Z1 pistons

I've been in love with the kz for 40 years, and have always wanted one. A few months back I came apon a 1974 z1 that had a big bore kit put in it in the late 80's, than was promptly rode into the back of a car. The guy took the z1 home and stuck it in his shed, where it say for 25 years. We'll I found it. Bought it. And now I finally have my kz I've wanted since I first heard that kerker on my neibors bike when I was a kid. I fitted a gsxr 750 front end, and gsxr600 monoshock swingarm in the rear. And am now trying to sort the engine out. The engine spun over fine. But it sat for so long, I figured I should get a good look at it. So, I took the head and the cylinder bores off the case. But the pistons are not what I expected. I know it's a "semi-hemi" head, but the piston dome resembles a volcano waiting to bust. I have worked on several hemi car engines, with dome pistons,but never a motorcycle engine, and not one with such a large dome. My question is this. Why is piston dome so misshaped? I assume to increase compression. And if so I have. Stock cams and carbs. Kind of a waste if high compression?

No it's not. Measure the bore. It should be 66 mm. If it's 70 mm, it has a 1015 big bore kit in it. It would work with the stock cams but if the PO went to that much trouble, it probably has the cams to go with it. I have 2 70 mm cast pistons for my big bore done in 78 in good shape. They aren't made anymore so I had to buy the forged billet pistons for my bike because one piston was damaged. I bought KZ 1000 barrels and they barely fit. Now I can go out a lot more with out overheating. That was the problem with the 903 barrels. I still have them.
Steve

Have you thought about trading the z1 to somebody for a 76 900 or a 77-80 kz1000 to build?
Z1s are pretty rare bikes,and are worth a lot more restored than a chopped up kz series bike.
Just saying

I bought this Z1 new. I know what they're worth. The KZ's have parts that are interchangeable with the Z1. I'll give it to my children when I can't ride anymore. I hate it when I see a chopped up one.




Steve

That pic was when I started to put it back on the road. Here it is now.

I believe plummen was talking to the topic starter swest.

And yes cut up a 1980 ltd, they seem to be giving them away

Yeah,he beat me to my original post,
.I was referring to o.p wanting to do suspension swap on his z1.

Keep your Paws off of My 80 LTD, floivanus, I don't want it cut up :evil: :evil:


Pete

Not your's pete :woohoo: just one or two of the FOUR I've somehow come upon...

Two were free. Hence the giving them away comment. They just beg for lower bars and a real gas tank