On my 720 pick up I used to have to partialy block off the radiator.......during the chilly Vegas winter. I wouldn't get any heat till I was almost to work.

As for over cooling on our Yamaha D-Sports Racer we blew 2 engines not relaizing the motor was over cooled. A friend at one of the driving experiances gace me a huge C&R radiator, sometines the motor would run as cool as 155 F, well at 12,000 RPM's the #4 rod would weld itself to the crank. I found pieces of the rod small end inside the transmission, one curly Q noodle looking small end actuall wedged itself under the started.........a call to a racer I knew who was the engineer for Yamaha's Superbike program is how I found out the problem was overcooling.

Tom