Honda produced the 650 cc (honda service manual claims 627 cc, although "626cc" cast on motor) series inline four cylinder overhead cam street bikes as their last line of SOHC bikes made. It makes decent power for the aging SOHC technology and is still a sharp looking roadbike.
Below are the model variants as listed in the Haynes repair manual. While produced in the US until 1982, it appears the SOHC 650 continued overseas production until early 1984. I have also heard of a Japanese model, the CB650LC JAPAN, with a "Luxury Custom" emblem side cover. Maybe the luxury model didn't vibrate like hell at 70 mph or blow headgaskets. :)
The standard model had spoked rims, single front disk brake, and 4 into 2 exhaust. The custom models had comstar rims, dual front disk brakes, and 4 into 4 exhaust. The 1982 CB650SC was the Nighthawk, and had redesigned body paneling, a different seat, a black powder coated engine, and dual brake calipers in the front. Of course, there were many more changes, like the gas tanks, colors, forks, gauges, etc., I will eventually try to document them all. The engine itself went through no changes from '79 to '82. The gearbox had very slight changes, they are listed in the performance specs section.
Gearbox Ratio Chart:
CYLINDER HEAD IDENTIFICATION:
O.K, this is kind of tricky. Evidently there are in fact two different cylinder heads used on the 650. I can't imagine why, I never thought this was true until I looked up the part numbers. I'm guessing that they did it to better accomidate the CV style carbs, although you'd think they would have just molded new rubber manifold insulators? Why Honda would go through the trouble and cost to recast the head is beyond me, but maybe there are other differences. I'm assuming that the reason the '82 nighthawk casting has a unique part number is because it was painted black, and is in fact the same version as the '81 and up silver heads were. Please help me fill in the blanks below so we all know what's going on.
Custom and Nighthawk specifications are the same as the Standard Model unless otherwise indicated by a C=(Custom) or SC=(Nighthawk). I
believe the U.K. models at one time used the VB54 carbs, info on this would be appreciated.
TIRE SIZE IDENTIFICATION: