HP four stroke engines utilize a rotating drum valve in the
head rather than conventional poppet valves. As the drum rotates
the port lines up with the various stages of a four stroke cycle.
Intake, compression, ignition, and exhaust.
you must remove the valve cover and the rotating valve. Pay
close attention to the shims and/or bearing located in the valve
Find TDC, top dead
center (when the piston id at the very top of the stroke)
You can place a pen down into the cylinder and turn the crankshaft
until the piston comes u
It is easier to
mark the prop driver and crankcase at TDC. You may notice
a mark on the prop driver from factory assembly. This may
or may not be at TDC on you engine because if the prop driver
was ever removed it probably wasn't put back on in the same
the valve with the port window in the rotating valve between
the intake and exhaust ports.
should see a small opening of the valve in both the intake and
both intake and exhaust ports are open at the same time. This
is usually referred to as valve overlap.
all the shims and/or bearings. A new gasket is recommenced and
can be purchased through our parts dept.
above information is provided as a guide. Since MECOA/K&B has
no way of determining the ability of the individual using and understanding
this information, we assume absolutely NO RESPONSIBILITY for any
damage to person or property from the use of this information.