1979 Honda XL500S – update 1
I had read on one of the thumper forums that replacing the XL swingarm with the FT one was possible with not too much hassle. The FT is wider at the mounting point and longer with the bottom shock mounts a little further back than the XL one. After a bit of measuring and cutting then a bit of grinding the FT swingarm fitted into the frame fine. Everything looks fine but the new shock mounting points, are further back with the longer swingarm. Because of this I have lost a bit of rear suspension travel but probably wont notice it too much as I’m not planning on doing any serious off road riding.
One of the footpeg bolts was broken off in the frame so that proved to be fun getting it out but after heating it with a torch and using a large pair of vice grips it eventually came out. The new fork trees and the frame had to be fitted to make sure that everything was going to work, so when the frame came back from the engineer it was going to be pretty straight forward to get the forks installed and get a rolling frame set up.
By using the All Balls chart and fork conversion tables – here – and physically measuring the stem I was able to get a rough idea if the whole triple tree was ever going to work or not. The original XL forks were 35mm diameter and the CBR ones are 37mm so with the FT being close, it was just a matter of seeing which upper and lowers would need changed and how the stem would have to be adapted.
forks ID OD Width ID OD Width
37 Honda CBR600 1989 26 47 15 99-3520-5 30 55 17 99-3519-5
35 Honda XL500S 1979 26 48.5 15 99-3511-5 27 48.5 18 99-3524-5
37 Honda XR250R 1981 26 48.5 15 99-3511-5 26 48.5 15 99-3511-5
37 Honda XR250R 1982 26 48.5 15 99-3511-5 26 48.5 15 99-3511-5
37 Honda XL500R 1982 26 48.5 15 99-3511-5 26 48.5 15 99-3511-5
37 Honda FT500 1982 26 48.5 15 99-3511-5 30 50 14.25 99-3512-5
The new fork tree is on the left, the XL one on the right, in the middle picture below:
Getting a rolling frame was important as the 500 cc engine is quite heavy and a bit awkward to move around and to work on. Also getting to this point has involved a fair bit of time and money so It would be good if the engine will start and run. While all this was coming together I had been looking at petrol tanks on ebay and trade me that may fit the frame and look better than the factory one (that also didn’t have a fuel cap or tap)
Finally a bike is starting to take shape.