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Pull the Oil Cooler and block all the pasages for the hoses and see what happens. You don't need an oil cooler on a stock motor. See all the previous posts about driving through Death Valley for reference!

If the oil cooler was picking up oil from the wrong spot or bypassing it from getting to the head. It's very possible you could get overheating before the valve wear etc. Since you know you have a problem related to the head, and the oil cooler really isn't needed go ahead remove the cooler and see if the overheating occurs. If this solves the problem start figuring out how your oil cooler hoses are setup wrong!

I do have an oil cooler on my KZ650, but I installed it after I modified the engine, big bore kit, higher comp pistons, cams, etc. Even still I have ridden it in unbeleavably hot weather, 120+ degrees and never had a problem with overheating.
I has been my experience that when you install something new on your engine and just after you install it something else breaks or starts to not work properly it is probably the item you installed.
I agree with Old-Skul I would remove the oil cooler and see what happens then.

Sorry about my advice to use gasket sealer. I meant just a little if the gasket didn't have the sealer type stuff around the center as mine always have. I've also ridden close to 120 degree temps for many miles on a KZ650. Once when the orings leaked really bad after a long ride through these temps after removing the head, the orings were basically melted to the head. Don't know what temp the head was at, but it wasn't good. After that I did the unthinkable and put Yamabond #4 on those orings and the edges of the head gasket in that area and never removed the head again on that engine. 30,000 miles when orings melted, 165,000 when engine retired due to sludged up Castrol GTX oil condition.

I agree that if the head wasn't getting oil it would get hot. At one time I thought I wasn't getting oil to the head (for a different reason). After running the engine at mid rpm for a few minutes, pull the valve cover there should be oil still at the bottom of the cam area, expescially(sorry can't spell tonight) by the cam ends where it can't drain down. Also check the cam bearings as no oil will cause bearing failure and scarring. The oil in the head comes from the hole in the cam bearings/journals (really can't spell).
The oil cooler should have both ends at the oil pressure light sender.

Post edited by: tfh903, at: 2006/01/07 00:43

Well maybe the cooler is to blame and as you all have stated it really doesn't need it though I do ride in 100 degree weather almost every year. It seems strange that this would be a problem since I used a gpz oil pan to give me the ports for the lines. Maybe the cooler itself is clogged! Although I thought I check that before installation.

Thanks again

One more thing. How far out is too far out when measuring the head for warp? The factory is pretty tight and I've heard you can go beyond their recommendation. Who's gaskets are best? Should I follow the factory instructions with regard to using sealant or the lack of it?

jimi

Latest Update! Well the head isn't bent after all and the culprit is stripped threads on the forward center bolt hole (right where it was leaking). After replacing the threads on the cylinder with an insert I plan on replacing the studs/nuts as well just as a precautionary measure. But now the head needs valve guides! Anyone have a head for this thing? Thanks for all your advice!

Jimi

You said that the center of the head is warping upward.
Now you are saying that a center bolt is striped. It appears odd that several or more heads have been removed and this was never discovered. How could this bolt be torgued if the threads are striped ?
Generally a head warping/leaking in the center is a result of using the wrong torgue pattern, IE: torguing the outer bolts too much before the center bolts.
Harry