carbon fouling

[carbold]

Hi guys
just changed the spark plugs and noticed the R/H one is covered with black dry carbon deposits.
Mr Haynes says it could be due to
over-rich fuel/air mix
faulty chocke operation
blocked air filter
I don't think it's the last two otherwise both plugs would be in the same condition...

Any tips????

Bike is a 1999 1150GS with 10,000 miles on the clock

Cheers

 

[The Mechanic]

Black Stuff....giss a job!

Depends how bad the old plugs were in relation to electrode wear
and gap setting. Had you run the engine for a very short period of time just prior to plug removal, this can produce black sooty deposits on the plug.

Other potential causes could be:
Tight inlet valve clearance.
Exhuast front pipe leak allowing air to drawn in and raising the exhaust gas temperature considerably (more likely to show the plug colour as grey white ish.
Leaking (dribbling) fuel injector possibly due to varnishing

 

[carbold]

YES

I did run the engine for a short time before removing the plugs!!!
And used the chocke too...

Thanx Mech, I'll check them again after some more miles before warring seriously.

Cheers