Top end oil leak

Hi everyone,
I have a 77 KZ650B1 with 128K on it and I drove it off the show room floor. Just a little history on the old girl, I finally had to take her down at 111K and do some work. Didn't have to do much, rings, valve job, starter clutch and a few minor parts otherwise the rest is still virgin material.
Just recently I developed an oil leak. The oil is pushing up from the cylinder stud on number 1 outside rear. Do you think it is leaking from the rubber O ring that is between the cylinder studs?
Looking for some help before I pull the head.

Wow; another original 1977 KZ650 owner! Welcome aboard; there aren't many of us around. Regarding the leak, if you clean the cylinder head / cylinder joint really well you may be able to tell after a ride if oil is weeping from the center of the joint (see yellow arrow) or from an area near the rear of the engine. If it is weeping from the center it may just be the o-ring. Is yours just weeping a little or is it actually dripping after a ride? Ed

At 128,000 miles by all odds every oring should be leaking like 126,000 miles back, so you are lucky if this is the first one. The place Ed mentions is that oval oring that is notorious for leaking. I don't think any orings on the studs themselves ever cause problem. Main leaks are this oring, the tach drive, oring between the cylinder and cases, orings between the pan and cases, orings to seal the covers for the transmission gear assm, of course the cam end plugs. These are just the main ones. Kawasaki used a lot of rubber orings, and all get old, and get old faster with heat and miles and will leak. High mileage to keep leak free is an ongoing battle to say the least. This your first leak?
The old 77 I ride now I just wear old clothes and my legs get oily change jeans every day is easier. OK, don't mean to degrade the question any further. Chances are what Ed says is correct.

Ed,
I have traced it down and it is coming up around the head bolt just to the right of your arrow and it comes out at a good rate after she is warmed up. Still think it is the oval o ring in the center?

Thanks, Maybe I am lucky but I replaces all seals and gaskets when I took it apart a few years back but never had any leaks up till then and this is the first.

johninwi wrote: Ed,
I have traced it down and it is coming up around the head bolt just to the right of your arrow and it comes out at a good rate after she is warmed up. Still think it is the oval o ring in the center?

Hard to say, maybe not though. After you ran the engine some did you let it cool down and re-torque the head? If not, that might be worth a try before pulling the head. Ed

Ed, yes I did re-torque the head and it has been three years and just a few weeks ago it started leaking.

Well everyone I pulled the head of today and have ordered new head gasket. o rings.
Hope this cures the problem.

Well Ed I got it back together tonight and it still leaks right up the #1 outside rear cylinder stud. Replaced O rings, head gasket. don't know what to do now.

Well what did you do to fix it? I have the exact same problem on my 76 kz900. Oil coming up around both front outside head bolts, All new gaskets and orings.. got it tore back apart, not sure what to do now.... :blink: :blink: :blink: