KZ750 swing arm stretch | 1

I’ve decided to give the KZ a little more length in the rear for looks and function. This is a bunch of work for a slight change but I think it really gives the KZ improved proportions.

Looking through some of the old magazines in the shop I found a Cycle Guide from ’81 with a whole article on the 750’s of the same era. This included wheelbase specs that I wasn’t able to find online. Turns out the KZ had a really short rear compared to the competitors so it validated my idea of giving it a slight stretch that wouldn’t make it look like a stretched Busa. There’s lots of different ways to do this, this is what I came up with:

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Wheel Base Specs in Inches:
CB750F: 59.5 – 60
KZ750: 56 – 57.1
GS750EX: 58 – 59
Seca 750: 57.3
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The old ads are so rad.
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Couple photos of it as is. When sitting on the bike my ass is just infront of the rear axle. With the stretch I want the wheel to be a little bit further behind where the seat will be.

Making the jig brackets. Using L stock I tack them together, square them off on the belt sander, and drill the appropriate holes. Then, when I cut them apart they are exact duplicates of each other.

I have two holes in the rear. One for the stock to get everything lined up and tacked to the table. The second hole is 2″ back. This will put my wheelbase at 58 – 59.1 which is comparable to the other 750’s.

Jig all setup.

Next up, cutting the swing arm.

2 responses to “KZ750 swing arm stretch | 1”

  1. Mike Ashleigh says:

    Nice work! By also moving where the shocks mount to the swingarm back you’ve also effectively lowered the bike and the spring rate a little, but by how much, I dunno. Looks alot more involved than I would attempt.

    I’m currently doing a swingarm and shock swap to my GPz550, so I’m definitely geared more that way, but a ZR550 swingarm should theoretically bolt right in to your kz750 and keep the same axle diameter so you can still run those sweet mags with little trouble. You also get those sick eccentric axle adjusters that I’ll be using on my 900 swingarm swap into my GPz. The ZR swingarm would look a few years newer, but I think its sweet and its probably the lighter solution.

  2. Adam says:

    Thanks Mike. I’m going to be moving the shock mounts so that I actually raise the rear roughly an inch over stock once I get the swing arm stretched.

    I looked at swapping to another swing arm but couldn’t find anything that would fit without modification and yes, I wanted to keep the stock mags. I also didn’t switch to a square aluminum one even though it is stronger and lighter… I just don’t like the look of them.

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