Shims marked "A"

Moving shims around (900 engine)...I noticed the "A" mark on some of them
Just curious if this is supposed to mean anything:huh: ?

I believe thise are the ones prone to shattering. Roy

thought the A was half size,, but I will need to go to the shop and measure mine to see

No difference.

RonKZ650 wrote:

No difference.

+1 I concur.

otakar wrote:

RonKZ650 wrote:

No difference.

+1 I concur.

I've measured both (within a size) and there is no difference.

I just pulled my shims out last night, I have a couple with the 'A' and one that has a 'Y' in front of the number. :huh:

Don't the shims that were prone to breaking have a dimple in them? The 'A' shims that I have don't have any dimples in them.

JakeB wrote:

I just pulled my shims out last night, I have a couple with the 'A' and one that has a 'Y' in front of the number. :huh:

Don't the shims that were prone to breaking have a dimple in them? The 'A' shims that I have don't have any dimples in them.

Y = Yamaha, but will work...Jeff Saunders also mentioned that Ford SHO shims are also 29mm.

As Roy says, I too have heard that dimpled shims were prone to shattering. And the lower shim in the above posted photo appears to have a dimple.

The FSMs don't seem to mention the dimple issue with either shims or tappets.

My understanding from the 1974 Chilton's Kawasaki 900Z1 manual is that the original tappets (aka buckets) with navel (aka dimple) in tappet/shim mating area (P#12032-004 used up to engine #Z1E-08979) sometimes caused shim fracture, and were replaced with new design tappet P#12032-005, with recommendation to replace all old style tappets and also replace shims used with the old style because the shim may have begun to fracture.

But Chilton doesn't mention dimpled shims. :S

Hoping someone will better clarify this dimple business. Meanwhile, I would avoid shim or bucket with dimple.

Good Luck!