How to make cables
Oli gets that new bike feeling thanks to new cables
IRECENTLY MANAGED TO FIND A PAIR OF NEW-OLDstock Mikuni VM34 slide carbs for my Yamaha XS650at an auction. The original and worn out B538carbs are CVversions and operate using a single throttle cable which opens the butterflies in the carb bodies. The VM34s are traditional slide carbs, which need a throttle cable each.
The new carb set came with these twin cables, joined to single throttle cable at a converter that sits just shy of the steering head, under the tank. The XS650 SpeciaVUS Custom these cables were designed for comes with high bars, but while my bike is also a Special, I long ago ditched the high bars for a set of flat drag bars, as I quite like motorcycles that handle properly. As a result, the single cable was about
18 inches too long, and needed to be shortened.
I'm not keen on hacking about at already perfectly serviceable kit, and in any case a decent spare throttle cable is handy to have, so rather than just spending time tracking down nipples and chopping up the existing cable, I decided to make my own and purchased a Venhill universal throttle cable kit.
The Venhill kit consists of a long cable outer, an even longer length of galvanised wire inner cable, some
rubber covers and a selection of adjusters, ferrules/cable ends and nipples.
Before getting to work making the cable, I needed to make sure the shortened item would fit and would be of the correct length.
The Venhill cable comes with a nipple already attached at the carb end. I therefore needed to cut the cable to length at the throttle end before attaching the cable adjuster and throttle nipple. This involved a good deal of checking and fitting before it was done.
The first issue was the use of the converter. Even though there were four different spare cable ends and one 6mm item fitted already to the cable outer, none of them matched the converter, which had a 6mm hole, so I had to gently ream out the hole in the converter with a 7mm drill to accept the fitted cable end.
This done I now needed to select the correct fittings for the throttle end. The various connectors in the kit would have been fine for most British bikes and would have worked on the Yamaha, but to fit an adjuster I would have needed to split the already short outer near the twist grip and put one section on either side. On the original Yamaha cable a guide tube and adjuster sticks out of the bottom of the twistgrip, and for the sake of neatness I wanted to retain it, so I cannibalised one from a now redundant new cable salvaged from the old carbs.
Then I had to match the correct ferrule for the cable outer with the correct adjuster from the four ferrules in the pack and the two adjusters.
Next, I needed to measure the outer so I could cut it to length, taping it in position and ensuring it would attach to the throttle without it snagging or stretching at full lock.
The new cable was going to be quite short. After fitting it, measuring it, fitting the tank and checking the length and the amount of play again, I taped the adjuster to the outer at the appropriate place, and clamped the cable outer in a vice.
Rather than using plier type cutters or a hacksaw to cut the outer, which can untidy things to a cable if you are not skilled, I used one of those cheap Dremel copies you find in German-owned supermarkets. It did cut the cable neatly, and I could grind the few burrs off, getting through several tiny cutting discs in the process. Next the outer cable ferrule was popped on and secured with a light blow from a punch. The adjuster was fitted, and all seemed to go together nicely. I also had a lot of cable outer left over which went into the 'might come in handy later' pile.
The next step was to measure the cable inner, and to solder the nipple to the throttle end.
Again, measuring was required, so I used the original cable as a template. While it was far too long in itself, the actual length of exposed end was going to be the
so it was cleaned off with some acetone, some wet and dry paper and wiped clean of bits of metal and grease.
After sliding the nipple on with the wide hole towards the open end, the cable needed to be 'birdcaged'. This is a process which involves opening up the strands of wire at the end and bunching them back together again to make a tiny cage. Venhill makes a tool set for this, involving some punches and clamp to be put in a vice. It's very neat and would be very useful if you were making lots of cables. But at upwards of £100 it's a bit of an expense. I made something similar out of two right angled pieces of alloy and drilled a 1.5mm hole in it, with a 4mm countersink.
Then I used a small punch, tapping it with a soft hammer, to create a rather less neat birdcage than the Venhill tool would have provided, but it still worked.
I slid the nipple up to the birdcage, pulling the cable down so the birdcage was snug inside the nipple, with a few strands sticking out and enough space for the solder to penetrate.
I made a solder pot utilising a brass plumbing pipe end and melted electrical solder into it with blowtorch to fix the nipple to the end by dipping the nipple into the melted solder.
Using the solder pot helps make sure the solder penetrates the wire strands, and completely covers the nipple. Using a soldering iron to heat the cable is tricky.With different sorts of metal involved, if you are not careful you get blobs of solder everywhere, except where you want it. I had to try not to get any solder on the cable on the other side of the nipple, as this makes it inflexible and puts it under strain when in use.
It was dipped in water to cool it and wash any flux off.The end was dried, cleaned and a small file used to get rid of any excess solder and exposed cable strands so it would fit smoothly into the twistgrip. A little light oil - Three in One will do it - gave things a bit more protection, and the cable was complete.
The basic principles used here are the same for heavier duty control cables for clutches, but you really need to be confident of your ability if you are going to tackle a brake cable. A failed throttle or clutch cable might leave you stranded. A failed brake cable doesn't bear thinking about.
Goodquality pre-made cables formost popular models are available relatively cheaply, so making your own is a task you'll only need to perform in an emergency, if you simply can't get the right cable, if you like doing this sort of thing or if, like me, you're fitting something non-standard.
Making a cable does require you to know how to solder and to have some mechanical competence with hand tools. It is a really good idea to practise soldering with spare lengths of cable before doing the final assembly, and I made half a dozen practice birdcages before I got that part of the process right. Cable making is satisfying to do and a useful skill to have. rnml