Waterax MARK-3 Owner's Manual page 20

5. Start unit. Allow the engine to properly warm up (minimum of 2 minutes) before proceeding with the
adjustments.
Note: Do not run the engine with the choke engaged for long periods of time to warm up the
engine.
6. When engine is warmed up, return throttle to idle position. Adjust the idle speed regulating screw until
engine idles between 2,000-2,200 rpm for low speed jet adjustment. The pump pressure will be
around 30-35 psi.
7. To adjust the low speed mixture, quickly increase the throttle and observe the engine response
(return back to idle);
•
If the engine is running roughly and does not accelerate smoothly, slightly close the low speed jet
by turning the low speed mixture adjustment screw CW to lean out the mixture.
•
If the engine hesitates to accelerate, slightly open the low speed jet by turning the low speed
mixture adjustment screw CCW to enrich the mixture.
•
Repeat the procedure until the engine reacts smoothly when opening up the throttle.
The engine at idle should run a bit roughly (richer mixture), but not be on the verge of
Note:
"choking" due to an excessive amount of fuel. This will provide adequate lubrication at low
engine speeds where the engine fan cooling is reduced. If the engine runs "too" smoothly
(similar to a 4-cycle engine), this indicates that the mixture is too lean. Adjust
immediately.
8. Increase the speed gradually to full throttle setting. Adjust the high speed mixture:
•
Turn the high speed mixture adjustment screw CW and reach the maximum engine speed
(maximum pump pressure). Note: at this point, a slight turn CW would cause the engine speed to
drop resulting in a dangerously lean condition. Adjust immediately.
•
To obtain an optimal and safe mixture, open the high speed jet by turning the high speed mixture
adjustment screw ¼ turn CCW from the maximum engine speed setting obtained in last step.
There will be a slight decrease in engine speed (~100-150 rpm) and pump pressure (~5-10 psi).
9. Return back to idle and verify idle speed and low speed mixture adjustment. Correct if necessary. If
low speed mixture was adjusted, increase the speed back to full throttle and adjust the high speed
mixture.
Note: Do not adjust the low speed and high speed mixture too lean for the sake of
performance; improper adjustment will result in insufficient lubrication, higher
engine temperatures, and premature engine failure.
Note: It will be necessary to readjust the carburetor when operating the pump at different
altitudes.
A special offset screwdriver is available. It allows for an easy adjustment
of the low speed jet on the MARK-3 carburetor. Item number is 801147.
03/2016 – Page 20 of 52
WATERAX MARK-3 Owner's Manual