I've had some issue with the Bridgestone lately, after it acted up on Sunday. It was extra strange, since it ran so good on Saturday. The problem was a bit strange, as it would get very rich with throttle, and eventually stop running. I could clean the plug, and it would fire right up again and idle fine. But as soon as I would give it some throttle, it would load up and stop again.
I quickly went through the carb and found nothing wrong, but gave it a good cleaning anyways. No fix to the problem. As it happens, I discovered I was running a NGK B8H spark plug. This is the plug listed in the Bridgestone service manual for racing, indicating it might be hard to start and foul easier. Of course it hasn't been fouling the last dozen times I've ridden it, so I'm not sure the wrong heat range of the plug was leading to the problem.
As luck would have it, NAPA actually had the correct NGK B7HS plug in stock. So after gapping it and installing it, the bike fired right up. And of course runs great now. Takes throttle, doesn't foul up, and shows no other signs of having this problem.
I'm going to grab another plug and put it in the small spares kit I'm going to keep on the bike.
For shits and grins, here is a pick of the old plug:
Doesn't look dead to me, but it sure wouldn't run!