ENGINE ADJUSTMENT
Every engine has been adjusted to average mixture settings which will most likely allow the engine to
start and run in most locations. However, as altitudes and barometric pressures vary by location, it is very
likely that the carburetor mixture settings will need to be adjusted to obtain optimum performance.
(1) Choke Lever
(2) Throttle Lever
(3) Idle Speed Adjustment Screw
(4) Low Speed Mixture Adjustment Screw
(5) High Speed Mixture Adjustment Screw
ADJUSTMENT:
A general starting point is
1.25 turns out for the low speed needle (4)
, and
1.5 turns out
for the high speed needle
(5)
.
Low Speed Adjustment
Adjust the Low needle until you achieve a smooth idle and a reliable transition to
high throttle. If the engine dies when the throttle is advanced, the mixture is likely too lean. If the engine
stumbles when the throttle is advanced, the mixture is likely too rich.
High Speed Adjustment
The High Speed needle adjusts the mid and high RPM mixture setting. Best prac-
tice is to set the high speed needle to achieve maximum RPM and then open an 1/8 of a turn to allow for
altitude. If ever the engine slows or stops while at full throttle, the high speed mixture is most likely too
lean. In this situation open the High Speed Screw 1/8 to 1/4 of a turn.
Caution: Don't be tempted to run an overly rich mixture. A too rich mixture will only result in poor en-
gine performance (engine stopping or spluttering when accelerating or deaccelerating), pre
-
mature car-
bon buildup, a fouled plug and excessive exhaust residue. However, a lean mixture will also damage
the cylinder and piston. A lean run engine is not covered under warranty.
During break in and after few runs at full throttle we suggest you unscrew and check the spark plug, it
appears to be a slight yellow colour if mixture had been set properly.
