KZ650 Swing arm converting bushings to bearings

Hey, any of you early (77-78) KZ650 owners know of a way to replace the OEM bronze swing arm bushings with roller needle bearings (without spending hundreds of $$$$ ?

Does the Z1 / KZ900 kit offered by Z1 ent. fit the KZ650?

Thanks!

Why bother? The bushings work great as long as you lube them on a regular basis. Ed

What about installing a 750E swingarm? You can get one for cheap on ebay.

Thanks for the advice. If this was my bike, I would, at minimum, swap the arm for a uni-track and have twin shock mounts welded on, or go with a single shock set up. Something other than messing with the worn out parts I have to work with now!

But this is a "customer's" bike that I'm resurrecting from a storage and maintenance neglect nightmare. You guys have to see what kind of rectifier this bike has on it! I'll post some pictures later in the projects section. The original swing arm bushings and center sleeve were so worn that the rear wheel has about 1/4" of sideways movement. While the bushings are still available, the sleeve is obsolete unless you can find a NOS one (they are out there, but are generally over $100 on evil-bay).

Given the fact that bushings generally wear faster than bearings, and for how much it would cost to replace all the stock parts, I would like to put bearings in. Oh - the owner wasn't even aware there is a grease fitting on the swing arm, so I won't expect regular maintenance to be done...yeah, bearings will likely be wiser on this one...

If the owner is so dopey that he doesn't know the swingarm has a grease fitting maybe you should hardtail the swingarm and tell him it is permanently lubed. :laugh: :laugh: :laugh: Ed

The design of the bushing setup with the sleeve was pretty poor, so I don't blame anyone for wanting to get rid of the bushings for needle bearings. The way the grease zerk works on the 1977 model with the bushings is grease goes in through the zerk, then travels several inches via worm passages in the sleeve to the bushings. This is the concept anyway. Problem is the worm passages get clogged with old grease almost right away then you can pump all day through the zerk and no grease goes anywhere. Good reason they got rid of that system quickly, one of the worst designs ever.

RonKZ650 wrote: ...... Problem is the worm passages get clogged with old grease almost right away then you can pump all day through the zerk and no grease goes anywhere. ......

I've never had that problem with mine and I've had the bike for 39 years, but I lube the swing arm every 1,000 miles. Grease always flows freely through the worm passages. on mine. I guess if it is neglected the grease could coagulate, but I have no idea how long that would take. One thing I would say is that the worm passages on the original swing arm sleeves are more widely spaced and are more laterally oriented than I have seen on some replacement sleeves (see images below), so that may have an effect. To me, the replacement sleeves look like they could clog up easier than the originals. Ed

ORIGINAL SLEEVE


REPLACEMENT SLEEVE

The needle bearings would make a nice upgrade. Without regular greasing, they would be harder to replace.
Steve

650ed wrote:

RonKZ650 wrote: ..

REPLACEMENT SLEEVE

Attachment 00003b-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-20-21-22.jpg not found

Hey, this is exactly the solution I need! If I can buy this "replacement" sleeve - the grooves being closer together will work (acceptably) with the needle bearings - and I won't have to machine my own sleeve! Where can I get one of these????

Kray-Z wrote:

650ed wrote:

RonKZ650 wrote: ..

REPLACEMENT SLEEVE

Attachment 00003b-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-20-21-22.jpg not found

Hey, this is exactly the solution I need! If I can buy this "replacement" sleeve - the grooves being closer together will work (acceptably) with the needle bearings - and I won't have to machine my own sleeve! Where can I get one of these????

Never mind - just found it and it is over $120 CAN.! Looks like I'm back in the machine shop on this one!!!!

So, here is what I've come up with:

I ordered 4 of the needle roller bearings for a later model KZ650 swing arm from Z1E. I measured everything and then cut the ends off the old bronze swing arm bushings, as they are required for shimming the swing arm end play. I parted them off on a lathe using a parting tool, leaving 0.100" to protrude into the swing arm tube. See [strike]upper left in photo[/strike] sorry - mid - right!!!:




Then back to the lathe, I turned 2 inner bearing races from tool steel, with 0.001" of total radial clearance on the roller bearings and the swing arm spindle. I still have to cut the old sleeve down, but it was 2 a.m. when I turned the lights off in the shop last night!





The assembly (with liberal amounts of bearing grease) goes like this:





The new Z1E needle bearings get pressed (2 a side) into the swing arm in place of the old bushings. There is an air gap of 0.125" between them in the swing arm. The old, worn out center sleeve is cut to length (the amount cut off = the length of the 2 new inner bearing races I made) and inserted in the swing arm as a spacer between the new inner bearing races to keep them in place. The cut off ends of the old bushings then are pressed into the swing arm as end spacers



Then the old dust / grease seals placed over them, then installed in the frame.

Total parts cost is under $20! (don't ask about how long it took to make the parts, please!)

Done, and it worked out well.

The swing arm pivot rotates easily and I have no measureable radial or end play.

On to the next problem - rebuilding the rear master cylinder!