Black residue INSIDE carb?

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todds112
Posts: 666
Joined: Sun Dec 03, 2006 5:45 pm
Location: Jackson Hole, WY

Black residue INSIDE carb?

Post by todds112 »

Took my carb apart when I got it a few months ago and cleaned them up. Today I tore everything down to install gaskets in the oil cooler and fuel pump to fix some oil leaks...anyway. The rear carb has this black residue around the inside of the throat. The front carb doesn't look like that.

What could cause that? I did switch out from the 140 to 125 main jets, but didn't adjust anything else.
1973 712M
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