KZ400 / KZ440 forks

The fork upper tubes on my '77 KZ400 are pretty corroded & binding, so I got a set of legs from an '81 KZ440 which kz400.com claims are interchangeable. They indeed have the same diameter, but fully extended, the KZ440 legs are 32" from top to bottom, where as the ones on my bike are at least 2" longer. Which one is right ?

I can believe that mine existing ones are non-standard, since they have much more of the upper leg exposed at rest (12"), and more space between the fender and the frame, than I see in every picture of these bikes. The welding around the headtube looks original, so if someone tried to chopper it in the past, they didn't change the angle.

The other problem is that the lower tubes are different - mine have the caliper mounts in front of the leg, the new ones have it behind. Not a big deal anyhow since I need a new caliper that doesn't have the bleeder screw broken off. But, will the existing axle work safely ? My left tube has a separate clamp piece at the bottom to hold the axle and the new one just has a hole. Otherwise, can I mix & match the upper & lower tubes to get something that works ?

Thanks !

Answer is the kz440 forks won't work unless you change the wheel, speedo, disc, and caliper along with it. The 440 & 400 have different discs of different thickness and offset, changing just the caliper won't work. The axle shoulders on the fork are in different positions between the two - same spacing, but different offset from centerline, so the wheel won't be centered.

Thankfully, the upper tubes are interchangeable between the two. Unfortunately, my right lower tube is out of round so that it binds with any upper tube other than the one that wore to match it. Aargh !

Both forks have a damper rod with a perfectly round top with a 10mm round hole - nothing for a socket to grip. Grinding a 1/2" steel rod to end in a pyramid and jamming it down the hole grips well enough. Which I hope it should since it looks just like the $30 Kawasaki special tool. The wood & aluminum versions I tried first just got rounded off and slipped.

3 of the 4 Allen bolts in this project came out with a couple whacks of a manual impact driver. One the other one it chewed up the bolt head. The two screw extractors we tried broke without budging it and we finally drilled the head off. The weird thing was the remaining bit of the bolt wasn't even finger tight in the damper rod.

I made my damper rod tool by hammering the end of a square pipe into the pyramid shape - no way in hell I was spending $50CDN on a socket

Hope everything works out

Thanks for pointing out the insufficient info on kz400.com.

his is the original text on the site:

"Forks can be exchanged as all are same diameter but as model progressed it went from drum to disc with a change in the bottom fork leg, so you will need to either swoop stanchans or fit correct wheel assy."

I have now changed it to:

"Forks can be exchanged as all are same diameter but as model progressed it went from drum to disc with a change in the bottom fork leg. And the bottom fork leg also changed between the different disc brake models, so you will need to either swoop stanchans or fit correct wheel assy. Also the lenght of the fork tubes will vary between the different models."

kz400.com/ModelidentificationFrameset.html

ok fast math. a stock 400's forks are 30 inches. 440ltds are 32 inches and yours are about 34ish. a stock neck 400 with 4-5 inch over forks has to look a bit wierd. but if it was done in the 70's im sure he was not the only 400 chopper out there.
if you want the 440 stuff you have to change the wheel, brake, speedo drive and everything.

flht1997, you are right about that. His fork tubes are not the stock KZ400 tubes if they are 34 inches.

Yes, the forks that came with the bike are not stock. Switching back to the stock length looks more natural, plus it's a more comfortable height for short me.

To be precise, I think the switch in lower leg was in '78. Earlier has the caliper in front of the leg, later has the caliper behind it.