Dads wondering what plug type to use in his 06 4rt? the plug is always very black as if the bikes rich or do you think a different plug is needed. I think the standard was a 6 but he has been using a 5 recently but its not made much difference. May just be this is how they all run though?

Thanks for any help/info

Just

I used to have the same problem, it soots up bad if you dont let the bike warm up. Start the bike and let it idle for 5 mins with no throttle whatsoever, since i started doing this my plugs have been fine. I run the standard 6!

NIRIDIUM PLUG! it's a bit more money but worth it, they seem to never foul and are designed for low revs at long periods of time and not foul!..................john