well when the 2007 Vulcan 900 is only making a paltry 40hp, double disks are more of a luxury item, where as my kz1000 was about the same weight and was running almost 100hp. and you can bet your backside parts are getting harder to get. there are times where you have to make, modify, or retrofit other parts to keep these things on the road. the gs650g was the hardest to find parts for since it was only made for 3 years, and didn't share many parts with the other gs bikes.
Thanks, very interesting.
Now I see why so many people have adds in the classifieds offering free removal or offering cash for parts bikes. The parts are worth more than the bike as a whole.