1979 Honda XL500S – Frame 2

By southernscoot

1979 Honda XL500S – Frame 2

While sorting out the tank the seat has now become the next main focus because of where the rear of the tank will mount. There are plenty of cafe racer style seats available online, at reasonable cost but they might not necessarily fit. Some have the seat dimensions and bracket locations marked with metric or imperial measurements and look quite good in a bolt on, ready to go way. The frame was going to have to be modified to take a new seat and other builders I had researched were using pre-made rear frame hoops that came in various sizes and metals and were then welded onto the existing frame to support the seat.

After watching a couple of YouTube videos the procedure looked relatively simple enough and involved deciding where to cut the frame and welding on the correct length hoop. I decided to have the rear of the hoop in line with the centre of the rear wheel to give it the Cafe look. The rear of the stock frame stuck up in the air quite a lot and it was going to be tricky to get the new rear frame as flat as possible to get the seat bottom to line up with the bottom of the tank.

The original twin shock mounting points were the obvious position to cut the rear sub frame off and I had seen a similar XL500 build on a forum where the mounting points were shifted for this reason. I didn’t want to do too much structurally to the frame as this was my first build and my welding isn’t the greatest but something has to be done. While thinking about how I could do this I noticed that the existing rear frame hoop might be able to be turned upside down and used as the new rear hoop. This would achieve three things:

  1. The hoop is already the correct width and should weld straight back on, no problem.
  2. Depending on where I cut the rear frame off, the hoop could be the correct length.
  3. The rear hoop upside down wouldn’t make it level but would be better than having to shift the shock mounting points.

After measuring everything twice I cut off the rear section just behind the shock mounting points where extra plates had been welded for supporting the rear sub frame. I eventually got a mate to turn down a couple of 25mm steel bolts on his lathe so that they would fit into the frame. Attaching the old hoop was pretty straight forward and it has a bracket on it that I may be able to re-purpose for the seat to attach to.

Previously I had installed the new carburettor and re-jetted it, as per the Mikuni website and then installed the handlebars for the new clutch and throttle assemblies as I got it ready to start. I also replaced a few parts on the engine and had got the wiring sorted out enough to have good spark and an earth wire I could use for a kill switch by grounding on the frame. After a quick search around the workshop, I found a plastic, litre bottle with a nozzle, that a temporary fuel hose would fit on and decided to try starting it. There is no muffler or seat but I was pretty keen to see if it would actually run.

 

Somehow I had forgotten how to start the engine properly, but now that it actually goes, I can carry on with the project as time permits.