Black deposits on pistons

I use 20/50 if that's your question. I live in the desert.
Steve

I went through this on mine, did a lot of researching on lapping valves. There are A LOT of opinions on what is right and wrong. I didn't like how mine looked. Valve seals went bad and I had a TON of carbon build up. I finally got to the point that I had it apart and don't want to do it again soon so I had my head done. I thought I would have to by new valves but the guy said they just needed to be ground and to save my money. He used a machine to cut the new seats in the head (the best way to do it in my opinion) ground the valves. He said Kawasaki stock didn't do all that great of a job on the exhaust any way. I was lucky the guy only charged me I think $150 or something. You can see the before and after in my build link in my signature.

I hesitate to grind the seats. Too much material can be taken out if not done right. At least if the valves are ground, they can be tipped. Mine had a 3 angle grind and was low miles. I put in new and lapped. My old valves were used when I put them in the last time, that's why I replaced them. Works fine.
Steve

KzChop82 wrote: So- would new valves provide a thinner (proper) seat width?

No. You can not fix a valve seat issue by changing the valves. If the seat width is too wide you need to cut the seat.

As near as I can tell from the photos and what you've said, this is a fairly low mileage engine that was abused by no valve adjustment. The head cleaned up nicely but now we know the valve seat margin is out of spec and the valve face may have some cupping.

The question now is what are you expecting from this engine? Is this bike going to see a lot of use or just some occasional cruising? Do you need it to last 20k miles, 50k, what? If the bike is just going to be used gently then you can just throw the thing back together as is. If you want the engine to live for a long time, or if you want the peace of mind of doing the rebuild "by the book", then you need to find someone to perform a light valve job.

Nessism wrote:

KzChop82 wrote: So- would new valves provide a thinner (proper) seat width?

No. You can not fix a valve seat issue by changing the valves. If the seat width is too wide you need to cut the seat.

As near as I can tell from the photos and what you've said, this is a fairly low mileage engine that was abused by no valve adjustment. The head cleaned up nicely but now we know the valve seat margin is out of spec and the valve face may have some cupping.

The question now is what are you expecting from this engine? Is this bike going to see a lot of use or just some occasional cruising? Do you need it to last 20k miles, 50k, what? If the bike is just going to be used gently then you can just throw the thing back together as is. If you want the engine to live for a long time, or if you want the peace of mind of doing the rebuild "by the book", then you need to find someone to perform a light valve job.[/quote

I don't know where your getting your information from. The head gasket was leaking oil. It was determined the valve seals were leaking so they needed to be changed. It went on and on and on and on.
Low mileage motor, rebuild everything? I think not. Next time a complete overhaul. Enjoy the bike while the old components last, then rebuild it. That is unless you enjoy wrenching more than riding and have a lot of time and money to throw at it.
Steve :sick:

Steve,
Your post above is messed up and shows inside my quote. Regardless, I disagree that the only thing wrong with the engine was a leaking head gasket and valve stem seals. The photos clearly show exhaust valves that were not closing and became charred.

Regardless again, it's a fact that the valve margin is out of spec; KzChop stated the average seat width is 1.6 compared to a service limit of 1.2. You apparently don't care about details like this, and think things like service limits are unimportant. That's just fine for your bike, but don't you think KzChop should have the FACTS and weigh all the factors in his decision on what to do?

One last thing and I'll (ungracefully) bow out of this thread...
I'd like to encourage Mr. KzChop to use OEM Kawasaki gaskets, not aftermarket. Some aftermarket gaskets are okay, but others (like Athena) are downright criminal in how crappy they are. Stick to Kawasaki gaskets and know you got the best available.

A thread I had posted once a long while ago engendered a similar series of responses as this one and I received one piece of advice that was head and shoulders above all others by a well respected member on this forum and this is what he said..............."To measure is to know, and once you know you make your decision" these motors can run on sloppy tolerances BUT if you want them to run well then you adhere to service limits and tolerances that were designed into them
My >02

First off, the gaskets are important. Buy quality.
A complete overhaul was not indicated. That means pistons, cam assy, valves, etc were still usable. Only the valve seals were the issue. After all this back and forth, the only remaining issue is .5mm of valve surface being out of spec. This engine will have to be redone in another 10/15000 more miles, maybe more. By that time, the bottom end will need attention. Maybe.
Some people don't argue for a reason, they just argue.
Steve

Patton wrote:

KzChop82 wrote: So- would new valves provide a thinner (proper) seat width?

Perhaps, if the seat was already perfect, and the existing valve faces are beyond restoration. The new valve's perfectly smooth and presumably 45° cut would nestle inside the perfect seat whereby the contact area would be within spec and neither too thick nor too thin.

Much may be learned about the valves, valve face, head thickness, stem length, seat angles and seat-cutting tools, specs, service limits, etc., by downloading the Z1 FSM from KZr's FILEBASE:

click here > www.kzrider.com/filebase/search/finish/1...asaki-service-manual

Start at page 77.

If there's sufficient valve-head thickness, the existing valves (if unburned and uncracked and unbent and otherwise restorable) may likely be re-ground, and stems tipped if needed to gain additional clearance, without needing to be replaced with new valves, whereby the existing valves will have regained their as-new 45° faces..
Basically, the valve face is designed to have a 45° cut, which grinding should produce, along with restoring condition of the face. This 45° surface on the valve face is what mates against the 45° surface in the seat.

The valve seat (incorporated into the engine head) has several angled surfaces, one of which contacts the valve face, to form the contact area between them when the valve is seated in the seat (which is the spec size or too thick or too thin reference in the earlier posted diagram).

Valve cutter tools mentioned in the FSM are used to re-surface the angular cuts in the valve seats -- not used to cut the actual valves themselves.
I suppose it would be correct to say that seats are cut and valves are ground.

If the existing valves are in decent condition with smooth 45° faces, perhaps cutting/resurfacing the seats would produce a thickness of the measured contact area seating width to within specs as provided in the FSM covering the 1982 kz1000 csr M2.

Apologies for where there's repetition of what's already been mentioned and better said by other members in earlier posts.

Good Fortune!

Yes what a discussion! Good head is hard to find! :laugh:
This is a virgin, late 73 Z1 head with the casting for the early vacum nipples. 1st time ever taken apart. lots of meat on the valve face. exhaust guides are shot.
This is what it looks like before I media blast it. which is after a solvent bath to get all the oil out. And then an oven dry it out. Glad I only do this for a hobby and not a paycheck.

Whats with the half cam shaft?

swest wrote: Whats with the half cam shaft?

Thats for checking cam bearings, 1 cap at a time, no lobes either. Can't screw nothin up :lol: