Sorry guys, been away a coupla days. Thanks for all your input.
Bill, when I was getting 6700rpm on climbout it was never overheating. All this trouble seemed to happen around the same time. The Rads have been cleaned and checked by a pro with an endscope cam and he said its ok.
Dennis. You said.... If the engine will pull 6250 static and only climbout at 6100, what is happening? The load on the engine is decreasing as forward speed increases,the rpm should be coming up. Thats what don't make sense. I guess we need to look at a cause that could produce that symptom. Maybe timing? I would have to call in a rotax mechanic for that I think. The engine does start super fast (sugesting timing retard) since I had the Stator Plate replaced a while back, and before that, there was no overheating. It all seemed to start one week before the stator was fitter, because I remember they Rotax guy saying the new stator might fix the problem, but it didn't. IF the old stator caused bad timing...and the new one was not timed properly... then that could be an issue yes?
Today I did another test... this time with the cowling on, and Static was 6400rpm and climbout still 6100. Checked blades again to be normal after flight. Also did a WOT during taxi back and it was still only 6100rpm. It was much cooler today though at only 64 deg.
I done nothing to change airflow on cowling.
No changes to the carby or air intake, but I did try a larger main jet (165 to a 170) and it made no difference, so I changed back to the recommended 165.
No change to exhaust except a new gasket fitted when checked the pistons. No leaks I am aware of.
No change to anything prior to take off. All done exactly as with static test. Throttle pushed at same slow speed also.
I have been using a tiny tach for a few months now, and it has always read 100 rpm lower than the analogue one, so that means if the tiny tach is correct, the rpm on take off is really only about 6000 rpm.
Nick... Somehow I don't think the tach is a problem because I used to get easily 1200-1500 fpm on climbout at WOT, but now only 800rpm. So its not the tach I am sure. What I will do next will be a video showing everything from static test to climbout to cruise so you can see al;l the gauges at each phase of flight. That will be a week away though as I got a bit on at the minute and also need the weather to cool back down again.
Thanks for everything guys.... Mike
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