Looking for speed parts 78-79-ish KZ750H

Check the part numbers for the GPz750 crank and the GPz750 Turbo crank, they are the same.

Somewhere on here there is a dyno chart from a stock 750 twin rated at 54hp by Kawasaki, and it showed 45 hp at the rear wheel, so I'd say the 54 hp crank rating was pretty accurate, so unless you can show some proof of your statement that Kawasaki inflated the hp ratings, then I am going to disagree with you. A 750 four will flat run away from a 750 twin, so I believe the 74 hp figure is reasonably accurate.

With half a point more compression, different carbs (still 34mm), more lift and duration on the cams, the 83-85 GPz750 is rated at 85 hp, and according to the dyno tests of the time that was a reasonably accurate number as well.

If you think 85 hp is the most that is possible out of 5 psi of boost on a 750 four, then the fact that there is (or was anyway) at least two people roadracing KZ750 twins that produced 90+ hp naturally aspirated ought to really get you going.

Thanks for the info steel ill get to looking for cams and pistons right sway, also was there ever a 4 valve head for a 750-4 ?

i dont think kawasaki made any 16 valve motors till the water cooled motors came,it would be cool if something could be adapted though!:evil:

Geeeees you could almost say Too Much Talk !! Just build it, invite us all round to watch it fly!!!
Yeeehaaaaaaaaaaaaaaaaaaa.. :woohoo: :woohoo: :woohoo: :woohoo: :woohoo: :woohoo: :evil:

steell wrote:

Check the part numbers for the GPz750 crank and the GPz750 Turbo crank, they are the same.

Somewhere on here there is a dyno chart from a stock 750 twin rated at 54hp by Kawasaki, and it showed 45 hp at the rear wheel, so I'd say the 54 hp crank rating was pretty accurate, so unless you can show some proof of your statement that Kawasaki inflated the hp ratings, then I am going to disagree with you. A 750 four will flat run away from a 750 twin, so I believe the 74 hp figure is reasonably accurate.

With half a point more compression, different carbs (still 34mm), more lift and duration on the cams, the 83-85 GPz750 is rated at 85 hp, and according to the dyno tests of the time that was a reasonably accurate number as well.



If you think 85 hp is the most that is possible out of 5 psi of boost on a 750 four, then the fact that there is (or was anyway) at least two people roadracing KZ750 twins that produced 90+ hp naturally aspirated ought to really get you going.

I never said that 85 was the most possible, I said that with out getting special cams and a well ported head thats all it should make. It's simple math, the same formulas that turbo system engineers have been using for years. Like i said before it has a potential to make 111HP but it won't come close to that. What other bikes make is irrelevant to this situation. As for the 750 twins, that is not even a comparison. A twin has the potential to make way more power than a four. They have roughly half the pumping losses of a four and about half the frictional losses of a four. Not to mention that the larger bore also unshrouds the valves allowing the head to flow better. 750 twins didn't come from the factory making much power because they were designed for reliability so they have shitty port designs, and conservative camming. It's no surprise to me that they can make 90hp. but I'll also bet they are full of some pretty trick parts that most of us could never afford. Regardless I'm not going to win this argument, no matter what I know you have heard more or seen more kawasaki dyno sheets than me. I'll let you belive what you want, and I guess we'll see how she works when it gets built. Assuming it makes a real 85 hp and the whole unit with rider weighs 700lbs it will go 0-60 in probably the 3 second range if it could hook up well, so it will be a freakin rocket.

on a side note my 250 is going to be run on alcohol and see probably 40+psi and i am hoping for 50 hp it currently make 17 as verified by a dyno jet 150

:laugh: you can't make this stuff up!
to funny :laugh: :laugh: :laugh: :laugh: :laugh:

what do you think I'm making up? Everything I discussed is trivial stuff. simple mechanics and fluid dynamics. Hell most of the stuff could be proven by some simple data analysis.