Throttle Cable And Choke Cable Replecement - Bryan Lally - BMW R850 Maintenance Manual

Throttle Cable and "Choke" Cable Replacement, and Service of
the Cable Junction Block on a Late Model Oilheads - Bryan Lally
Bikes effected:
These instructions are for an R1100RS with the cable junction block (crank
wheel) throttle cable. It should be a very similar operation on any of the oilheads
except for the differences in fairings and trim parts. These instructions do not
apply to bikes with the crossover cable throttle arrangement.
Why did I do this?
The fast idle cable on my oilhead (at 3400 miles) started to "stick." When the fast
idle lever was moved from the normal position to the detent or start position, the
cable worked normally. But when the lever was returned to the normal running
position, the cable would go very slack and the throttle butterflies would not
return to the idle stops. Putting tension on the throttle cable would cause the fast
idle cable to snap back to its normal state (and the butterflies would close).
After some thought and considerable pulling and wiggling of cables, I decided I
needed to take a good look at the junction block assembly.
Short Story
The fast idle cable pulls on a small ramp, which pushes on a flat on the crank
wheel, turning the wheel and opening the throttle butterflies by way of two short
cables. The ramp acts like a wedge between the flat on the wheel and the slot
that the ramp slides in. There is a return spring for the fast idle ramp and cable
located at the junction block assembly. The ramp would not release from its
wedged position; it was being held in place by the tension supplied by the throttle
butterfly return springs through the short cables. As soon as the throttle handgrip
was turned, the ramp was released from contact with the crank wheel and
returned to its rest position by the fast idle cable return spring. The junction block
assembly was put together completely dry, with plastic sliding on plastic. A small
amount of grease was used to lubricate the ramp and the slot that it rides in; this
eliminated the clamping effect on the ramp and fixed the problem. In my opinion,
this should not have been assembled dry.
Replacing Throttle Cables on Junction Block (new style) Oilheads
Remove the seats.
Remove left and right fairing pieces.
Remove the air snorkel that feeds air to the air cleaner.
Remove the fuel injector covers.
Unplug the wires that trigger the fuel injectors at the injectors, or else they will be
in the way.
69