Kz 1000 Head porting

Difference between 37.5 and 38.1 mm = .0236" Thats roughly 11 shim sizes.

Do your best to get all the valves even. At least all the same on each side of the head. It's a lot more professional when the shims are not all over the range.

You can fab up another block to hold a dial indicator. Use it to guage the stem heights for equal heights.

Larry,is the idea of being towards the lower end of gauge right or have i been hitting the the pvc glue fumes too hard again? :laugh:

PLUMMEN wrote:

Larry,is the idea of being towards the lower end of gauge right or have i been hitting the the pvc glue fumes too hard again? :laugh:

You're correct. 37.5mm will put you more in the middle of the shim range on a 1.110" base circle cam.

Here's the two tools I use for stem height measurement on KZ & J heads.

37.5mm = 1.476" You can adjust dial height or tip length so it corresponds to the range your after. In other words, when my needle reads .075, it's 1.475"

Not uncommon to have to take .5mm [.020"]off the stems after getting the seats straightened out.

My valve grinder has mics on it so I know exactly how much I'm taking off the tip. Works best taking .0005" at a time.

Larry

With a smaller base circle, is a valve with a longer stem needed or the valves sunk into the head further?

kzz1p wrote:

Larry

With a smaller base circle, is a valve with a longer stem needed or the valves sunk into the head further?

One of the reasons for going with a small b/c is so you can sink the stock length valves.

Another KZ option is to go J valves but that can stuff you on spring height because of the shorter overall length of the valve.

Also, with a smaller b/c, the lobe won't be as close to the edge of the bucket because the overall lobe height is shorter. Lift remains the same though.

When you install oversize valves in these KZs, you have to have a minimum distance between the valves when they are on the seats, to keep them from crashing into each other. To get this, requires sinking one or both of them.

It becomes a real pita on the intake side with a stock length valve. You wind up having to tip the valve to get it back into the shim range which can open a can of worms.
You wind up with a valve that has the keeper groove too high which makes the keeper too high and sometimes taller than the tip of the valve. This requires the keepers to be ground, etc.

We have been doing this for so long, that we know what to expect, and it is really no big deal for my head guy to set these big valve heads up so they work correctly.

The real problem, is our customers, mostly shops, that are buying all of the parts and doing their own work, or worse taking the head to an automotive machine shop.

That being the case, we will soon have available 37.5 mm KZ intake valves that are shorter than stock to avoid all the hassle.

New way cutters...
Yes I own some, and yes I screwed some heads up many years ago learning to use them.

However, there are some guys that are real artist with them. I have a customer that went to one of the motorcycle tech schools and learn how to use them. He can do beautiful work, like in Larry's photos above

One day he came into the shop with a Suzuki GS1150 head. He was doing a big intake valve job on it. He already had the exhaust side done and it was beautiful.

He had brought it in to have us bore the intake seat throats out, then he was going to blend them to the ports and do the seats. I convinced him to let me "rough in" the seats while I had it on the Serdi so he wouldn't have to try and sink them with his hand cutters. He went for it. I took the head in the back and he was visiting to one of the sales guys. I came back out in about 20 minutes and gave him the head.

He just looked at it stunned. I had the intake seats finished for him. He couldn't believe I only had it on the machine for that long.

Well now, he brings me all of his big valve stuff.

He still does the regular valve jobs with his New way stuff. He has the T handle, not the motorized driver.

You're correct. 37.5mm will put you more in the middle of the shim range on a 1.110" base circle cam.

Those were the magic words I was needin to hear. Thanks

That's good to hear Jay. When are those valves going to be available?

I've use both 37mm J and 38mm Suzuki GS in KZ heads because they're .050 shorter.