K Bike Tech

K75/K100: Improve Throttle Return

A common complaint about two valve Ks is that the throttle return is slow, sluggish or sticky. (Pick your favorite adjective.) This is often very easy to improve by simply using a thinner lubricant than the gooey grease used by BMW.

1 - Remove right combination switch: There's a small M4x12 Phillips screw that holds the combination switch to the throttle perch. If this screw has not been touched since it was installed at the factory then it may be difficult to loosen so use a good screwdriver with lots of pressure to initially break the threads free. If you don't then you risk stripping the head of that screw.

2 - Remove throttle cam cover: Remove the large Phillips screw to the right of the front brake master cylinder. Use a large tipped Phillips screwdriver or PH3 bit.

PH3 Bit

The cover may be a little sticky to lift off but it does lift straight up.

Caution: If you have heated grips then be very careful not to pull the throttle twistgrip out to the right or spin it around when the cam cover is removed. The heated grip wiring is attached to the outer end of the twistgrip. The wiring is delicate and very easy to break.

3 - Add new lubricant: You can be anal retentive and take the throttle perch apart to clean out all of the old grease first but it's easiest just to spray lots of new lubricant into the throttle cam area and save yourself a lot of extra work.

My preferred lubricant for this task is aerosol spray silicone. You should be able to find it at your local hardware or auto parts store.

If your bike does not have heated grips then remove the twistgrip and lubricate the handlebar surface as well.

4 - Reassembly: Your throttle gears may not look exactly like this picture from the BMW manual but there are indicator lines on both the throttle cam and twist grip that should be aligned when you push the twistgrip in and push down on the cam before reinstalling the throttle cam cover. There is no need to he-man the cam cover screw. Just get it nice and snug.

Before reinstalling the combination switch twist the throttle and let it go a few times. The return should be noticeably better than before. If there is little to no improvement then the grip rubber may be rubbing against the side of the throttle perch or, if you have bar ends, rubbing against the bar end weight.