Z2 750 crank (Bossie the Kaw)

Yes, this is possible, using a short stroke z400J crank with a wiseco "610cc " kit bored out 550 block, same pin size. The rods and forged one piece crank are bulletproof but I think there are factors limiting rpm on any 8 valve ,

Short stroke would lose some bottom end tourque, something the big old kz were good at, the later GPz more power but a lot more 'cammy'.

Good luck on the build Steve, you have most of the bits and the vision for something really nice there.

Its like a 396/427 chevy versus a 454 chevy.The 427 and 454 have the same bore,but the 427 uses the same stroke as 366/396 which makes it a real riot to drive . :woohoo:

PLUMMEN wrote: Its like a 396/427 chevy versus a 454 chevy.The 427 and 454 have the same bore,but the 427 uses the same stroke as 366/396 which makes it a real riot to drive . :woohoo:

Was thinking the same thing ..... the 383 Chevy and the 302 Z28 motor too.

You've got to be kidding. The 4 valve piston was Z1E's fault. Like I said, it set me back two weeks. They didn't have just one piston to send me like now. It will cost me $125 for a new piston, figure in gaskets and we're looking at $200. As it is, I'm burning up rear tires. Makes it tough to save the money and keep up with what the bike needs normally.
I'll do it.
Steve

BTW, I have 1X Andrews cams in the bike. They're supposed to improve low end. Blakeem put up the specs. I sent him.
Steve

Per Dave Marsden:

THE Z2 WAS IDENTICAL TO THE LARGER BIKE IN DESIGN EXCEPT FOR THE DISPLACEMENT OF JUST 746 CC AND SMALLER 26MM CARBS.
IT WAS ONLY OFFERED IN THE BROWN AND ORANGE COLOUR OPTION FOR THAT YEAR.
ENGINEER INAMURA DECIDED THAT SIMPLY REDUCING THE BORE SIZE OF THE Z1 WAS NOT GOOD ENOUGH. INSTEAD KAWASAKI CHANGED THE BORE AND THE STROKE TO 64MM X 58MM. THIS CHANGE REQUIRED A DIFFERENT CRANKSHAFT, CYLINDERS, PISTONS, PINS AND RINGS. THE REST OF THE MOTOR REMAINED THE SAME.

Good Fortune!

Patton wrote: THE Z2 WAS IDENTICAL TO THE LARGER BIKE IN DESIGN EXCEPT FOR THE DISPLACEMENT OF JUST 746 CC .... THIS CHANGE REQUIRED A DIFFERENT CRANKSHAFT, CYLINDERS, PISTONS, PINS AND RINGS. THE REST OF THE MOTOR REMAINED THE SAME.

Hmm, that still doesn't answer the question. The mention of different "cylinders" could imply a different deck height, but it could also just be that they changed the casting to fit smaller sleeves.

Based on my impression that the Z2 only existed because of the law limiting motorcycles to 750cc, and that the Z2 was a Z1 with minimal modifications to meet this legal requirement, it does seem possible that they bid not bother to change the deck height of the Z2 from the Z1. This may not have provided the optimal stroke to connecting rod ratio, but it would certainly make the conversion easier.

Here is another angle. Can anyone figure out if the Z2 shares the same cam chain as the Z1 (same number of links)? If the deck height were the same, wouldn't the cam chain length also be the same?

YES.
Steve

My camera is a battery hog. I tried to take some pics of the blocks with my bike cam.
Steve

The one on the bike says 1015. I'm charging the cam. I'll get another on in the sun in a few minutes.
Steve

May not be useful but I have a standard set of 1015s at home as paper weights. If you want to send back the Pistons you bought and use mine let me know. Would save you some serious coin. I def want to see this crank. Maybe this bully of yours (I'm not taking sides but it seems excessive) will drop Ya 100 bucks to tear down the bike to see the crank. Put his money where his mouth is? I know if I was so sure, I'd do it. But I don't know anything about this stuff.

Thanks for the offer. I have a set of stock 1015's in the bike now. I will buy another 10.25/1 piston as I said in time. I'm in no hurry.
As for the bully, they are all cowards. They never put up or shut up.
Steve