Z2 750 crank (Bossie the Kaw)

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30 Nov 2016 14:23 #749193 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
Just ordered my 903 crank. Been watching it for a while. There's a 1075 kit I have my eye on but it's the old style cast Wiseco pistons. I'll make an offer and if it's accepted, I'll buy it. I figure I can sell the 750 Z2 crank and my 1015 pistons and make some money on the deal. If nothing else, the bike should be quicker with higher compression. We'll see. :whistle:
Steve

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30 Nov 2016 14:51 #749195 by KZB2 650
Replied by KZB2 650 on topic Z2 750 crank (Bossie the Kaw)
Just in time for Christmas...... betting your gonna feel a big difference in power... am looking forward to hearing about it.

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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30 Nov 2016 15:00 #749196 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
It took a while to gather the parts needed for my valve job one by one. The original Wiseco's were cast but they don't sell them anymore. The rings are the same so if I do get the 1075, I'll get new rings to go with them. Gives me something to look forward to. B)
Steve

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01 Dec 2016 05:55 #749221 by 531blackbanshee
Replied by 531blackbanshee on topic Z2 750 crank (Bossie the Kaw)
your going to think you got hit in the ass by a train the first time you crack the throttle on your rebuild :evil:

leon

skiatook,oklahoma 1980 z1r,1978 kz 1000 z1r x 3,
1976 kz 900 x 3
i make what i can,and save the rest!

billybiltit.blogspot.com/

www.kzrider.com/forum/5-chassis/325862-triple-tree-custom-work

kzrider.com/forum/5-chassis/294594-frame-bracing?limitstart=0
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01 Dec 2016 06:02 #749222 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
:lol: :lol: :lol: I hope so. Been squeezing as much juice out of this thing as I could get.I always knew something was missing. :whistle:
Steve

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01 Dec 2016 06:10 #749224 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
Funny thing about it though, when I ran into Miller on his Honda Davidson in 87, I pulled on him when before he would walk away from me. He said "you're learning." That was with new cams and stock carbs. Obviously the lighter crank made a difference even with the loss in compression. :unsure:
Steve

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01 Dec 2016 06:28 #749230 by 531blackbanshee
Replied by 531blackbanshee on topic Z2 750 crank (Bossie the Kaw)
lighter cranks spin faster.

but compression makes torque and horsepower! :evil:

plus you'll be gaining back some stroke which will be more torque at the expense of less revs.

leon

skiatook,oklahoma 1980 z1r,1978 kz 1000 z1r x 3,
1976 kz 900 x 3
i make what i can,and save the rest!

billybiltit.blogspot.com/

www.kzrider.com/forum/5-chassis/325862-triple-tree-custom-work

kzrider.com/forum/5-chassis/294594-frame-bracing?limitstart=0

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01 Dec 2016 07:31 #749233 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
YUP. A added bonus is if I left this crank in the shop, it would have burned with all the rest of my parts and had been stolen for scrap. :angry: It's valuable and can be sold for $$$ :woohoo: . I'm tempted to tear into it as soon as it arrives but I've waited this long, might as well get the other goodies I want as well. B)
Steve

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03 Dec 2016 15:24 #749386 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
Got my crank. Better than I'd hoped. I'll have Jeff weld it and put it in. Might just do that first then go with a bigger bore later. :woohoo:
Steve

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04 Dec 2016 07:14 #749409 by joe k
Replied by joe k on topic Z2 750 crank (Bossie the Kaw)
Happy to here that you have finally found the crank what you had wanted but before you send it out for welding don't omit to check how true and also the condition crank side thrust bearings are as these 1973 to1978 cranks 15 pin shafts are not as strong due to smaller bearing pin size as against the 1978 to 1980 shafts and will not rev out the same as Z2 . I myself if building this motor would have stayed with the Z2 and raised the comp to 10 to 1 or better still got a good J crank an changed the centerpin to a 16 pin mark style.

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04 Dec 2016 14:32 - 04 Dec 2016 14:33 #749436 by SWest
Replied by SWest on topic Z2 750 crank (Bossie the Kaw)
In 40 years I have never had a issue with a 903 crank. In 78 I installed a 10.25/1 1015 kit and beat the hell out of the bike. Never had the crank welded. The 750 Z2 crank is identical to the 903 except the rods and possably the throws. :unsure: In 87 when I did it not much was known about them. I had it welded figuring I'd go with a bigger kit sometime. Since then I've knocked the snot out of it with no issues. From what I've read the early KZ 1000 cranks were just as bullet proof just heavier to reduce vibration. As I understand it the late cranks have thrust bearing issues and have been discussed here recently. I will have Jeff check the crank and tack weld the pins. I will take a closer look at the thrust bearings.
Steve
Last edit: 04 Dec 2016 14:33 by SWest.

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05 Dec 2016 21:44 #749606 by missionkz
Replied by missionkz on topic Z2 750 crank (Bossie the Kaw)
Does the 750 crank have the same stroke as the 900?

Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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