RPM/Governor Adjustment Tips
RPM/Governor Adjust Tips:
The most common PM questions I get concern RPM, props
and throttle adjustment.
The question really is, can I make my mud motor go
Chances are, you probably can. I haven't seen one yet
that we can't make go faster for under $200 and many
times do it for nothing. Self help is best.
Longtails with lever style throttle.
Set the friction adjustment screw to hold your throttle
wide open. Have someone hold it open, if necessary.
Loosen the throttle cable clamp located by the muffler.
Pull gently until the throttle lever hits its stop. In
many models this is a high speed governor adjustment
screw or fixed bracket. Tighten the cable clamp snug. Do
not over tighten.
Start the engine, let idle for one minute and then run
wide open. Check tach for 3850 to 4000 rpm depending on
the mm manufacture engine spec requirements. Most can be
run at 3900.
If the engine does not run at least that high, you will
need to adjust the governor. Now this gets tricky and
why many manufacturers prefer not to give any more
As long as you do not run more than 4000 rpm out of the
water, the only way you can screw up a governor is by
not tightening the adjustment screw causing it to loosen
and over-rev later.
Here goes. The governor is connected directly to the
butterfly lever on the carburator. The throttle you use
is connected to the governor by a governor spring. The
governor isn't magic and doesn't control your life,
however, without adequate pull by the throttle through
the spring, its objective, to slow down the engine can
limit your max RPMs.
So, we want to exert more pull than the governor, thus
controlling top speed RPM out of the water. I will talk
about how that relates to the in-water, under-load speed
The governor either has an adjustment screw or a tab.
The adjustment screw obviously moves the stop allowing
the throttle to pull further on the spring, or a tab
that does likewise. Many Vans have a tab, Kohler and
Kawi, a screw. So, adjust the screw or tab to pull
further or harder on the governor spring. Each time,
incrementally. Check the RPM, each time doing so more
carefully to ensure you don't over adjust and cause
over-revving problems. If this doesn't work, there is
The Governor Spring: The governor spring on your mud
motor is designed to exert a set amount of pull on the
governor. Most springs are color coded reflecting what
RPM they allow the engine to achieve. You can get a new
spring if one is old and stretched, or replace it with a
color code that is stiffer with more RPM.
Governor Spring Arm: The governor spring on most motors
is connected to the governor arm or throttle arm. There
is normally more than one hole to connect the governor
spring. When we can't get an engine to the desired RPM,
we move the spring out further on the arm to another
hole, thus providing more leverage.
With this knowledge you can adjust your governor for the
performance your manufacture intended.
Governor and in-water performance. The governor when
properly adjusted has nothing to do with how fast the
motor runs in the water. However, there are exceptions
and a simple test, provided the engine under load is
running less than 3900. (But, first be safe, be in open
water, have full control of your motor and be familiar
where the carburator throttle linkage is located.) (This
test is not subject to motor type, boat type, load,
elevation, or any other conditions.) With the throttle
wide open, and RPMs running lower than 3900 RPM, reach
around and press the carburator butterfly arm or
governor linkage and see if there is any additional
throttle left. Visually, you might be able to see the
throttle arm pegged out on its stop or not. If there is
throttle left, replace the governor spring and/or give
us a call for help.
When all this is done, then we fine tune the propellers
for a given load. We can talk about this later.
Hyper - The twist or squeeze throttle both adjust the
same as above, except most of the Hyper motors run at
4000 RPM by design.
Tip: While you are adjusting the throttle cable in step
one, add a fingertip of grease to the cable near the
cable sleeve, and tie the cable up on any part of the
motor so it is higher than cable end. This will keep
water out of your throttle cable and prevent freezing