A sad story

Last winter I did a lot of work to my 75 Z1B 900. Motor has only about 22K on the clock. My youngest daughter brought her B/F home for the wife and I to meet. He comes from a Gixxer. He wanted to ride the Z1 to see how it compared to his buddies 76 KZ 900. We get back to the house and the Z1 is making noise like it had a case of loose valves. The B/F told me he did not realize the red line was so low. I was due for a valve check anyways and thought nothing more about until I did the valve check and found all four intake valves were bent.

OK, I ordered new valves and keepers, springs all around, new guides and seals. When I got the refurbished head and was told there were no specs on valve length. Fast forward. Head s on, cams timed and we decided to do a valve check with the motor still out. Exhaust was easy to do, swapped a few shims around and they are done.
The intake valves are another story. The thinnest shim I have on hand is a 230. No go, too tight. I tried a 230 in all 4 intakes and a 230 was too fat. OK I can order shims down to .200 and will try those. My concern is this. I have never seen valve checks get thicker, always thinner. If I end up too close to the thin end of the shims, my fear is I might run out of shims to gain clearance. I would rather be in the middle of the shims if anything.

Should I burn a head gasket and have .020 or so ground off the end of the stems? Thanks in advance for your opinions. Tim

There is a spec for the installed height, as well as a minimum distance from the valve tip to the retainer groove. I wouldn't take off .020" that's way to much. You probably only need .004-.006" to get you set up.
You need the Factory Service Manual, it will have all of the info on it.
I don't know which springs you bought, but APE sells a good set of replacements with a bit more pressure. Might save the valves from a bad down shift, or another Gixer rider.
ape-store.com/shopsite/page38.html

Thanks Motor head. I happen to have a 1st addition of the Z1 service manual from Kawasaki. I'll have to sped some more time in there and find those specs. The manual I gave the machine shop guy didn't have it. The real shop manual has been bought since then.

The springs are good after market dual springs which high lift cams can be used and could very well be APE. Tim

That's just one more reason I NEVER let anyone ride my bike! Ed

It is exhaust valves that contact pistons on an over rev as the piston is chasing the exhaust valve home. Bent intakes sounds like a timing issue.

Any good cylinder head shop would have had the valve stem length well in the shim range.

Yeah, Ed, I was trying to be a nice guy. Of course it ends up being my fault. There is a possibility it could have jumped time but I was always pretty good at adjusting the chain tensioner often. Tim

Any good cylinder head shop would have had the valve stem length well in the shim range.

I agree but I live in a rural area and I went to the best machine shop in the area. The guy does great head work on your car....Tim

Z1Driver wrote: Any good cylinder head shop would have had the valve stem length well in the shim range.

I agree but I live in a rural area and I went to the best machine shop in the area. The guy does great head work on your car....Tim

Lots of cars also take shims. Hundreds of Millions of Toyota's out there do, not to mention many many others.

the higher the total valve / stem length the smaller or lower the shim number.

If you remove the valve and reduce the total length of the valve you will open up the clearance and in turn need a taller shim.

the ideal shim height would be in the middle about 255 to 265

I you remove to much stem....you will cause a problem with the valve keepers. the tip of steam should never go below the top of keeper.

The machine shop needs the factory Kawasaki measurement and needs to bench test the valve clearance or shim clearance if they are unfamiliar or not with the process.

If you pop the head you need to replace the head and base gasket. Just cant get head off without disturbing the base gasket. I would remove head and then grid the valve stem to correct length then bench test. If you are 255 to 265 you are good. My head is set at 265 so you can get to 265 no problem.

The only person who gets to ride my bikes is my dad. I don't trust anyone else.

My 900 likes that red area on the tach. :whistle:
I don't know if it is just mine but the power does not even begin to drop off until 10,000. My handy gopro tells me that I leave first gear at 11,000-11,200 all the time. I leave second at at least 10,500.
I don't know if that's normal as I have not ridden many KZ's or if it's just mine.

Z1Driver wrote: Last winter I did a lot of work to my 75 Z1B 900. Motor has only about 22K on the clock. My youngest daughter brought her B/F home for the wife and I to meet. He comes from a Gixxer. He wanted to ride the Z1 to see how it compared to his buddies 76 KZ 900. We get back to the house and the Z1 is making noise like it had a case of loose valves. The B/F told me he did not realize the red line was so low. I was due for a valve check anyways and thought nothing more about until I did the valve check and found all four intake valves were bent.

I would have killed the idiot.

Probably the only reason for gun control....... :ohmy:

WOW!!! 11,000-11,200 rpm? Mine runs best shifting right at 8500 rpm. I've tried different rpm levels to shift and I always seem to run best shifting at 8500 rpm.