Motorcycle Repair: Fouled plugs, valve seals, cb 750

Question
I have a 1982 cb 750 F that continues to have fouled plugs.  I have had the carbs taken off and cleaned numerous times.  I can only ride about 150 miles before they go bad.  What should I do?  Thank you

Brent

Answer
Brent,

have you checked the ignition advance unit?
If the timing is late the fuel may not have enough
time to burn fully, hence the dry fouling.

is it dry carbon fouling or wet oily fouling?
If it's dry, it is the fuel mixture, or plugged exhaust
or air filter.
if it's wet it is fuel flooding or oil fouling.
Is the choke okay?

Is your engine breather running into the air
filter box, this can suck oily air into the intake.

It may be bad oil rings
or valve seals, maybe, but
most likely leaking oil rings. How is the compression?

Have you tried NGK platinum tipped plugs?
They have the small electrode and are resistant
to fouling. Oil fouling can only come from the
engine, try some "seafoam" or similar in the fuel to
possibly free stuck rings. They may be carboned
up and stuck. Last resort, rebuild the top end.