Only the Dual Spark (DS motors) are air cooled. This includes the Monster line, Supersport Line, SportClassics, and the MH900e, as well as some of the older sport bikes (pre 916). The 916, 996, 998, 999, 1098 are all watercooled.
the DS motor is a 90 degree V-twin that is air/oil cooled and has a massive oil cooler on the front of the bike. If you look at the bikes that have this motor most are naked bikes and there is a lot of room in the frame to allow air flow. The few faired bikes (full fairing SSes) use the inside of the fairings as ducts to direct airflow to the rear cylinder. Overall though that oil cooler plays a big role in cooling the motor down. operating temperature for a DS motor runs about 173-235 degrees (they have an oil temp gauge) in average stop and go use. The overheating warning kicks in at about 335 degrees. I got caught in traffic during the 9/11 ride and saw as much as 315 on my bike which was nerve wracking but not unsafe. Overall they work like any aircooled motor - cylinder fins and a good oiling system, and very loose tolerances in the engine.
The K0 I completely lucked out on. I have a friend who is big into the DOHC bikes but hates the SOHCs (not fast enough he says). He is also completely internet and computer phobic, so he has no idea how out of control the prices on these bikes are. He was also my local parts guy at my honda dealer until last year so I know him pretty well. Anyway one oh his distant family relations had this bike on his farm upstate in a barn and gave it to him when they needed the barn cleared out. He took it in and got it running, cleaned the fuel tank and that is as far as he got before his garage got to small because of DOHC stuff. He offered to me for free if I could get it out of there and I agreed to it sight unseen. In the interm his only transportation, a 1979 cb750F spit its timing chain and took out the motor. As luck would have it another friend had a good running DOHC CB750F that a customer of his fried the wiring harness trying to jump the bike off a car battery and just wanted it junked. As a gesture of good will I bought the DOHC 750F (cheaply) and am giving it to my friend in exchange for the K0.
I have since seen the bike and While it does run, everything has a nice patina of rust on it and all the cables are frozen. It was also cafe'd in the 1970s and has some interesting parts like lester mags with dual disc, an RC cam, and accel coils. I am not 100% sure what I am going to do with the bike yet but I am leaning toward building a Joe Bar cb750 cafe racer Replica.
For those unfamilar, Joe Bar is a French comic book about four cafe racers in the 1970s who hang out at Joe's Bar. One rides an h2, one a Norton, another a Ducati 750SS, and a Red K0 cb750. I have been using the comics for the last year or so to help myself learn french and I think it is really funny. Recently a friend of mine gave me a figurine of the cb750 and it has been on my desk percolating cafe racer ideas. I just so happen to have a red body set for a K0 in my garage, so.....
one of the albums has been translated into english and you can get them from the UK:
http://www.comicsworld.co.uk/JoeBar/Albums.aspxfigurine:
http://cgi.ebay.fr/Figurine-Joe-Bar-Team-Edouard-Bracame_W0QQitemZ160158293820QQihZ006QQcategoryZ32645QQssPageNameZWDVWQQrdZ1QQcmdZViewItemhttp://cgi.ebay.com/BNIB-1-18-HONDA-CB750-JOE-BAR_W0QQitemZ130154192526QQihZ003QQcategoryZ10460QQrdZ1QQssPageNameZWD2VQQcmdZViewItem
