yak-54

Hi to everybody
i have a question to ask regarding a comression
when i turn slowly the propeller to the left its feal like low comression when the engine dry
but if i turn the prop to theright there is a ton of comression can someone explain why is that
thanks?
ilan</p>

pe reivers

the piston seals the piston ring slot better in one direction.

Tony Hallo

Do you have a rotary valve engine such as ZDZ?

Truckracer

My Feedback: (19)

When turning the engine backwards, the angle of the connecting rod puts side forces on the piston in the same direction as when the engine is running. This more closely matches the ring and piston to normal wear, thrust and alignment patterns in the cylinder than when the engine is turned in the normal direction. Most all engines will have more cranking compression when turned backwards. This is normal.

Ernie Misner

The orientation of the ring gap plays a factor in the side forces when being turned one way or the other also. Normal but strange (at first stuff)

Another interesting anomaly is that a 4 stroke will seem to be weak on compression when being turned over when the carb barrel is fully closed.

Ernie Misner

captinjohn

That is because when carb is fully closed....its hard to get a full shot of air on the intake cycle to make compression. After all...it is the amount of air that is squeezed into a smaller place. Not much air in=not much compression! Capt,n