I recently bought a used Kolb Firestar with a freshly rebuilt (4Hrs) Rotax 447
single carb. I'm writing in hopes of getting some advise on getting it tuned up.
I'm a little concerned about the EGT/CHT temps I'm getting while operating
at speed. I'm getting a lot of surging and stumbling. It's difficult to find a
happy cruise RPM. Anything below 5000 RPM and it will slowly load up and begin
to lose RPM and run rough. When I try to nudge the throttle up a small amount,
I get a surge that puts me up to 5500 RPM. My EGT is only reading 850-900 and
my CHT is reading 300-325. I assumed this was indicating a over rich condition
but when I checked the plugs I found the healthy looking rust/brown color
I've seen in the books. I'm thinking that I may benefit from dropping the neddle
down one notch to lean it out and see if I can bring my EGT and CHT in line.
Does anyone have any feedback or opinions? Any help I can get will be appreciated.
-John
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