82 GPz 750 leaking head gasket

Hi folks. I'm new to the forum, and I've recently bought a 1982 GPz 750, otherwise known as a KZ750R1, I believe. It's a pretty solid bike, a bit over 14,000 miles, runs very well, but it's leaking oil at the head gasket on both sides, just left of the number one cylinder and just right of the number four. Does anyone know if this was a particular problem with this engine, and more importantly, is there a fix to attempt before replacing the head gasket? Assuming I have to replace the head gasket, is it a nightmare or fairly straight ahead? I have a fair amount of engine experience, but, I've never worked on one of these engines. Thanks in advance for any input.
Richard

Welcome Richard...you have a great bike (I'm biased, of course)! Your immediate course of actions should be:

1. buy a Kawasaki Heavy Industries shop manual... readily available on eBay (expect to pay US$15.00 to $40.00, depending on bidding interest).

2. buy or borrow two torque wrenches (one in ft/lbs and the other in inch/lbs) and retorque your head as per the tightening pattern and specs in the manual.

3. if that doesn't stop the leaking, then return to the manual and really get to know your motorcycle. A tear down and top-end freshening is quite do-able by anyone even with a moderate mechanical inclination. All the necessary parts are available and tools can be fabricated, borrowed, or purchased:)

Welcome murphus. You will find kzr a very helpful community of Kz enthusiasts.

Changing a head gasket isn't too big of a deal but before you tear into the motor's top end I would suggest checking the torque specs on the head bolts.

On my 650 this involves pulling the tank off and getting a long socket and extension for the torque wrench. Your 750 should be the same. From memory there are 16 nuts to torque, 8 on each half of the motor. Once you have retrorqued everything take a pressure washer to the motor to clean off the old oil. Let the engine's surface dry then fire up the motor and let it warm up slowly building up the rpm's. You will see if this re-torque solved your problem by a lack of new leaking oil.

Should you have to pull the valve cover, cams and head, be very careful to mark which bucket and under- bucket shim goes into each of the individual cylinder's intake and exhaust valves. You don't want to lose any of the shims which sit atop the valve stems.

You can go to www.buykawasaki.com to get parts diagrams. Follow the owner's links. If you need any parts get in touch with Jeff at Z1 enterprises. Jeff is a member of kzrider.com and is extremely helpful.

Cheers-Colin Firth-Ontario Canada

The head gasket never goes bad (well never usually), but what does go bad are rubber orings that seal the head to the cylinder for the oil gallerys at the points you are leaking. This is a very common thing on the KZ650/750. It happens from hardened rubber from heat and age. There are tons of these orings on these engines and the ones that run the hottest will go bad first, then others will follow on high mileage motors which your's is not. It's not that bad of a job to replace these, but you do have to remove the head, which means a new head gasket plus the 2 orings.

What they said!

Great help, one and all. I have torque wrenches and such, so the retorque is no issue. It's interesting to know about the o-rings on the head, Ron, and I'm certain your correct that's where my leak lies. I find it highly instructive to pick the brains of folks who are well versed in a particular machine before I step in and butcher it! You guys are great, thanks.

One other question, and that is, I'm under the impression the cam chain on these engines is staked, as in there is no master link. True?

Richard in Lawrence, KS

murphus wrote:

One other question, and that is, I'm under the impression the cam chain on these engines is staked, as in there is no master link. True?

Richard in Lawrence, KS

The camchains are endless with no masterlink.

I just changed the O-rings on mine. The previous ones shrank and hardened

kzwolfsr:

When you say you just changed the o-rings, did you simply unbolt the head, lift it, change out the o-rings and torque it back down? Without replacing the head gasket?

Richard in Lawrence, Kansas

Yep I did. Well this time I had a new gasket but I took my head off before and didn't change the head gasket and the bike worked pretty good till I had ignition and valve clearance problems.

I've done this job probably 7 or 8 times over the years and I always changed the head gasket "because you have too". Well, I got tired of rediculous head gasket prices (upwards of $100 for one gasket if you go oem Kawasaki) and I too just replaced the orings, put the old gasket back on and all worked out fine. I wasn't going to mention it because it's one of the written in stone things that you can never, ever even *think* of reusing a head gasket. Guys do that annealing, or whatever it's called, with copper head gaskets that involves heating them up red hot then dropping them in water but I don't think that would apply here.

All very interesting. And yes, I've actually annealed gaskets, used to ride Nortons and it was common practice, but those were solid copper gaskets. So when you do pull a GPz head, what's the trick for removing the cam chain? And putting it back together?

Richard in Lawrence, Kansas