them down in their buckets and they appear to be seated but I have to assume they're just not quite there.

I will confess that these are not new shims but exchanged. It is also likely that not all of them are Yamaha. I did, however, measure them all with a digital micrometer/caliper and they were all either right on the money or within .001mm. Amazing.

I suspect that someone will just tell me to buy new shims and I realize that might take care of it. Still, I've got three questions:

1) Are non-Yamaha shims possibly a slightly different size or shaped just a bit different?

2) I have rotated the cam lobes over them a few times to see if they'll snap or press down a bit. Should I expect them to seat down at all when the engine is started? (If so, what good are any of the measurements I took?)

3) I'm not sure how anything could have gotten underneath them but is that possible?

Sorry to be such a pest. I sure do appreciate all of the help people have offered, though. Thanks.

 

Suzuki shims are also 29mm diameter, but they have a "bevelled edge" rather than the correct (for Yamaha) perpendicular edge, and that is what causes them to not fit into the Yamaha buckets.......

 

Measure the outside diameter of the shim, our Yamaha's use a 29mm shim. Some older Kawasaki and Suzuki use a 29.5mm shim. I have had the same problem, the vendor had mixed them up and shipped me the 29.5 shims. They won't fit.

 

maybe your original measurement was off?

maybe you have a situation where new shim A was supposed to go in bucket A and new shim B was supposed to go in bucket B, but you accidentally put shim A in bucket B and shim B in bucket A?

and chacal - wouldn't a bevelled edge, if anything, cause the shim to sit lower in the bucket and create a larger clearance?*


*not that i advocate using suzuki shims in a yamaha bike.

however - on a related note - i recently read that my Kawasaki KLR650 can use the same shims as my Seca 750 - anyone know if this is actually true?

 

I would only use Yamaha shims, not bothered if they are new or recycled though.
Shims must fit down into the bucket & measure in spec', if this isn't the case DON"T even turn the motor over, let alone try to start it.

 

BAYTONEMUS,

I noticed the same thing when I was checking/changing my valves. i posted a similar question. i felt like i had to take new measurements and adjust accordingly. this meant that i usually had to change the shim at least twice per valve to get the right number. kind of a pain, but i finished with everything in spec and my bikes runs very well. i did mine over a bit of time, but didn't notice any of the shims seating any lower. hopefully that helps. all of this is assuming that you are using the right shims, which it sounds like you are.

 

It's true. Both use a 29mm shim. You can get shims for your KLR from Chacal (But don't tell him it's going in a Kaw, he only sells parts for XJs :wink: )

 

thats why you should use a degree wheel to set the clearance, that perpendicular to shim just ain't close enough
the chances of you rotating that engine to the right spot eight times without a degree wheel are pretty slim

 

Try cleaning up the sides of the shims. (use very fine sand paper)

 

Thanks for all replies.

Out of curiosity, can you see that bevel when examining a shim or is it more subtle that that?

I'll check this out later. Seems like I wouldn't have been able to get these down in the bucket at all and they're not that far off from where they should be. A possibility, though.

Not impossible, but I don't think so. I was pretty careful.

How can this be? You have to turn the motor over when valves are out of spec or you couldn't replace the shims. Half of my valves measured 0 clearance (or at least less that .002 inches). Also, they do "snap" down in in many cases even if you've got them pressed into the bucket, right? Maybe I'm not understanding what you are saying.

THANKS AGAIN!

 

Seriously? I assumed that there was at least a range of several degrees where the radius of bottom of the cam would be consistent. Not so?

 

Chacal wrote in another thread somewhere that the "hardening" of the shims only extends a few microns below the surface. If this is the case, wouldn't you run the risk of removing that material, at least along the edge? I suppose the test would be whether or not that practice has actually caused problems for anyone who has been doing it over a long period of time.

 

Hi Polock,
I don't think my standard cam wheel will work on the xj. Do you know of a company that makes them with the square hole in the center? Or am I way off in my thinking.

Thanks
James

 

My 2 cents:

When I was swapping/checking shims I noticed the the oil I used when re-assemblnig the cams/caps was pooling under the shims when I went to re-install them.

Assuming the valve shim is seated properly and not cockeyed, try rotating things untill the valve is fully open and leave it there for a couple minutes to let the pressure squeeze out any excess oil trapped under the shim. Then re-measure. Worst case scenario you're out a couple minutes.

 

i think i still have the file at home, i just printed it and taped it on the wheel
i think four quadrants is all thats needed

 

baytonemus, I said don't turn the motor over if the shim isn't seated in the bucket, you'll break something, I was trying to help you, not being smart.

 

No problem, wizard, I didn't take it that way. I'm just trying to learn how to do things I've never done before. Also, tone (and humor) are sometimes difficult to convey in email or on forums, (especially when you hate emoticons as much as I do). I genuinely appreciate your response.

However, now that you've clarified what you meant, I am concerned because I turned the engine over (by hand) many times with one or more of the shims removed. I did quite a bit of studying of threads cover the procedure on this forum before starting and I don't recall having ever seen that mentioned. I don't doubt that it was somewhere, but not in what I read.

So what have I ruined?

 

Turning the mill over (by hand) with 1 or 2 shims removed won't do any harm, it was if the shim was half in the bucket & under pressure from the cam.

 

Well, I just completed the valve clearance adjustment and here's what I found. I took the two offending shims back where I got them and exchanged them (again), but this time made sure that I was getting Yamaha shims. The crazy thing is that ALL of the shims measured 29mm or even just a hair less in one case.

For what ever reason, it appears that the Yamaha shim just fit down in there a little better on one valve. Maybe either the bucket or the shim where not quite perfectly round??? Who knows...

The other valve was a different issue. Apparently that cam is a little misshapen. I had not previously thought of checking the clearance in positions where the lobe was not at 180° away from the shim. When I put the Yamaha shim in and it still didn't measure correctly, I decided to rotate the lobe a little bit of off center and, at one point only, a thicker feeler could be inserted. Might have been as much as 15% or even 20% off.

I have no idea if this could cause other problems but it seems as though the main thing is that, during some point in the travel of the cam lobe, the clearance will allow proper operation of that valve, right?

 

PHEW! That's a relief. Thanks so much for setting my mind at ease.