1980 KZ750 LTD H valve shim question

Hi guys and happy holidays.

I've just had my valve seats machined and I have bought all new exhaust and intake valve stems, my question is what size shims do I start with? I had a baseline before disassembly but with new valve stems and new seats will the original valve clearance values even be relevant?

Thanks for the help.

Brad

The old shim sizes will not be relevant anymore. Since the seats were cut you can expect that the new shim sizes are most likely going to be thinner than the old shims. The new valves will restore a little of the clearance but most likely not enough to make up for the cut seats. At any rate, it's nice to have some thin "checking shims" you can install and get a measurement, then calculate what the needed clearance should be.

Thanks for that, I have a lot of thicker shims but not as many thin ones. If anyone wants to do swap lemme know.

Cheers

I've got some thin shims I'll never use. Are you located in the USA? That "cheers" reference suggests maybe not...

I'm in Canada with an English wife, hence the cheers, I have a US post box though cuz I live right on the border.

thanks

You may have to have the valves "tipped".
Steve

swest wrote: You may have to have the valves "tipped".
Steve

CORRECT! I wish I would have thought to ask my machine shop to grind a few thousandths off my valve stem tips. Why? Because I have dozens and dozens of #270 through #300 shims and after the valve job, I had none thin enough to make it work and I ended up sourcing lots of #220 through #250 to get the head back in spec.
What a pain ....in the middle of riding season!!

braddlesnake wrote: I'm in Canada with an English wife, hence the cheers, I have a US post box though cuz I live right on the border.

thanks

Checked the spares box and found some thin shims my good friend Koolaid Kid (George) passed my way. Got 4-2.30's, 3-2.25's, and 1-2.20. Install those and then you should be able to measure some clearance at your valves and calculate what actual shims you need. I'll trade you these things for something fatter shims in the 2.40 - 2.70 range. PM me if you want to discuss.

missionkz wrote:

swest wrote: You may have to have the valves "tipped".
Steve

CORRECT! I wish I would have thought to ask my machine shop to grind a few thousandths off my valve stem tips. Why? Because I have dozens and dozens of #270 through #300 shims and after the valve job, I had none thin enough to make it work and I ended up sourcing lots of #220 through #250 to get the head back in spec.
What a pain ....in the middle of riding season!!

I used my bench grinder to shorten valve stems. I was turning valves while grinding. Instead of flat tops I got cones. I adjusted valve clearances to smallest spec, considering that cone tops can wear out.

Obviously, I could be wrong, but wouldn't the contact area of a cone shaped valve stem tip have less surface area than that of a flat valve stem tip resulting in higher PSI at the point of contact, and if that is true, would it not concentrate more force on a smaller spot on the shim which possibly could cause a crack or other shim problem? Just curious. Ed

Not the way to do it. :whistle:
Steve

I adjusted valve clearances to smallest spec that sounds like a great idea too.