Sunday, 1 January 2017

The XS Triple Sidecar - cleaning the roundslide carbs, brake rebuild and filling some holes in the tub

Having noticed *duh* that the year is coming to an end and I haven't quite finished the sidecar over the Christmas holidays (not that I thought I would), it was well about time to get my hands dirty and get some more stuff done on it.

First thing was to dive into the Mikuni VM36es, which came off a Polaris snowmobile. The jetting is a bit hefty for a 4-stroke at #50 pilots and #230 mains, but the slide cut out is ok and both needle and needle are just slightly richer than on the 4-stroke VM38-9s I run on my TR1 and won't do harm as the XS will mostly be run part throttle (it's a sidecar not a racebike) and from my first XS-sidecar I am well aware that a bit of extra cooling can't do harm.

So that's what I started with. They were very clean on the inside, but rather filthy on the outside. But more importantly they came with and without a few things, which makes using OEM carbs so annoying at times:
  1. They come with cable chokes.
  2. Except for a slightly weird retainer clip for the throttle cable they are perfectly standard VMs on the inside.
  3. They come with rubberised float needles.
  4. They came with 3-way junction boxes for both throttle and choke. 
Now onto the junction box. This is obviously not meant to be taken apart as I found out and so I ordered a 3-way junction box from Amal (244/2080), which is meant for both Triumph and BSA triples.

Unfortunately the cables are glued into the box and I don't quite see how I can get the center piece out. If you know, please send me a mail or even better drop a comment below this post so other people can benefit as well.

When taking the carbs apart, it can be vital to support  the float-pin-towers, in case said float pin is a bit stubborn. (Funny arrangement by the way, the floats are part of the float-chamber on those VMs!)

Ultra-sonic cleaning of the carbs in order to remove all the schmoo on the outside. 

Before and after. 

I let the (empty) bath set over night, but it's no use. This particular batch of the cleaning solution can't be under no circumstances re-used. 


If you've read any of my older posts, you know how the (dis-)assembly works. But honestly, I've never seen such a dirty carb. (Not surprised the pump was dead as well. Both came off the same bike!)

... and filled in some holes as I don't plan on running a rack on the back of the tub. Well at least not the stock one. I do have one in storage which is a lot bigger, but doesn't require any visible holes on the outside. Oh and yes, there were some other holes I had to fill in, but those were rather hard to take pictures of, so you simply have to take my word for it. 

 Next steps will be the installation of a new sidecar axle and building the sidecar brake, which I hope to have in place by some time next week. 

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