Question about valve clearance...

[brs127s]

I have measured all of my valves and will try to get the shims I need tonight, but I have a general question. If you have a valve that it at say .003mm, would it be better to change the shim so that your clearance is a .008mm? I guess what the question boils down to, is it better to have tighter tolerances for the valve clearance, or is it better to have looser tolerances?

[Anonymous]

.008 is as loose as you want it. Valves tend to tighten up and the manual I have says .008 is the loosest. You will probably hear the cams tapping the shims when its running, mine do but that is better than having the valves too tight where they don't seal right.

[silverhorse47]

Loose valves run cooler than tight valves, which can be good in air cooled engines. Valves lose heat to the head while they are closed. If the valve clearances are on the upper end of the spec they stay closed longer.
But...the larger the clearance the louder they tap. Having driven volkswagens and an oldish triumph, I have grown to like the sound of my valves not burning.
S

[saaz]

Depends a bit really.

If you have the standard cams, on the exhaust side I would tend to err on the looser side. My 78 GS1000 in its younger days tended to tighten up exhaust clearances. The inlet side was relatively stable.

Remember, looser valves make a little more noise (perhaps), tight valves potentially burn out.

[brs127s]

Thanks for the replies. I have 5 of the 8 adjusted with specs now. I had to order the remaining 3 shims. None of the local shops had them. They could all order them, but they were almost double the price that Ron Ayers was asking.

[Anonymous]

Brs, note that I discovered from a dealer that the shims are the same as some old Kawasakis. If you have a Kawasaki dealer in the neighborhood give them a try.

[Don Lobacz]

Michael, the shims are not the same: they are .5 mm different. They will go in our buckets but they will snap back and forth, eventually doing damage.

[brs127s]

beware of shim sizes

Well, I got the shims in and tried to install them on Saturday. Well sure enough, one was still out of specs. After looking at my shims, the one I had installed for measurement purposes was a 2.45X. When I measured the shim with my caliper, it was a thousandth of an inch more than what a 2.45 should be. I was able to get to a dealer on Saturday and get an actual 2.45 shim and the tolerance was within the correct range. On the plus side, I am building quite a collection of shims!

So, as a word of warning, if the shim size has a thousandth digit(3rd digit to the right of the decimal), then it is bigger than the normal given size. In this instance, if I calculated correctly mine was .00254mm. And, this was a shim for a Suzuki(I think from an aftermarket kit)