Black deposits on pistons

Yes but if you can do. That exhaust valve looks like it has a ridge on it.
Steve

swest wrote: Yes but if you can do. That exhaust valve looks like it has a ridge on it.
Steve

That's what happens when you lap aggressively. Lapping should only be used for minor clean up. Not for heavy cleaning or resurfacing the parts.

If the valve DOES have a ridge on it, it wasn't caused by lapping. I'm still waiting on an answer.
Steve

swest wrote: Yes but if you can do.

I'm reading this at 6:30am, maybe my brain hasn't started yet.
So- it is safe to reuse the rings, correct?

swest wrote: That exhaust valve looks like it has a ridge on it.

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KzChop82 wrote:

swest wrote: That exhaust valve looks like it has a ridge on it.

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[/quote

The ridge is at the bottom. Looks like it's starting to form. A better pic would help. You can reuse it if the seating area is even. I could have reused mine but I found a deal on some Doremi valves made in Japan for $130 shipped.
I was hoping to gain some adjusting room. I did on the intake but not on the exhaust, I lost some there due to the carbon build up they were seating on. The constant oil seepage kept them from burning. It only smoked at start up and cleared but the intake caused oil fouling. The KZ 1000 are slightly larger and the seller is number 35 at eBay. He's re listed more for mine, I bought the last set three months ago, you might ask if he has your kind if you decide to go new. The intake valves are a little lighter than stock, the exhaust appears the same. They and the springs, my compression is up, crisper throttle responce and better acceleration. What's most important to me, no oil fouling.
That piston is just a example of what happens when something goes wrong. It can be oil starvation, broken rings or lands, dislodged cir clip, or too many dry starts.
In my case being on a fixed income, I sometimes have to make do with what I have. That's what I meant by "if you can, do".
Ness has good examples of worn valves. Yours don't to appear to be that bad. Your configuration allows you to freshen up the top end at will. I'd put it together and run it for another 15,000 miles.
This time I not only did the top end but also went through the oil pump, got a low mileage transmission, back cut it myself and replaced old parts before they failed. The crank was checked and welded years ago. That cost $200 and I had it done while I was in there.
New rings/new valves, your choice.
Steve

KzChop82 wrote:

swest wrote: That exhaust valve looks like it has a ridge on it.

Attachment image_2015-01-11.jpg not found

[/quote

The ridge is at the bottom. Looks like it's starting to form. A better pic would help. You can reuse it if the seating area is even. I could have reused mine but I found a deal on some Doremi valves made in Japan for $130 shipped.
I was hoping to gain some adjusting room. I did on the intake but not on the exhaust, I lost some there due to the carbon build up they were seating on. The constant oil seepage kept them from burning. It only smoked at start up and cleared but the intake caused oil fouling. The KZ 1000 are slightly larger and the seller is number 35 at eBay. He's re listed more for mine, I bought the last set three months ago, you might ask if he has your kind if you decide to go new. The intake valves are a little lighter than stock, the exhaust appears the same. They and the springs, my compression is up, crisper throttle responce and better acceleration. What's most important to me, no oil fouling.
That piston is just a example of what happens when something goes wrong. It can be oil starvation, broken rings or lands, dislodged cir clip, or too many dry starts.
In my case being on a fixed income, I sometimes have to make do with what I have. That's what I meant by "if you can, do".
Ness has good examples of worn valves. Yours don't to appear to be that bad. Your configuration allows you to freshen up the top end at will. I'd put it together and run it for another 15,000 miles.
This time I not only did the top end but also went through the oil pump, got a low mileage transmission, back cut it myself and replaced old parts before they failed. The crank was checked and welded years ago. That cost $200 and I had it done while I was in there.
New rings/new valves, your choice.
Steve

This program is acting lame, keeps jumping around and double posting. Good thing I've mellowed with age, I'd be working on my lap top now.

Grinding the seats is to be done when it absolutely necessary. On these heads, there is a small window of wear available without having to grind the end of the valve, etc. I refer you to the sunken valves thread a few months ago. That head was ruined by someone that didn't know what he was doing or didn't care. It went on and on and it became obvious the poster just wanted to bash someone, not accept the fact he had to find another head. Sure it could be fixed, but a used one done right would have been better and cheaper. It became a case of mutual combat and a damn near free for all. I don't remember if the accused had a chance to defend his work or not. That thread was closed down.
Steve

Look at the width of your contact area, which is the valve seats 45 angle sealing area. You can use a sharpie magic marker on the valve face and rotate it against the seat to see the sealing area. Compare this to your spec in the service manual. Take your stuff to a machine shop for a consultation on your parts. I have yet to see anyone post on Valve Margin. If the valve gets re-surfaced, and the margin becomes to thin, its junk. EX valves take most of the abuse, and often need replacement. Seat cutting should be left to a machinist, they will make sure the guides are good before doing anything with the seats. Also where the seats sealing surface ends up on the valve face is critical, as well as installed height to make sure you're in shim range and spring pressure. Definitely use New Piston Rings, with the correct cross hatch finish and clearances. Make sure the bore is true. Don't re-use the piston pin cir-clips, they are cheap compared to what can happen if one decides to come out.

I agree with what was said above but if the valve and seat are even and being it's a low mileage engine, I'd put it together with the new seals, springs, rings, and cir-clips too. If they aren't damaged they can be reused but if ordering new rings get the clips as well.
Your choice.
Steve