KZ650 engine block interchangeable btwn years?

Hi all,
Had a horrific night recently. A ratchet strap & hook got got unhooked from my rack, caught on the chain, and were sucked into the transmission. Thankfully, the first thing that happened is that the chain dropped off the rear wheel, so it all just slowly glided to a stop as I lost power, but it's an awful mess in there - enough to have ripped the shifter cover clean in half. Some of the transmission is chewed up, and moreover, the engine/transmission block itself has parts cracked off of in places. I'll have a hell of a job over the winter rebuilding it, but I need to start with a new crankcase (possibly just the bottom block). I have a 1980 KZ650 F1. I'd like to salvage as much of what I've got in my case as possible, and I see a number of crankcases up on ebay for reasonable sums. My question is whether I can swap in an engine block from another year/model?

Other general advice is welcome - I'm mechanically inclined, technically competent, and do my own maintenance work, but have never undertaken anything near this large a project. For example, is there anything to look for when purchasing, other than major damage such as cracks?

Sorry to hear about your mishap.

:ohmy:

I've always read that you need to keep, and use the top and bottom halves of the crankcase together, and should not mix top and bottoms from different engines, as the halves are bored for the crank etc with the crankcase together (top & bottom).

This being said, Andy on the 650info forum has recently assembled an engine with mixed top and bottom cases, and so far no issues.

If you can get them as a set, it will go much more smoothly.
Steve

Thanks, I hadn't though about the fact that they would be bored together. Is this really an issue? That is do the pistons drop down into the bottom end at all?

rstnick, I'll be sure to heck out andy's projects on 650info

The major difference on these 650 motors and the KZ750 of various years will be which type of timing chain they have. That changed around 1980, I believe, and means the crank is different because of the timing chain sprocket and then the head is different because of the lack of an idler wheel for the chain up top on the newer version. The cam sprockets are also different but I believe the sprockets are interchangeable. I think the barrels may be different because of the tensioner set up, but I can't remember for sure on that one, it's a long time since I looked at all that, when I was looking at using GPz750 parts to make a 750 motor for my KZ650. If you have the later type, I do have upper and lower cases from a GPz750 that could work. I also have a complete 78 KZ650 motor Either way it would be easier to get everything from the right year bike rather than mix and match.

Sorry to hear about your bad luck too

So I had a look at powersports warehouse website
www.powersportswarehouse.com/p/Kawasaki

found the cat # for the crankcase, plugged it into the search box, clicked on where used and got the following list
KZ650-B1 (1977)
KZ650-B2 (1978)
KZ650-B2A (1978)
KZ650-B3 (1979)
KZ650-C1 Custom (1977)
KZ650-C2 Custom (1978)
KZ650-C3 Custom (1979)
KZ650-D1 SR (1978)
KZ650-D1A SR (1978)
KZ650-D2 SR (1979)
KZ650-E1 LTD (1980)
KZ650-F1 (1980)
KZ650-H1 CSR (1981)
KZ650-H2 CSR (1982)
KZ650-H3 CSR (1983)
KZ750-H1 LTD (1980)
KZ750-H2 LTD (1981)
KZ750-H3 LTD (1982)
KZ750-H4 LTD (1983)
you might want to double check

Looks like cases from a 750 would work also. You might find it easier to just swap in an entire motor

Sometimes those lists are kind of a stretch. I believe 1978-80 KZ650 will all work, 1977 is a little different due to the charge system, and dowel placements are different so mating a 1978 and up stator cover on the 77 cases doesn't bolt up, but can be made to work with a drill. I would just find a good used engine from a 78-80 and swap in.

aenikolopov where do you live? As I said I have GPz 750 cases top and bottom and a complete 78 KZ650 motor. Also have the 750 barrel and pistons, so you might be able to up capacity too, if the cases would work. The cases would obviously be more shippable, but I can't see if you are even in the US from your profile.

redhawk4, I'm in new york city. You?

It just seems such a shame to replace the whole engine for damage only to the bottom end. Is this really what's normally done?

edit - regarding the gpz, yes, my bike is a 1980 f1.

Alas we are at opposite sides of the country, I'm in Utah.

I think the GPZ stuff might be compatible with the 1980 bike.

JR - thanks. Didn't think the 750s would fit.

Pretty much everything is basically the same between the various 650 and 750 fours, but there are so often just minor changes that will catch you out even though the basic castings are the same.