Control cables on your motorcycle: care and repair
If your throttle, choke, clutch, or drum brake starts become sticky, you need to take an urgent look at the levers and control cables.
Instructions on how to maintain and repair the control cables on your motorcycle
The first thing to ensure is that the control cable is routed without any kinks and in as wide an arc as possible. If it's pinched or has any tight bends, the force required to operate the lever is greatly increased. If the throttle twistgrip no longer closes automatically, this may be due to less than ideal cable routing, the throttle tube rubbing against the handlebar/hand control/bar end, a faulty cable core, or insufficient lubrication.
Correct lubrication of the control cables
Regular thorough lubrication is essential to prevent premature cable wear. Always use a special control cable spray if the cable has a Teflon inlay, which is recognisable as a thin whitish tube inside the cable sleeve, as oil would cause the Teflon to swell. Oil (ideally not too low-viscosity) must only be used to lubricate conventional control cables without a Teflon core – but the special control cable spray can be used for these as well. A cable oiler ensures perfect application to the interior of the cable. The cable is sufficiently lubricated when the lubricant emerges from the bottom end. If using oil, you can hang the cable up overnight to allow the oil to run through effectively and to catch/remove any excess.
Always inspect your control cables regularly, and if you discover any broken individual wires, replace the cable core or the entire cable as soon as possible before it breaks when you're on the road. Prudent bikers always keep a "repair kit" with them containing spare control cables and screw nipples. Check that you have the right nipples for the controls on your bike model and, if not, add them to your repair kit. Always carry a suitable screwdriver and a pair of pliers for gripping so that you can tighten the nipples securely without damaging them. You will also need wire cutters to cut the wire to length. Special control cable cutters work best, as they don't squash the wire, but a good pair of long-handled wire cutters will provide enough force – whereas standard short nippers or side cutters are not very effective. Screw nipples should only be used on the clutch cable as an emergency repair to get you to the nearest workshop. Never fit brake cables with a screw nipple. If your brake cable fails, it's best to have the bike towed to a workshop. Choke and throttle cables transmit low forces and may be operated permanently with screw nipples if they are well secured. But even with these cables, soldered nipples are the more professional option.
Making your own control cables
If you do not have a prefabricated cable to hand, or you need a different length - if you have fitted new handlebars, for example - you may need to assemble your own control cable. This is a relatively easy and inexpensive job. You can buy control cable inner core and outer casing by the metre, while nipples and adjusters are available separately. What to do:
- the core must always have a certain amount of play inside the cable casing to allow it to move in small radii with low friction. For thin throttle and choke cables, a play of 1 mm is sufficient; thicker clutch cables require 1–1.5 mm of play.
- First check carefully on your original cable which nipple sizes you need. Sometimes Japanese motorcycle manufacturers use nipples that aren't commercially available. Clever DIY mechanics do not let that bother them, however, they just make nipples from thin brass rods – which you can get from your local DIY store.
- Remember to order end ferrules as well. You can often use the adjusters from the old original cable.
To make the new control cable, you will also need a soldering iron with at least 80 W capacity or, better still, a blowtorch, some solder, brake cleaner and definitely liquid flux (also available at DIY stores) to clean the core beforehand.
Generously measure the cable outer and inner, based on your original cable or the installation position on your motorbike (making adjustments for length if you are using new handlebars). Solder a nipple to one end of the cable core, assemble the cable and trial-fit it on the bike to measure the exact length to the controls. Make sure that any adjusters have been screwed back to their basic setting and that the clutch release on the engine is also in its basic setting, but don't forget to factor in the requisite amount of play in the cable (approx. 2–3 mm) and to leave the core protruding a few millimetres out of the loose nipple so that you can solder it. The cable outer must lie correctly in the adjusters - not on the outer edge - so that you can optimally cut the core to length (see Fig.5)! Take care to check everything thoroughly before proceeding, because you can no longer adjust the cable once you have soldered the second nipple. Then take off the cable, and solder on the second nipple.
Instructions: Correct soldering of control cable nipples
Clean the end of the cable with brake cleaner. Push on the nipple, leaving the end of the core protruding a little. Clamp the nipple in a vice and spread the individual wires of the core with the screwdriver so that the nipple is not as easy to pull off. This makes for a more robust soldering point later.
Cleaning the soldering point
Dip the end of the cable with the nipple into the liquid flux to clean it thoroughly, as otherwise the solder will pearl off the wire. Cleaning with brake cleaner or thinner is not enough!
Soldering the nipple
Heat the nipple with the soldering iron/blowtorch. Do not heat the core to glowing, as this could make it brittle. Now apply solder from above to the spread-out end of the core. The soldering is perfect when the solder flows right into the nipple and a very small amount emerges at the bottom edge. This is the signal to immediately stop applying solder, as a build-up of solder at the bottom of the nipple would make the cable stiff and liable to break at this point.
Filing the soldering point smooth and cutting the control cable to length
Allow the nipple to cool. Now file the head of the nipple smooth. Prior to installation, lubricate the finished cable as described above. When installing the cable, check that it does not rub unnecessarily on the control, because this could cause premature wear. Smooth off any rubbing points with a file/sandpaper.
Make sure to allow sufficient play. If a throttle cable is too taut, it could distort the engine idle speed or open the throttle unintentionally when the handlebar is at full lock. Too little play in the clutch can cause clutch slip. There should be 2–3 mm of play in the clutch cable.
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The Louis Technical Centre
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These tips for DIY mechanics contain general recommendations that may not apply to all vehicles or all individual components. As local conditions may vary considerably, we are unable to guarantee the correctness of information in these tips for DIY mechanics.
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