GS throttle cable swap

So today I swap my throttle cables. I pick up the new cables at lunchtime from Portland BMW…

…there are 4 cables and a splitter box. A main throttle cable leads from the twist grip to the splitter box, then 2 shorter cables lead to the respective throttle bodies. A separate “cold start” cable runs from the left hand grip to the splitter box.

Ricardo has told me that he’d rather do a rear drive swap than a throttle cable change, a thought which fills me with confidence as I approach the bike…

First off – remove the tank. A simple enough task – I find a prop of some sort…

…in this case a mallet, is a useful way to gain access to the fuel line quick-disconnects.

Soon the tank’s off…

Some of you who have GSes may find my bike a little different to yours. This is for various reasons: I don’t have ABS, so there’s a big gap ahead of the battery, where the ABS pump would live; I have an alarm and a Techlusion 259, as well as various other electrical bits fitted, so try to ignore the odd coil of wire cable tied around the place…

Back to business. You only need to remove this one bolt to gain access to the twist grip end of the throttle cable…

Take off the plate and disconnect the cable (excuse the focus – point and shoot one handed )…

At this point, I threaded the new cable alongside the old one, to make sure it followed exactly the same path, to avoid it getting kinked or trapped.

I undid both the left and right (pictured) cables at the throttle bodies.

Undo the 10mm locknut, unscrew the adjuster and, after feeding the cable through the gap in the plate, disconnect the spring clip on the inner side of the throttle body to release the cable. You have to do this by feel, but you’ll get the idea when you try it…

The splitter box lies directly under the ABS Pump plate, in a specially designed niche. It’s difficult to photograph, as it’s partially obscured by the crank case breather hose…

To disconnect the “cold start” cable, I first removed the bar end weight and moved the handguard, for ease of access. As with the throttle side, you only need to remove one bolt…

…apologies again for the standard of pic…

…to remove the lever – once again, the cable can then be easily disconnected. I ran the new cable alongside the old one.

Time to remove the splitter box…

First, lift the breather hose out of the way (or as far out of the way as possible)…

…then depress the spring clip at the bottom of the housing…

…before steadily pulling the splitter box out…

It may require some persuasion – mine had been there since manufacture in early 2002, and had done 74k miles…

…but eventually it came out. It was full of dust and crap, but, for all that, the cables still operated smoothly…

The wheel which the three throttle cables attach to is held in place on its shaft by this circlip…

…probably not a good idea to lose it.

Cold start cable operates a cam which cracks the throttles open by a fraction to boost idle speed on cold start up…

…getting this long spring to stay put whilst re-assembling the cables onto the wheel is fun – if you have 3 hands…

Time to re-insert the splitter box…

Re-assembly is simply a reversal of the strip down. When fully re-assembled I did a full throttle body synch (see ADVRider Hall of Wisdom, if you are not familiar) and a TPS re-set (remove Fuse No 5, turn ignition on, roll throttle fully open, pause, fully closed, pause, repeat – ignition off, replace Fuse No 5).

The result? Well, despite the throttle action previously being smooth and there being no visible kinks or frays in the old cables – the difference is remarkable. The bike feels very smooth (nearly all of the previous “surging” has gone) and extremely responsive and the throttle considerably lighter. I kept thinking I was in a lower gear than I actually was. I’d advise anyone with a high mileage oilhead with original cables to consider doing this – 4� hrs well spent

EDIT MikeP from UKGSer has recently done this job and has fitted the modified throttle cable guide kit which you now need to fit new cables to pre Dec 2004 bikes – his write up follows:

Mike O has detailed the cable-swap and his guide can be found on the AdvRider Hall of Wisdom:

http://advwisdom.hogranch.com/Wisdom…le%20swap.html

If you are contemplating doing the same and your bike was built before December 2004, then you will get a different main cable (the one from the throttle-grip to the splitter-box) and you will need the replacement guide.

The new cable cannot be fitted to the old guide.

The new cable is Part # 32737692561

The new guide is Part # 32727691990 (listed as SET: REP.KIT ACCELERATOR CABLE DEFLECTION) on the BMW fiche.

Here’s what it is:

It took a little head scratching to see where the new parts went and what exactly they replaced and how, so this may save you some similar puzzlement.

Remove the hand-guard, the end-weight and the mirror.

Locate the bottom cover screw of the switch-block:

There is another screw holding the bottom cover in place at the extreme end of the underside near the brake master cylinder. Mine was solid and rather than chew the screw-head, I just pulled the plastic bottom cover down a bit.

Locate the self-tapping screw that is hidden by the (now removed) mirror stalk and remove it:

Lift the switch-block clear (it needs to be off of the throttle guide under the rubber grip) so that the twist-grip can be slid along the handlebar.

If your bike has heated grips, feed some more of the control cable into the handlebars to allow you to pull the twist-grip along the bar a little.

You need enough room to be able to get at the two (now exposed) cross-head screws (replacements are included in the kit). They are removed in this photo:

Once you have the screws out, you can slide the old cable-guide towards the twist-grip. It is located on the lug on the underside of the handlebar and has a ring of plastic around the bar:

Rather than removing the twist-grip from the handlebar completely, just snip the plastic ring in a couple of places (you won’t be needing it again):

It’s pretty obvious where the new parts fit so I won’t insult your intelligence, you will end-up with an arrangement like this:

and a pile of redundant parts like this:

The modification is apparently because the old parts allowed the cable to jump out of the guide (that’s what I was told anyway) but the up-side is that the cable adjuster at the twist-grip end is easier to work than the old one.