cylinder pressure

I have an '88 KZ1000P with 160 miles on it. Since it's winter, I decided to check the bike. I measured the cylinder pressure and it came out
1 - 170psi
2 - 137psi
3 - 135psi
4 - 165psi
Should I repair it before disassembling and measuring? Where can I find parts?

When were the valve clearances last checked ?
160mls ??
How regularly is it run ?
I would suggest check the valve lash, drop some WD40 in the bores and let it soak (remember to spin it over with the plugs out to clear the WD before starting) start the motor and run up to temp then check again (make sure you have the throttle wide open when testing) I wouldn't suggest "diving in" until you have a better idea of whether or not you need to

Sorry, 160,000 miles.
Valve clearances checked and OK.
Checked with the throttle open.
After pouring a small amount of engine oil into the cylinders, the reading is 190-200 psi on each cylinder.

GrzegorzSadoch wrote:

Sorry, 160,000 miles.
Valve clearances checked and OK.
Checked with the throttle open.
After pouring a small amount of engine oil into the cylinders, the reading is 190-200 psi on each cylinder.

That does then suggest worn bores (not surprising at that mileage)  I guess the next step would be to pull the cylinders and measure "how much" wear there is before deciding on a strategy. These readings seem high for a stock motor, due you trust the gauge ?

So I'm going to have to disassemble and measure the cylinders and pistons.

I wouldn't touch that engine.  135 psi will run fine.  Put a few hundred miles on the bike, then check valves and compression again.  It may bump up, but even if it doesn't, that's not low enough to warrant a teardown.

I concur with Nessism, don't tear that down and just run it. Try something like marvel mystery oil or similar (WD40) in cylinder #2 and 3 and ride the piss out of it.

Tear downs, even just top end deals are so expensive these days, you need to think twice about it. 

I would suggest a test with several different compression testers, and then if you not happy a leak down test is in order.

You can't dispute a leak down test, and the equipment may be on par with gaskets/rings/seals etc. or even less. Even if it comes back with bad news, the upside is you will still have the leak down kit.

A friend of mine has a KZ900 bored to 1015 and it ran on 130 PSI for a bunch of years before he did a tear down and bought new pistons. I rode that bike on 130 PSI and it was totally OK, it would not pull your arms out of the sockets but you could get a major speeding ticket on it