Putting a 79 head on a 83 engine...

Long story short, I have a 1983 KZ650 CSR which was running fine until I installed the exhaust cam 180 degrees out and reduced my compression ratio in all 4 cylinders to zero. :sick: I found and bought a 1979 KZ650 head from e bay. Since removing my head and comparing the two of them side by side, the only problem I see with the swap is the Air Injection System on the valve cover. The 1979 head does not have the ports that connect the block/crankcase with the reed valve chamber on the valve cover. Besides this everything fits fine. Is this something that can be blocked off or do I need to somehow connect this system up? I searched for Air Injection System and read the threads but didn't find anything that specifically addressed my bike's system. While typing this I had a thought that I could probably run some copper pipe from the block/crankcase up to the valve cover for each port. Any thoughts on this would be greatly appreciated.

Are valves the same size? Are you going to replace seals in the 79 head?

I think you are going to run into some trouble concerning your camchain and tensioner system. The 79's used the older style chain and the 81's and later used the hyvo type chain. I don't know if it is possible to just use your old camchain sprockets and camcover to compensate for the differences. I'm sure someone who is more familiar with this will chime in here shortly. Steell are you out there?

Hey Bud - From what I have learned about these engines the 650's valves are interchangeable.

Pull the valves out of the 1979 650 head and put them into the 1983 650 head. As The Gringo said, due to the cam chain differences - Hy-Vo in the 1983 engine and the roller cam chain in the 1979 the heads will not be interchangeable.

I would put in new seals and you will have to lap the valves to ensure a nice seating of the '79 valves in the '83 head.

Cheers-Colin Firth-Ontario Canada

Thanks for the input! I'll have to get some seals if I swap out valves, also I'll have to get/rent a valve spring compressor. I was hoping for a simple head swap instead of a valve swap but I should know by now there is no such thing as simple or even good luck where I'm concerned!:blink: Thanks again tho!

I have no idea if the 79 head will work with the HyVo cam chain of the 83, I have never actually seen a 83 650 head.

But if you take some pics of the top of both heads and post them here, maybe we can figure it out.

The determining point is going to be whether the cam chain idler and slippers from the 83 can be fitted to the 79. If the 83 650 uses the same cam cover mounted slipper that the 750 uses, then you would have to use the 83 cam cover at least.

A 750 head ought to be a direct bolt on though.

Not sure exactly what they are called but the 83 head has two black guides that the cam chain slides against that are mounted in the block/crankcase/cylinder sleeves (whatever it's called?). The cam adjuster pushes against the rear one. Both guides extend about 3/4 of an inch into the head. Then the valve cover has a mounted guide/slipper on it. The head itself has no cam chain guides or equipment at all. The cam chain simply travels thru the head not touching anything mounted on or in the head. I'll take some pictures and post them to show exactly what I'm talking about.

Thanks everyone!

just wondering why you got a new head because the cam was 180 out? did it mess up the valves?(hit pistons and bend?)

Post edited by: 77KZ650, at: 2007/05/19 13:48

Yeah, with the cam 180 out both valves opened at the same time and hit each other. It was cheaper buying a used head on ebay than buying new valves, seals, etc. I would have wound up paying more than I bought the bike for. :blink:

Ok, here's some photos (I hope! It's been awhile since I uploaded any photos!)

First



the 83 valve cover

Post edited by: Bud1, at: 2007/05/19 14:26

Post edited by: Bud1, at: 2007/05/19 14:26

Yea! It worked!:woohoo:

The 83 head...



The 79 head...



The 79 head with the 83 valve cover sitting on it...



And finally the 83 engine...



Any input would be appreciated :laugh:

Another bit of info, after inspecting the 83 head completely I discovered the "ports" the 79 head is missing do not go into the crankcase/block but go straight into the exhaust ports. So I believe my 83 did indeed have the "Clean Air" System previously talked about in other threads and that I can safely block off the rest of that system without any ill effects.

Post edited by: Bud1, at: 2007/05/19 15:23

I think it would work, as long as the cam chain cavity on the 79 head is wide enough for the hy-vo chain you should be fine. The rear rubbing block/slider on the 83 engine sits at the cylinder base, the front rubbing block/slider sits on top of the block and the top rubbing block/slider sits in the valve cover, the head as such is not involved. The 83 cams will fit the 79 head and the valves are the same so that won´t be a problem.

What wouldn´t work is the other way around, using an 83 head a on a 79 engine - the 83 head does not have the mounting holes for the top idler sprocket assy and won´t work with a single roller cam chain.



Ooops, typo fíx.

Post edited by: OnkelB, at: 2007/05/19 15:46