Fork adaptation

I've spent alot of time thinking abount upgrading the forks on my 78 KZ650B1. But there are lots of issues with stem length, size, bearing fittment etc. when taking a front end from another bike. Not to mention getting the 'bits' to hang off the top triple in a safe and secure manner.

I haven't heard this idea discussed. Say, I take a 2000 GSXR fork (non-inverted variety) and get my triple (top and bottom) milled out to fit the slightly larger fork tube. I believe mine is 39mm in diameter and the gsxr is 41mm. Now I know those numbers may not be right...but would the theory work. And likewise if my fork is 41mm and I go to a 39mm fork tube (a hypothetical) can a machine shop fit appropriate shims in place? It would seem to be a fairly simple and cheap way of getting a near new fork set up with minimal fuss. (Of course getting the brakes and wheel to run properly is another for a later thread.

I look forward to hearing from this forum' s collective wisdom.

Ciao
Scott

Post edited by: zippywhoosh, at: 2005/12/05 01:27

The 79 650 fork is 36mm diameter
I gave this some thought in the past, and decided that I just would not feel safe milling it out over 1mm larger.

You have to keep in mind that newer wheels are usually wider and need wider fork spacing just to fit between the forks, so replacing the stem or bearings usually is the easiest way to go anyway.

If you're going to put on a modern fork, you should go ahead and change the whole front end with wheel and brakes and fender and steering head and the whole bit. Once you get the stem and bearings sussed out, it's pretty straight forward.

I was able to keep my LTD triple because I switched to another 36mm fork from a 1982 GPz 750. I did have to use different brake calipers and fender because of geometry changes, but the wheel is the same.

You might consider keeping your stock fork and upgrading it with some progressive springs and maybe adapting in some cartridge emulators... Both items I plan to do at some point.