In article ,
Jeff wrote:

Every few hundred hours I've pulled the exhaust elbows from my
2GM20F's to chip the carbon away. The starboard engine in particular
has a tight turn in the exhaust hose, and since it gets used some at
low rpm for charging, it tends to get some buildup.

Might you be charging at too low an RPM for too long? Either that or you
have an obstruction (that tight turn?) or mis-adjustment. That first pic
is ugly! We have 1200 hours on our 2GM20F and I haven't found any
appreciable carbon. I rarely idle below 1200, as was recommended to me.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/