Model Engine Company of America
It's easy to time the valve on a HP four stroke
The 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.
First you must remove the valve cover and the rotating valve. Pay close attention to the shims and/or bearing located in the valve cover.

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 place.
Insert the valve with the port window in the rotating valve between the intake and exhaust ports.
You should see a small opening of the valve in both the intake and exhaust ports.
Yes both intake and exhaust ports are open at the same time. This is usually referred to as valve overlap.
Replace all the shims and/or bearings. A new gasket is recommenced and can be purchased through our parts dept.
The 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.
 

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