A good friend of mine used to be a Bridgestone dealer.  He race kitted a 90 Bridgestone, went like stink, and weighed nothing.  He then fitted a 100cc barrel, and it went faster.  The only setback was if it was used for motocross, the swingarm couldn't handle it, and bent at the shock mounts.  I checked out his place a few months ago, he still has the 100, plus another 90 Bridgestone stuck under the house.
I had the rare priviledge of racing a 350 Bridgestone at the Qld beach(sand) racing titles in Mackay many years ago.  It was a beautiful machine, it won the 500 class easily.