Having recently finished the engine I found myself with a desire to design my own engine based loosely on Eds "Holly Buddy" and David Owens "Owen Mate". That is a Front Rotary Valve (FRV) engine that would be relatively easy to design and build for a beginner like myself.
Immediately I came across a rather big stumbling block. That being, I haven't got a clue what I'm doing. ��
So I decided I would reverse engineer Ed's engine. Starting at the beginning I thought it might be prudent to understand the port period angles, that Ed mentions in the introduction, that come with the drawings ie 107° transfer period, 122° exhaust period and 140° intake period.
I spent two evenings trying to come up with figures that matched Ed's. I failed miserably. I then got in touch with Ed who confirmed that his figures could also be wrong.
I then searched Google for "2 stroke port timing calculator" and found myself on Ron Chernich's fantastic site. http://modelenginenews.org/index.html
To find the calculator, in the yellow bar on the left, click resources, design centre, Front Rotary Valve (FRV)
I entered all the required dimensions and the calculator spat out the timing diagram.
I then sent a message to Ed with the timing diagram. He has asked me to include it here for completeness .
As I stated earlier I'm very much a beginner. If anybody spots an error can they please correct it here.
Steve ( on behalf of Ed)