Best way to test 0 clearance valves?

Hello, wonderful KZRider crowd! My own newbie adventure in maintenanceland is coming to a close, held up only by a legion of tiny, time-consuming projects! I've got the head back on, I put the camshafts in today and, following the advice of the mechanic who lapped my valves (sounds dirty!) I measured the clearances following the procedure in the articles here on this site.

I haven't checked what shims are in there yet, but the measurements I got are as follows

Exhaust
1: 0.063 mm
2: 0.178 mm
3: 0.076 mm
4: ZERO clearance

Intake
5: ZERO clearance
6: 0.076 mm
7: 0.102 mm
8: ZERO clearance

I noticed that the four outer valves are the tightest, including 3 which now have no clearance (couldn't even force the 0.038 mm feeler in there). Odd coincidence or does this happen often?

I'm pretty confident I know what to do with the other 5 valves, but what's the best way to test the ones with zero clearance? Pull all the buckets, remove and measure all the shims, insert the smallest one into each of the zero clearance valves and go from there? It's a drag you have to reinstall the camshafts every time you test.

Help me out, o ye sources of KZ experience and wisdom! (How many decades of KZ mechanic experience do y'all think we have on here? I can offer .25 years.) The fewer times I have to torque wrench the camshaft caps on, the better!

Pop the shims out & if marking is still on them, order the next 2 sizes thinner...

If no markings then use a digital caliper.... Actually prefer this method better....

Z1 has shims...
www.z1enterprises.com/catalog.aspx?pid=KZ650-B1-1977-EN1

EDIT: Just realized you most liekly have 13mm shims KZ650....

Can you rotate the buckets on the valves with zero clearance? If so, then you have some minimal amount of clearance and you can reduce the shim on those valves by 0.1mm.

If not, then there is no clearance, and you should replace that shim with one of the smaller shims that you have from another valve. Then you should be able to measure the clearance from there.

Last, what model bike is this? Does it have the shims on top of the buckets a-la KZ1000? If so, then you can get a tool that will press the bucket down and hold it there so that you can get the shim out without removing the cam. Like this one:

www.z1enterprises.com/detail.aspx?ID=152

If dealing with over-bucket shims, meaning visible shims atop buckets where cam rides on the shim, such as large Kaw fours ---

On those with ZERO clearance:
With cam lobe pointing away from bucket, see whether the shim will turn (indicates minimal clearance), or whether it won't turn, being too tightly held by the cam base (indicates no clearance).

If shim will turn, would replace existing shim with next size thinner shim.

If shim won't turn, would replace existing shim with shim two sizes thinner.

Gap on exhaust #2 is a little too wide. Likely needs two sizes larger shim.

It may be possible to swap exhaust #2 and the 4 zero clearance shims around to achieve clearances within spec on those needing adjustment.

Good Fortune!

EDIT:
Just noticed: Pull all the buckets, remove and measure all the shims, insert the smallest one into each of the zero clearance valves and go from there? It's a drag you have to reinstall the camshafts every time you test.
So likely dealing here with shim under-bucket, whereby above suggestions for over-bucket won't be very helpful.

It's helpful and easy to add bike make and model in signature.

Click here > kzrider.com/index.php?option=com_kunena&...d=8&id=382004#382317

Good Fortune!

Great idea! Change made.

Yes, I have shims under the buckets on my 1983 KZ750 L3 4 cyl ( at Patton). I tried spinning the buckets with my fingers but they went nowhere. I'll be a little more thorough next time. Supposing I have zero clearance, I'll try to do something clever so I don't have to order a whole fleet of shims at $5 each.

I was just hoping there was some trick for this scenario since, for any other measurement, math is sufficient.

Make sure to note what shims are in what valves after you do get it sorted. That way, when doing future clearance checks, you'll only have to take the cams out one time to change shims if necessary. Make up a little chart and keep it in a safe place. Also don't forget that you can usually swap shims around to achieve optimum clearance on most valves and then order only a few shims. I had to make an adjustment on most of my valves on my rebuild, but only needed to order 3 shims. I just played three card monty with my shims.

If you cannot spin the shim, then assume zero or slightly less than zero for clearance. So you are looking at a two shim size change on those valves.

Most times that's going to be fine.

If you did end up needing an even thinner shim, you are likely to have valve seat damage and chances are you would not get good compression after correcting the clearances.

Running an engine with valves that don't close fully causes hot exhaust gases to work past the valve - this causes 'burning' of the valve/valves seat.

This is all assuming the reason for the zero clerance is normal wear. If a previous owner reinstalled cams with the shims shuffled, is would be anyones guess as to what to use without installing thinner shims and rechecking.

Alright, I'll go two sizes thinner (.1mm, correct? From 275 to 265, for example) on those ones.

I'm gonna guess that what happened here is the valve lapping and seating surface work brought the valves in a little closer than they were before. I don't believe this was happening before I got that work done (although bad compression might explain why I only got 37mpg)

I will not be running this engine until the clearances are within spec. I think I'm gonna aim for .07mm to .08mm clearance, given that people all say the clearances shrink after the first few runs.

staniel wrote:

...gonna guess that what happened here is the valve lapping and seating surface work brought the valves in a little closer than they were before. I don't believe this was happening before I got that work done...will not be running this engine until the clearances are within spec. I think I'm gonna aim for .07mm to .08mm clearance....

What are factory specs for valve clearances on 1983 KZ750 L3 ??

Where thinner shims aren't available, it may be feasible to grind down (tip) the valve stem, which slightly shortens its length and thereby allows a thicker shim.

Must carefully follow FSM instructions about such procedure.

Good Fortune!

Curiously, my Clymer manual says

1983-on Non-turbo
Valve/guide clearance (rocking method)
All valves - 0.013 in - 0.33mm

This sounds extremely high for what other people's bikes are requiring here (generally 0.5mm-0.15mm).

Does this sound normal for a KZ750L3?

The guy at this thread says the clearance spec is .08-.18...
kzrider.com/index.php?option=com_kunena&...d=2&id=226002#226145

Any guidance would be greatly appreciated. Meanwhile I'll do math to try to get the clearance to between .10 and .13.

Shim measurements, for anyone curious, were

Ex
1. 260
2. 250
3. 250
4. 260

In
5. 245
6. 250
7. 240
8. 250

staniel wrote:

....I don't believe this was happening before I got that work done (although bad compression might explain why I only got 37mpg)...quote]

37 mpg is not bad or unusual although some folks report getting better. My '77 KZ650-C1 has never gotten more than that since I bought it new (granted, I drive a little bit on the spirited side). Ed