ORIGINAL: opjose
ORIGINAL: proptop
If it's an Evolution engine with the stock muffler, the gray gunk is probably being caused by the aluminum baffle disc in the muffler.
I would dis-assemble the muffler and and check...if that is the case, remove the disc...
Nope, that's not it.
We've verified that the gunk is not caused by the baffle.
You can substituted a different muffler without a baffle and still get the gunk.
I've done this.
Where in this thread did I miss where you "verified" that it is not caused by the baffle? I've seen more than a few Evo engines...have several of them myself...and the alum. baffle disc typically starts to vibrate and fret inside the muffler, causing a LOT of gray schmutz to come out the exh. and some of it gets into the pressure line.
On my .46's I quickly replaced the muffler w/ an Aquacraft/Tower .46 muffler and the gray goo stopped appearing.
I have no unusual wear patterns on the backplate either...?
Maybe I missed a previous thread by the O.P. where he said he'd removed a baffle or something?