Exhaust residue - is this normal?

[droy]

Pulled off the headers off my Skorpion Sport (51,000km on the clock) and looked at the exhaust valves. I have .5 to 1mm of yellow power residue on the valve stems. Running to lean?

BTW - Original owner, jet kit, foam air filter and custon Barker headers are the only engine mods.

[jimc]

I think the plug electrode condition is a better indicator of rich/lean.
Regarding the yellow stuff on the exh. valve stems, some things to look into..
Does the bike use any coolant? maybe pressure check cooling system & do a cylinder leakdown .or maybe switch fuel brands . Possible you have a marginal head gasket seal.
Good Luck

[DAVID THOMPSON]

droy what is your country

the quality of the gas may be the cause
it may be sulfur build up if sulfur content high in fuel

the high heat at valve may make it collect...
it is a bright yellow
almost the color of the yellow used to paint road lines

ar dave