I rode one hot summer night (1972) with a guy who had one of the old Indian Fours, but much-stripped, sort of 'chopped' but with normal front end forks (just skinny fenders). Along about 11PM I was riding next to him and noticed the rear 2 cylinders were actually glowing a little bit, and you could see a shadow of the last piston moving up/down as we rode! Later I asked him about "length of ring life" and some other pointed questions: he said it was mostly that he worked on it half the winter, every year, to be able to ride it 2 months in the summer. He'd put new rings in it several times. He had owned it for more than a decade then. He mentioned that he had hopes that the new, slimmer front fender would help cool it better. That made me wonder what the engine looked like at night with all the fancy Indian stuff on it?