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Rough running under load at high RPM

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Re: Rough running under load at high RPM

Postby mikew » Thu Apr 11, 2019 4:49 pm

Thanks Mike, worth a try, will take a look over the weekend
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Rough running under load at high RPM

Postby Ican » Thu Apr 11, 2019 5:49 pm

In my case changing the needle jet solved the problem.
What l have to mention though is that after l moved my plane from an airfield at 1800 ft to one at 5000ft, the problem manifested. It generally became worse when flying cross country at flight level 085 or 095. Obviously there is less air up higher and the engine started running rich.
Also keep in mind that the density altitude at my airfield generally hovers between 6000 and 8000 feet.
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Re: Rough running under load at high RPM

Postby skypics234 » Thu Aug 08, 2019 3:49 pm

I have found on all three of my Jab 2200s that the 245 jet is a bit too rich especially when OATs are up in the 80s F or more.

Under full power climb out I would read 2750 and the engine would run rough. I would turn my vernier throttle slightly to reduce power and the RPM would pick up and the engine ran smooth. So I changed to a 240 jet and no issues.

I'm in SoCal so it can get hot. In winter months I switch back to the 245 Main jet.

Of course, if you have a leaning device you can keep the 245 jet and then lean out slightly on a hard climb to confirm that it is too rich.

Of course, all this can vary depending on how you have your prop pitched.

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