T

Top Cat

Well Known Member
When I first started flying my RV-12 I was using 100LL with decal in, mostly as I flew home from buying the SLSA at Vans.
The inner exhaust pipe was a brownish great with a line of white around the pipe ring which I took to be lead from the fuel.

Since then I use 93 non-ethanol mogas almost exclusively (only 3 gallons 100LL since Jan 1st this year) for the last 35+ hours and the pipe is a brownish smudge on the finger.

I've just installed new floats, had carbs rebalanced, and new carb springs installed. Engine is running very well. I think moving the carbs dealing with the floats took them a little out of balance, not much but a little.

Today the inside exhaust has more of a black sooty smudge on the finger.

So?.question is?what are you folks experiencing and is the blacker sooty smudge indicative of anything?

I ran it by my Rotax mechanic and he said when we pull the plugs at annual in July if they look okay (brownish color) then he's okay with them and not bothered so much by the exhaust color.

Appreciate any input.
 
After having flown over 160 Hobbs hours during the past 14 months (90% on ethanol mo gas), my RV-12 ELSA exhaust outlets also exhibit a light, black sooty coating on the inside of the pipes. Everything about my engine is running great, spark plugs are normal, etc. I understand that such a sooty coating is normal for 912s and reflects the effects of idling without a traditional mixture control. Sounds normal to me.
 
I operate an RV-12 that runs exclusively 100LL and one that runs exclusively 92 octane non ethanol. My good friend runs 92 octane non ethanol exclusively in his -12 as well and another friend runs exclusively 92 octane with ethanol. Both of the aircraft running the 92 octane non ethanol have a good amount of black soot at the bottom of the exhaust pipe exit that flakes off onto a finger when touched. The -12 running 92 octane with ethanol also creates black soot but seemingly not as much. The -12 running 100LL has a much less amount of soot of a slightly lighter color. That's my experience. What you are experiencing sounds normal.
 
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