Exhaust Film on Transom??
 

Just took the boat out for the 2nd time this year and noticed
a lot of black exhaust film on the transom. It was an evening run and air temp was about 68deg. Would this be a choke issue??
I've always gotten a little but never this bad. Any ideas?

I have a 260 legend with a carb motor. I noticed the same thing this year. I think it has to do with the weather. Plus I was running the full tank from the winter. I'm gonna fill up with new gas and see if it is the same. I'll use regular as I found that high test causes more black soot. I usually put the boat away with a full tank of hi test.

Gary C. You know I just starting running the higher octane and I don't recall seeing much of any of this last year. As well as I still have a half a tank of old gas from last year. I'm heading out again today so I'm going to fill up with the mid.

Thanks Brian

Alot of it is from maybe still having the winter fuel in the tank
this fuel will not perform well in warmer weather and also the fuel is a year (almost) old ... be sure your choke comes all the way off
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And MSD 6AL and coil will relly help this (no I don't work for MSD)
its just good stuff ,leave the thunderbolt on the boat that way you have a spare :D :D :D

Well I topped it off with fresh mid grade and she came in pretty clean. I think you guys were right on the old fuel. It was in the mid 80's as well. What a beautiful day on the lake!! The first nice weekend this year.

What engines and which boat?

I've got a 1993 Conquest with a 454 mag.

I have soot on the transom every time I take her out. I just assumed it was from the carb that we have on her.
And we almost always put the higher octane fuel in her too.

So is it better to run 89 octane in a a 502 MAG MPI? I run 92 or 93.

Sure would save a little money over time....Hey, a case of beer is a case of beer!!!:D

I can only tell you this much. It came in with a dark gray transon with 93 octane with an air temp of 68deg. And with 89 octane and a near 85 edg temp she was nearly clean. I do think the air temp had something to do with it but just not sure how much??