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December 29, 2003
You are correct, in a perfect world, the pressure would balance out to be zero, but a little pressure sneaks past the rings, the valve guides, etc and any positive pressure pushes oil out the rear seal.
Interesting side tangent when talking about two cycle engines. When I was a 16 year old kid, I worked for a marine place and we built racing Johnson outboard motors. Roy Rogers,( the great cowboy movie star) had us build his engines. Twin Johnson 35's for off shore racing. My boss and I drilled the crankcase full of holes and inserted one and two inch long brass bolts and nuts with lock washers into the crankcase space. Then I bent them all over and around each other. Then I put about 20 layers of masking tape on the crankshaft to make the counterbalances larger by about 1/16 to 1/8 inch. Then I filled the crankcase with Bondo, all around the brass bolts and put in the crank and spun it around in the Bondo. That made a hole in the Bondo about 1/8 inch larger than the crank, effectively reducing the crankcase volume to close to zero! When the Bondo cured, I took a die grinder and rounded the edges and smoothed out everything for good air flow and the crank just cleared everything, creating a rapid response and "stuffing" of the air/fuel mix to the reed valves and tons of horse power.
Sorry for the non LBC, just a little side story about two stroke crankcase pressures......
Cheers,
Bob in San Diego
A backward poet writes inverse.
"Robert D. Gardner" < rdgard@... > 27908
Posted on December 29, 2003 06:12 PM
Posted to category(s) Cylinder Head | Engine (external) | Engine (internal) | Exterior | Fuel System | Gauges | Intake System | Lubrication System | Miscellaneous | Racing | Tuning
