top end

Arnold

New Member
Jun 29, 2012
317
8
18
Brattleboro, vt
so I polished my ports last summer and raised my exhaust port 1 mm. this is the first time I have had a chance to look at it since I put it back together. this is with about 20 hours of ride time here is a few pics

8194-top-my-piston.jpg


8195-head.jpg


8193-my-polished-exhaust-port.jpg


one question though, on the top of the piston I have two lines in the carbon tha line up with the edge of the transfer ports. now there doesnt seem to be any damage that I can see so I was just wondering what it was from or if its a sign of something

thanks
arnold
 
They are possibly signs of fuel wash as the fresh charge enters the combustion chamber.

If the area around the exit of the exhaust port shows no sign of deteriation, dimpling or frying, I would say it all looks fine.
 
Some of it might also be type of oil. Best clue is the underside of piston dome. If you have a lot of burnt oil it is lean, but it might not be the main jet, could be mid range as most of us aren't WOT all the time.
Because a 2s doesn't have the dead stroke a 4s has to cool off, the only thing that really cools the piston is the incoming charge both above and below the piston.
I too am still learning things, and I've been at it awhile.

And IF you decide to remove the piston to look, I HIGHLY recomend using new piston pin C-clips.