Engine Balancing

Longstroke vs shortstroke in two stroke engines
PMB Model Boats
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Longstroke VS shortstroke. Differently to four strokes, a short stroke is not higher power/higher revving in a two stroke engine. The port area available in a two stroke engine is proportional to the the cylinder wall area not the head area. This favours long stroke/small bore The limitation is friction/wear and inertial effects and so the best stroke/bore ratio seems to be between 1:1 and 1.2:1.

Rod/stroke ratios. A rod stroke ratio of 1.75:1 will give a good wide powerband. A rod stroke ratio of 2:1 will give a higher revving narrower powerband.

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