Hi Fellows,

What is the general opinion about the need to change thepiston ring; should that be
like gradually up to 15% drop in rpm at the same propeller-gl.plug-fuel for example,
or what is a better indicator to follow ?
Specifically I am interested in Two Stroke engines, like OS.91FX and OS-BGX but
of course all good advices are very important to me too.

Regards,
Nick</p>

Impossible to run in idling, difficult to start the engine cause loss of compression, can not keep compression long enough when the engine are rotated slow, possible you can listen the engine will give a "hiss" sound from crankcase wihout back cover.

There is no set rule. I would chance it when you cannot handstart the engine and idle begins to degrade. A loss of 15% RPM on top would be huge and equate to almost 1/2 powerloss. The top rpm will not suffer asmuch from low comp as the way the engine handles at lower rpm.

When you do replace a piston ring....get a Frank Bowman ring. You then will have the best compression. Capt,n</p>

<u>A lot of thank to all who answered !!!</u></p>

Nick</p>