'84 XJ1100 valve shim question

[lsb909]

Before I post in the parts forum...

I've recently had a valve job done on this sweet beast and as the mechanic couldn't locate an accurately sized shim, we went with the looser spec'd size in one cylinder which has resulted in an irritating clacking sound I'd love to kill. He said the size of shim needed is 1.75 but he went with 1.80 (I think) to default to the safe side of the spec. Anyway my question is, does this sizing sound remotely correct? Everything I've seen for sale in a 29mm shim is 2.00 to 3.10. Nothing smaller?
Am I even looking for the right size? Why can't I find these?

thanks for any help. This is my first post. Amazing forums!

[IanDMacDonald]

I believe the shim chart goes from 200 (2.00) to 320 (3.20) for all of my bikes using 29mm shims. Also, by skipping a puck size, you can take the clearance out of spec one way or the other.

[GLoweVA]

With the wider(more open) size spec then there'd be a little more noise than if it was close to the in spec (smaller).
Generally if your engine is quiet, then the shims/valve clearances are too tight. Therefore these engines generally are 'noisy'.

Hope that's as clear as mud.

[natemoen]

Yeah, that doesn't sound right.

Lots of places to buy shims. Kawasaki and BMW also use 29mm shims.

http://www.newmotorcycleparts.com/mo...lve_shims.html

http://www.sudco.com/29valveshims.html

http://www.bikebandit.com/k-l-valve-...ent-shims-29mm

http://www.procycledepot.com/29MM_VA...503-85274.html

[MPittma100]

Shims

As the saying goes, "hindsight is always 20-20". Machinist should have ground the valves to make the existing shims work. After getting the head back from him, no adjustment should have been necessary.

Many size shims, as has been mentioned, are available. One of them should "fix" your clacking. Also make sure that your noise is not from a leaking exhaust port gasket.

[D0wn5h1ft]

As the saying goes, "hindsight is always 20-20". Machinist should have ground the valves to make the existing shims work. After getting the head back from him, no adjustment should have been necessary.

Many size shims, as has been mentioned, are available. One of them should "fix" your clacking. Also make sure that your noise is not from a leaking exhaust port gasket.

Is it really ok to grind shims? Don't they have a protective hardened coating on them and are very VERY flat to avoid scoring your cams?

[jwhughes3]

No never grind shims. He said grind the valves.

[D0wn5h1ft]

No never grind shims. He said grind the valves.

Can't read, my bad.

[MPittma100]

Can't read, my bad.

The heads that I have had machined have all had the valves adjusted by the machinist when he performs the valve job.

When you grind the seats, the valves go further up in the head -only a few thousandths. Therefore, the machinist grinds the valve tip to obtain the exact valve adjustment per the Yamaha service manual. The valve tip grinding is done before the springs/keepers/retainers are assembled. And, Viola, no valve adjustment needed when you reinstall the head.

So when you take a head to the machinist, give him all of the parts to the head including - pucks, shims, camshafts, and caps.

[BA80]

When you grind the seats, the valves go further up in the head -only a few
thousandths. Therefore, the machinist grinds the valve tip

It's called "dressing" the stems. That's exactly correct Mike.

This needs to be done or you end up with what lsb909 is experiencing. With screw type valve adjustments it's not nearly as critical but with these shimmed valves it needs to be done. Either that or replace the valves and some of these valves are no longer available new.

[crazy steve]

There's a minimum distance on the valve stems, so you have to be careful when dressing the valve stem tips. Minimum is 4mm (.157") from the top of the valve keeper groove to the end of the stem. If you go under that, then the shim bucket can come into contact with the retainer rather than the valve stem tip, allowing the keeper to loosen, leading to catastrophic failure when you drop a valve down a cylinder. I had just this happen to a motor when the machinist cut the stems short, so this isn't BS...

This is the weak point in this motor; once the valve seats have worn enough that the valves have recessed too far into the head, you can no longer find shims thin enough to adjust the valves. Yamaha says to replace the head and valves; your other choices are custom shims, custom retainers, custom valves with shorter stems, or custom cams ground with a smaller base circle. The OEM seats are cast into the head and I don't think there's enough margin between them to make replacing the seats feasible.

Custom = $$$$

[lsb909]

Amazing!

Thanks to all for the excellent info. I'll take it from here and see if I can find the right shim at one of the dealers. And I'll take up the more technical info directly with the guy doing the actual maintenance here as I only know enough mechanical info to get myself into trouble.
Can't thank you all enough for the quick responses.
This is an amazing forum and I'm glad to have stumbled into it!

[MPittma100]

Shims

Thanks to all for the excellent info. I'll take it from here and see if I can find the right shim at one of the dealers. And I'll take up the more technical info directly with the guy doing the actual maintenance here as I only know enough mechanical info to get myself into trouble.
Can't thank you all enough for the quick responses.
This is an amazing forum and I'm glad to have stumbled into it!

If you end up needing shims, they are available from several places. One of which is Ebay for used ones.