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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 10:49 #667650

  • Tyrell Corp
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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.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 10:58 #667652

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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:
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 11:04 #667653

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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. ;)
1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 12:49 #667661

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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
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 12:56 #667663

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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
Z1b1000 1975 Z1b
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 13:39 #667669

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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! :)
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 14:11 #667674

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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?
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 14:48 #667679

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YES.
Steve
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 15:26 #667685

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



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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 15:30 #667686

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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

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Last edit: by SWest.

Z2 750 crank (Bossie the Kaw) 12 Apr 2015 15:46 #667687

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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.
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Z2 750 crank (Bossie the Kaw) 12 Apr 2015 16:12 #667690

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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
Z1b1000 1975 Z1b
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