H2/S1/KZ400 40-spoke rear drum on KZ650 20mm axle?

Hey there. I hope to draw on the deep well of this group's experience with mixing-&-matching differnt KZ parts
to other KZ models.

Anybody ever swap the narrower/lighter KZ400/S1/H2 40-spoke rear drum, off it's 17mm axle, and onto the 20mm rearaxle of a KZ650, KZ750, KZ900 or thereabouts?

It'd be a good idea to do so, IMHO, given that there's gotta be a decent 40% weight savings to be gleaned from the swap. I don't have the exact weights measured, but on my FIRST attempt at these two current bike projects (prior to my 2013 house-fire) I had specimens of the KZ400 40-spoke and a KZ650 drum - actually an odd-ball version of which
in the form of the KZ650CSR 48-spoke unit. Now I didn't have a good digital scale on hand, but the smaller drum FELT like it was around HALF the weight of the "full-sized" drum.

(((I also had the conical rear DISC-BRAKE hub from the KZ750B/KZ1000A, and the later 7-bolt rotor type wire-spoke rear disc hub - not the 40-spoke version from the KZ1000LTD (or KZ900LTD ???) but the otherwise identical 48-spoke version of which, from the KZ1000CSR - And THAT'S definitely at LEAST a 50% weight savings. An INCREDIBLE difference between the two. If it weren't for the composite alloy/steel nature of the hub or the EPOXY that holds it together, imho they'd be the "GO-TO" component for a wire-spoke upgrade to a rear disc hub. 'Cause they can take a really small disc back there, too. What a difference though! To think they'd REPLACED the conical hub with such a heavy weight P.O.S. - They MUST'VE had problems, right?)))

If anybody's seen this modification done before, or even if they've just got some insight into the hows & whys & wherewithalls - I'd love to hear from 'em!

Either way: Thanks for your time!


-Sigh.

SoyBoySigh wrote: Hey there. I hope to draw on the deep well of this group's experience with mixing-&-matching differnt KZ parts
to other KZ models.

Anybody ever swap the narrower/lighter KZ400/S1/H2 40-spoke rear drum, off it's 17mm axle, and onto the 20mm rearaxle of a KZ650, KZ750, KZ900 or thereabouts?........................

Ever wonder why the wheels on a KZ400 are different than those on a KZ900?

Think about this –

The KZ400 has 36hp and weighs 386 pounds dry.
The KZ900 has 81hp and weighs 507 pounds dry.

The wheels, shocks, frames, etc., were engineered to meet the requirements of each bike. Do what you think is best, but swapping wheels from a lightweight, low powered bike onto a much heavier, far more powerful bike does not seem like a good idea to me. Ed

650ed wrote:

SoyBoySigh wrote: Hey there. I hope to draw on the deep well of this group's experience with mixing-&-matching differnt KZ parts
to other KZ models.

Anybody ever swap the narrower/lighter KZ400/S1/H2 40-spoke rear drum, off it's 17mm axle, and onto the 20mm rearaxle of a KZ650, KZ750, KZ900 or thereabouts?........................

Ever wonder why the wheels on a KZ400 are different than those on a KZ900?

Think about this –

The KZ400 has 36hp and weighs 386 pounds dry.
The KZ900 has 81hp and weighs 507 pounds dry.

The wheels, shocks, frames, etc., were engineered to meet the requirements of each bike. Do what you think is best, but swapping wheels from a lightweight, low powered bike onto a much heavier, far more powerful bike does not seem like a good idea to me. Ed

+1
Also...
I have laced a KZ400 rear hub to a 2.15 rim and a KZ650 hub to a KZ400 rim.
The Problem with your idea is the axle is smaller and the chain offset is different.

How about a front 18" wheel from a KZ400. Upsizing the axle bearings to a Z1-KZ900 front axle. (drawing a blank on axle diameter?)
This way an 18" drag slick can be used for an old vintage drag or street bike. Plus this one has double sided rotor bolt holes for dual disc.
Point is, that I might sell that wheel easier with a higher price to the bigger bike person. Than selling it for a stock kz400.
I have an old kz900 hub to compare the 2 somewhere.
I built a 19" years ago with Buchannon SS spokes. Wish now it was the 18" size. already lowered the front fender holes.
Opinions??