BMW R850 Maintenance Manual page 55

throttle body cable, because this is where you will make the part-throttle
adjustment. There is no need to fiddle with the cable adjuster on the left-hand
throttle body.
Start the bike. The mercury should come up a few inches in each tube, and if
they are at different levels, this indicates a different amount of air is being drawn
by each cylinder. Using the bypass screws on the top rear of each throttle body,
align the two levels. Small rotation (i.e. less than half a turn) of the screws
should be all that is required to achieve this.
Once the idle balance is set, you should do a part-throttle setting to ensure that
the butterflies are opening identically. Use about 2500 rpm. Hold the throttle
open at the set speed, and adjust the knurled portion of the right side throttle
body cable adjuster with your other hand to align the mercury levels. When the
levels are even, let the bike return to idle (checking alignment again!), and if all is
well, tighten the locknut on the cable adjuster, making sure that the adjuster does
not rotate with the locknut and mess up your adjustment. Sometimes it is easier
to hold the knurled adjuster with a set of needle-nose pliers while you tighten the
locknut with your 10mm wrench. Recheck after tightening, as the adjustment may
change when turning the locknut.
Congratulations, you have done your first throttle synch. Now go out and ride
until you can't see out of your mirrors again.....
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