Why are there two kz1000 motors?

Jeff.Saunders wrote:

9am53 wrote:

Z1 - so the original Z1 had a lighter crank with the lighter flywheels, how would that affect performance compared to the heavier flywheels? I am guessing the heavier ones will carry a broader torque curve whereas the 900 would seem spritelier but youd need to keep the revs up. is that right?

Yes, the Z1 engines rev very quick, but lack the torque of the 1000's. It's not that they are better or worse, each has advantages and disadvantages.

If you are drag racing, there's two distinct camps - those who want torque off the line, and those who want the revs at top-end...

Don't confuse torque with flywheel enertia.

Enertia Definition

1)Physics. The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force.

2)Resistance or disinclination to motion, action, or change.

All things given as equal, flow, port size, bore size, carb, cam, gearing, weight of bike, etc.....between two bikes. The motor will produce the same amount of torque. Torque & RPM being the components of HP.

So this isn't really a matter of torque but one of enertia.

A light crank will rev easier than a heavy crank. But, by the same notion, the heavy crank is more resistant to being pulled down in rotational speed when the load is placed on the engine [leaving the line].

That is very different than the torque produced by the design of the engine.

Things that work for you in one respect can work against you in another respect. There are always compromises to be considered.

Larry C

Jeff.Saunders wrote:

front

I'm thinking TRA primary clutch....Polaris Secondary....4 wheels....oh yea!

I blew up the pics. That looks like an OEM crankcase casting. I sure don't see any welds to indicate home brewed.

Probably just another example of how Kawasaki was ahead of their time with another innovation.

Larrycaven - so the heavier flywheel makes it slower off the line, but likely when I go up a hill the heavier crank will keep my revs from dropping as dramatically right?

I get how the cranks mass could effect regular driveability, but how could a heavier crank be better in a drag race? or does the heavier crank actually add torque like I surmised earlier?

I hope these aren't dumb, I'm just a very interested newb!

Cheers!

The heavier crank launches easier, especially with a big dragrace tire, because it keeps the engine from wanting to bog as badly when the clutch engages. The extra weight of the spinning crankshaft helps it keep the rpm up without the need to slip the clutch so much. Once in-motion, though, the lighter rotational mass will accelerate more quickly, due to less weight needing to be accelerated.

thanks, makes a lot of sense!

Jeff.Saunders wrote:

Side shot

Cool,MKll motor.Canadian / European castings too, no smog ports...

RacerZ wrote:

Jack wrote:

Had one of those Falicon supercranks in a 1200cc.Z1 Instant revs - at the time I only weighed 160 lbs. and it worked just fine...until the #3 rod broke at the top of third gear.

You don't go on to say whether or not it was a MKII Crank like the one pictured, and whether or not you had the Main Bearing Crank Cap supported. Z1 Crank has a 15T Pin, MKII has 16T Pin (Stronger) for those that may not know.[/quote]

Nope, it was definitely a 15 tooth Z1 crank and supported with a main bearing centre plate.Like I said, I was light and the bike was light.Worked good until it broke...

Hi Jack, that strange 1000 motor was European. The pictures came from a crazy Swede... ...so probably Nordic or German market only.

The MK II valve cover and engine covers date it as 79 or 80 vintage. I do have some additional pictures of the engine, but nothing very interesting (other than confirming the cases have to be OEM).

I'm back with an adition to this thread...looking at my manual, the kz1000J bike (not motor) has 102 hp, whereas my LTD has only 92...whats the deal there? the bikes seem to have the same carbs, what gives the J so much more power?

the camshafts and some internal pieces in the carbs were different

Thanks

i'm going to have to agree with anything jeff says..been dealing with him for years and he's never steered me wrong..