Sunday, 1 April 2018

The XS Triple Sidecar - modifying flatslides to fit

If you're running one of the more common bikes, you simply buy a set of flatslide carbs second hand, slap 'em on and there's probably even some info out there on how to jet them so you at least have a point to start. But I wanted a triple.

First step was to get the spacing right. As you can see these carbs are spaced pretty tight already. (At least #1 and #2 are.) In order to do that the old carbs had to come off and I had to take some measurements. 

It became apparent that the only way to make this work would be by moving the fuel inlets on the two outer carbs to the outside, as each pair of carbs had to be spaced more than 25mm closer together and at the very most seven or eight mm would have been possible. Luckily the castings were all identical, just drilled according to the individual requirement. As such it was just a matter of drilling out the fuel passage from the other side and then thread both sides.

In order to gain another nine milimetres, the casting boss was milled flush with the carb body.

As there wasn't enough meat to tap the carb bodies in M8x1.00, I had to make three adaptors to use some industrial/hydraulic Lego.

Testfitted the carbs onto the engine. As I have used this type of carbs before on the XS400 RatRacer, I still had a piece of throttle shaft left over, which I used to straighten out the carbs and have them sit as perfectly straight as I could to prevent binding later on.

Quickly tacked the rails together for a test-fit.

And then re-tap (M4) the throttle shaft to accomodate for the new spacing. 

And then shorten the throttle shaft on the lathe. (Did I mention, that I got myself a MGEHR16 parting tool? It's the dog's d*ngl**s...)

Sorting out the choke linkage was a beautifully simple job, as it only meant to cut a bit of 4mm stainless rod to length and tighten up the hooks of the choke setup. 

Installed and looking d*mn sexy. 

They say that every great triumph needs a bit of tragedy. 

This one needed a bit of re-engineering. The solution will be found in the next post.

(Oh and yes, the VM36s will be for sale, once they received a half-decent cleanup.)

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