Crankshaft

im sitting on my personal dyno right now,its called my ass:whistle: the 900 crank will not make more horsepower,but it will get your motor to the rpm range where its making horsepower faster than heavier crankshaft as long as you dont have too much tire for the lighter crankshaft to overcome.once you get it moving down the road the weight of the heavier cranshaft makes it easier to maintain momentum.on a turbo motor my experiance has been heavier cranks tend to work better to overcome the load of spinning the turbo.ive only built one turbo motor but that was my personal experience i will be starting my next turbo as soon as i finish current project now that i have nothing else to do for the rest of my life! :woohoo: Lorcan,or Fastest Z1 might have something to add about the turbo crankshafts.goodluck,happy wrenching!

The lighter crank affords much quicker rev up and rev down. How noticable this is when connected to the rest of the drive train depends a lot on the drive train. It makes a huge difference in shift speed...

=Duck

Lots of people pay a lot of money to lighten their crank (check out faliconcranks.com), so if you can find a lighter one (900 crank) thats a "bolt on" (and it most definatly is ), and it fits your riding style better, go for it.
Scott

The trade-off is faster acceleration versus more torque. On the street a 77-78 KZ1000 engine is a smoother and better cruising engine.

The Z1 engines rev quicker, but tend to have more vibration - and a much peakier powerband.

The Z1 engines are noticably quicker revving.

The Z1 cranks are the lightest
The Mk II cranks are in the middle
The 77-78 (and some 79) cranks the heaviest

On the drag strip you get two different camps of engine builders - those who want the faster revving engine, and those how want the extra torque off the line - both work - just different approaches.

and of course jeff a has couple turbos also.

cgi.ebay.com/ebaymotors/KAWASAKI-Z1-KZ90...temZ4617083739QQrdZ1

just incase anyone was looking!

bought it, thanks!!!!!!! this is going into my '77 kz1000 engine and all going into my 650 frame!!!!!!!

gotta love it!!!!!!

Awesome deal on that crank! $10!!! I'm afraid my MKII is going to need a crank due to an unfortunate flywheel incident:( It eas welded and everything too! Now I don't know what type to get. It sounds like the 900 or another MKII crank is the best way to go. How many teeth (cam chain) does the MKII crank have? Also, are there any mods necessary for a 900 installation in a MKII engine? (I'm guessing cam chain and cam sprockets?) Any mods (clearances, measurements, machining) needed when replacing a crank with the same type? Any advice is greatly appreciated. I'm lost and counting on you guys as usual!
Thanks!

markII crank has 16 teeth i do believe 900/1000 cranks have 15 teeth.dont scrap that crank it might still be salvagable.

wireman is correct, the mkII does have 16 teeth on them the kz's have 15. i did alot of checking. oldkawman has i think one or two mkII cranks on his site for sale.

good luck

Now,could u imagine knife edging the crank (lighting).U need the bigger tire for more traction with the increased h.p. Just go up a couple of teeth on the rear spocket,my loose a couple of m.p.h,but a man can add alittle more valve spring pressure to gain another 1000rpm, theres your m.p.h.back. Not that much harder on cams.I like increasing back spocket size,longer radious.A drop in counter spocket size increases chain bind so to speak. More stres on counter shaft. Remenber, r.p.m x gears = m.p.h. Go get that 900 crank. Oldkawman might have one.

OK, here's a new one on me. Has anyone ever heard of converting a 77-78 crank to a MKII type? This item "has had a big center section put in it". When I asked the seller he said, "it was a 1000 crank which was converted over to basically a mark 2". He told me it has 16 teeth, but do the counter weights look like MKII or 77'78?
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&i...name=ADME:L:RTQ:US:1