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Black Spark Plug

Posted: Thu Aug 14, 2014 9:22 am
by Tabian
Hi, after my tea time run of about 60 or 70 miles the spark plug is really sooty, can anybody tell me how to cure it please...?

Re: Black Spark Plug

Posted: Thu Aug 14, 2014 10:05 am
by bristolmod
Clean it? :D

I think you may need to tell us your set up first...............

Re: Black Spark Plug

Posted: Thu Aug 14, 2014 11:21 am
by Tabian
GP200 with 22mm Jetex carb

Re: Black Spark Plug

Posted: Thu Aug 14, 2014 11:39 am
by bristolmod
Jetex could be the problem- poorly machined?

Main jet to large? Try 118

Jets/ atomisers/ slide. Wrong sizes / poorly made?

Wrong spark plug?

Blocked air filter?

Is bike running OK apart from black plug?

Re: Black Spark Plug

Posted: Thu Aug 14, 2014 12:20 pm
by Tabian
Main jet is 118
spark plug Champion N5C for hot running
air filter looks a bit iffy
but apart from that it runs quite well

Re: Black Spark Plug

Posted: Thu Aug 14, 2014 1:16 pm
by bristolmod
try an N4 or a genuine NGK B7ES