1979 kz650b swingarm swap?

I have recently bought a 1979 kz650, and i want to extend the swing arm. I noticed in the forum that someone had said that a kz900/kz1000 swingarm would be a direct swap? can anyone help with this? i have the oppotunity to buy a 1978 kz1000 swingarm and would appreciate the help. Is there somewhere where you can get the technical specs on these swingarms? measurements etc.?

Not sure about 79 650 but is not a direct swap on 78 650 and I would expect them to be the same - I just did a swap with a 78 650 using a 77 KZ1000 arm. After taking the end seals of, the 77 KZ1000 arm was 9 inches wide at the pivot, exactly 5/32 wider than my KZ650 arm at the same area - you have to grind down the arm or the frame to make it fit. I trimmed the arm and it went very easy - lots of stuff here in the archives, is good to do a search and soak it all up, I will be glad to answer any questions that you might still have. Important to keep the ends square to the pivot and go slow and only trim exactly what you need off and no more

You also have to take out or push the needle bearing out of the way into the pivot tube farther before trimming, (wash it all woth solvent copiously later if you leave it in - but I would recommend taking it out first), and trim down the bearing inner tube the same amount, and depending on which year KZ1000 donor arm and pivot bolt you used, you may have to get a later KZ1000 pivot bolt with a double bearing machined surface to accomodate the further pushed in needle bearing. The 77 KZ1000 arm pivot bolt that came with my arm only had one row of needle bearings and a limited area machined surface, I believe the 78 and later used two rows

kzrider.com/component/option,com_joomlab...ew/id,24576/catid,5/

Also, remember that the rear axle is larger diameter on the KZ1000 and your Kz650 wheel will no longer fit the new kZ1000 arm axle-wise - you will need new larger bearings and axle, or use a KZ1000 rear wheel set up like I did. Same for brake caliper axle hole if you are disc. Will also have to check your brake stay arm length. I basically went with a whole KZ1000 rear wheel and caliper brake set up so it all went in the KZ1000 arm just fine

The KZ1000 arm is a bit beefier, about 0.1 diameter larger tubular sections and about 1 1/2 inch longer than the 650 arm. not sure if it buys a whole lot for the bike performance, but it basically allowed me to go to KZ1000 rear disc set up so it was an enabler for me and a good project

danB, you got any pics of your finished project?

No pictures yet, just getting started on it. Was a daily rider 650 until it got a little tired and I thought would be fun project to restore it back up as a little higher performance street racer. It is all stripped down, just starting to mock it back up and fit everything, collecting parts from EBay , etc. Will be cafe race type 650 frame with 750 engine and 810 kit, all discs and wire wheels, lowered a bit, pods, Dyna, etc. Longer term project I am sure. Have the engine and most parts in hand now. Would like to get it mocked up and pieces sent off to powdercoating and such in next couple months. I have a KZ1000 to ride on the side, so am in no rush on the 650 project