Can anyone offer me advice on myTY 250 Mono 1986.  It keeps fouling plugs.  When I remove the plug it is dry but with thick black deposits.  The bike runs well for a time but after about every 4 hours the plug is fouledand needs replacement.  Is this an ignition ot carb issue?  Any advice gratefully received.

Fueling too rich or timing too retarded is what google tells me, so could be either 😅  I always start any problem like this with a carb rebuild, because it seems that with old bikes it's always time for a carb rebuild ...

The only way an ignition system can cause carbon build-up on the plug tip is if it doesn't spark each time. If the bike runs reasonably normally, then the cause of the carbon build up is something else.

It may be the carby causing it to run too rich or there may be too much oil in the fuel or it might have a plug with the wrong heat range or it might have the wrong kind of oil in the fuel.

Edited March 15, 20233 yr by feetupfun

I would check the air filter and exhaust first.

Guy

maybe clutch side crank seal is compromised

i had that on my rev 3 it was the air mix .adjusted screw and was ok after