dick seiders
Well Known Member
Ok,I am back with an old problem. A few months ago I experienced a stange noise in engine shortly after taking off and leveling out. The sound is what I would guess to be an ignition aberration ( I call it burp).. It gets your attention. I talked with VAF and most opinions were unbalanced prop. I did the whole digital level fix and long story short got the blades w/i 1 degree. In the course of this effort the engine noise did not repeat. Therefore, prop was the cause. A couple guys at my home base said it's the Soft Start Module take it off!. I didn't do that as it seemed unecessary.
Flew yesterday and got the sound back again after takeoff and turning left C.wind. Flew the pattern for awhile and it burped once or twice so I landed and looked at things. Saw nothing so took off again and engine performed well, maybe a tiny burp one time on downwind. I figued it's fine.
This am I took off (run ups normal, and getting 5030rpm wot static). I lifted off and climbed to about 60 ft and engine sound was back in full and also a slight loss from full power. I quickly looked at runway left to see if I could abort and did managing to set the 12 down with about 1500' to spare. I pulled the top cowl and checked all and found nothing. Took off again and at about 80' the noise was slight, but back, and by now I am a little unnerved so aborted again . Pulled the cowl and disconnected the Soft Start relaxed a bit and went out to try again. The field temp. was 97 degrees and while I was doing two or three run ups one of the banks of cyl temp. climbed into the red at 248. Likely I caused that with all the ground testing in such high temps. In the course of run up testing I did note that even with the throttle locked the prms would vary from 4080 to 3990 and back w/o killing either ignition. What's with that? The run up checks however were w/i 120 rpm of A & B ignitions as one would expect. Following this with the high temp on cyl I decided it was a good time to put the thing away. I don't think I have a fuel problem as tank had 16 gal. tested sump on gascolater and it was full. Carb. sync is good. I also installed a new set of plugs about a month ago when having a similar problem. Maybe I need to replace the Rotax ign. module?? Would really appreciate help so I fix this and get back to flying where I can go futher than half the runway length. Thanks in advance, (I know I haven't tried since removal of Soft Start Module, but will before changing anything else).
Dick Seiders 120093
Flew yesterday and got the sound back again after takeoff and turning left C.wind. Flew the pattern for awhile and it burped once or twice so I landed and looked at things. Saw nothing so took off again and engine performed well, maybe a tiny burp one time on downwind. I figued it's fine.
This am I took off (run ups normal, and getting 5030rpm wot static). I lifted off and climbed to about 60 ft and engine sound was back in full and also a slight loss from full power. I quickly looked at runway left to see if I could abort and did managing to set the 12 down with about 1500' to spare. I pulled the top cowl and checked all and found nothing. Took off again and at about 80' the noise was slight, but back, and by now I am a little unnerved so aborted again . Pulled the cowl and disconnected the Soft Start relaxed a bit and went out to try again. The field temp. was 97 degrees and while I was doing two or three run ups one of the banks of cyl temp. climbed into the red at 248. Likely I caused that with all the ground testing in such high temps. In the course of run up testing I did note that even with the throttle locked the prms would vary from 4080 to 3990 and back w/o killing either ignition. What's with that? The run up checks however were w/i 120 rpm of A & B ignitions as one would expect. Following this with the high temp on cyl I decided it was a good time to put the thing away. I don't think I have a fuel problem as tank had 16 gal. tested sump on gascolater and it was full. Carb. sync is good. I also installed a new set of plugs about a month ago when having a similar problem. Maybe I need to replace the Rotax ign. module?? Would really appreciate help so I fix this and get back to flying where I can go futher than half the runway length. Thanks in advance, (I know I haven't tried since removal of Soft Start Module, but will before changing anything else).
Dick Seiders 120093
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