Cruise engine RPM

[arizonarotors]

I have to admit my ignorance.....again!
Although I have significant experience operating Lycoming and Continental engines I have exactly 32 hours of Rotax 9 series experience.
I find that my 2009 Gobosh 700 flies at about 100 knots, using 4.8 GPH, at about 4900 engine RPM.
It is a comfortable ride and is flying plenty fast enough to bore holes in the sky.

The prop seems to be pitched okay. At a 1000 foot DA the full throttle engine RPM in the climb, at 70 knots, is about 5300.

Now the question. Am I hurting the engine by cruising at this RPM? I follow discussions that indicate people avoid cruise operation below 5000, or even 5200, RPM.

Thanks,
Jim

[3Dreaming]

A good check for prop pitch is to check full throttle level flight RPM. The number should be in the neighborhood of 5550 to 5650. I would guess that with 5300 in the climb it is pitched a little flat. Another thing is that the carbs tend to run lean in the mid range. With a flat pitch and the lean carbs I would expect a high EGT. If your EGT and other temps are staying cool enough, then there is not much issue with running those RPM's, but if it is getting hot bump the throttle up a little. Also if you are pitched to flat get your prop pitched.

[arizonarotors]

Thanks. I'll check WOT engine RPM on the next flight.
There appears to be quite a bit to learn about this little engine.
Jim

[arizonarotors]

Went flying this morning.

WOT 5650 engine RPM.

Level flight, OAT 55F, Altitude 2000 MSL. IAS 130 Kts.

EGTs: 1185/1200. CHTs: 152/154. Oil temp: 158.

Oil: Sport plus 4

Coolant: Dex Cool 50/50

Fuel: 100LL with Decalin

Thanks for the advice.

Jim