Starter (Choke) - Yamaha XS850G Owner's Manual

ON:
With the lever in this position fuel
flows if the engine is running but stops
if the engine is not running.
RES:
This indicates "RESERVE". If you run
out of fuel while riding, move the lever
to "PRI" and switch to "RES" posi-
tion after starting the engine. Then, fill
the tank at the first opportunity.
NOTE:
In the "ON" and "RES" positions the petcock
works on pressure from the engine turning
over. If the line connecting the petcock to the
carburetor intake manifold is not connected
or has a leak the petcock will not function
properly.
PRI: This indicates "PRIME". With the fuel
petcock in this position fuel flows
whether the engine is running or not. If
the fuel tank is completely empty, refill
the tank, prime the carburetor in this
position, and then switch to the "ON"
position after starting the engine.

Starter (CHOKE)

When cold, the engine requires a richer fuel
mixture for starting. A separate starter circuit,
which is controlled by the starter, supplies
this mixture.
The starter on this model is a 2-position type
as follows:
1. Pull the starter fully up.
-When starting a cold engine.
2. Push back the starter half-way.
-When warming up the engine.
NOTE:
Refer to "Starting and warming up a cold
engine" for proper operation.