BMW R850 Maintenance Manual page 67

now locked and set. This is the last TPS adjustment you will need; it is now set. You
will not change the position of the TPS again !! [Author's note: The throttle opening is at
zero and the TPS value is at zero, which explains Rob Lentini's title of "Zero-Zero" for
this procedure.]
Step 6. Move left throttle plate stop screw to obtain .370 volts and lock screw.
With the ignition still on, turn the left throttle plate stop screw clockwise (CW). By turning
the screw, the flange will be moved away from the throttle plate. Continue turning the
throttle plate stop screw until the voltage starts to rise, and continue until you reach 370
millivolts (.370 volts). Stop there, and lock it down with the lock nut. Blip the throttle
several times to check the accuracy and repeatability of the 370 millivolts. Readjust the
throttle plate screw if necessary. Remove the DVM, remove the object inserted into wire
#1, replace the rubber boot onto the TPS.
There is a possibility that .370 millivolts will not be the correct adjustment value for your
bike. This will be explained in Step 10.
Step 7. Large brass bypass screws in, bike on, warm engine, rough idle expected
On the right side of the bike, on the outer surface of the throttle body tube, is a large
brass bypass screw with a slotted (NOT Phillips) head that faces toward the rear of the
bike. If you were to place a screwdriver on the screw, the handle of the screwdriver
would point toward the right rear turn signal. This large brass bypass screw is
approximately one inch forward of the black plastic air intake tube. You are looking for it
on the right side because it is easier to locate there; there are fewer things in the way.
You can see the large brass bypass screws easily when standing near the turn signals.
If you look on the left side, you will find a similar large brass bypass screw. The official
BMW Repair Manual calls this a "recirculating air screw" at page 00.27.
Count and record the turns you make to lightly seat both the right and left large brass
bypass screws by turning them clockwise with a flat screwdriver.
Position a fan near the front tire with its output directed at the cylinders equally to avoid
overheating, or use two fans, one directed to each cylinder. If your bike has a Rider
Information Display (RID), allow the oil to heat up to 5 bars, otherwise idle the bike for
five minutes. It will idle rough because it is not in synch. Do not be concerned about a
rough idle at this time.
Step 8. Turn the large brass bypass screws out in 1/4 increments if bike will not idle;
attach carb stix
If the bike will not idle at all, back both large brass bypass screws out in increments of
1/4 turn until the bike will sustain a rough idle.
Secure the mercury manometers (carb stix) on the right side on the bike, where most of
the work will take place. Use any method that secures the carb stix (and the hazardous
mercury) vertically while the bike is running , such as hanging the carb stix from the
ceiling.
There is one black tube attached to the under side of each throttle body. Remove both
black (vapor recovery) tubes and you will expose the brass nipples that point down.
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