Honda's 500 Four

HONDA'S 500 FOUR

DAN HUNT

Much Like The 750 Four, It’s Less Of The Same, But Better For Some.

STAR OF HONDA's lavish preview of 1971 models in San Diego was a scaled down version of the now-classic 750 Four. Displacing 498cc, the new "500 Four" is smaller, lighter, lower and shorter than its big brother. This will appeal greatly to riders of small stature who found the weight and the seat height of the 750 hard to cope with. While no weight figures have been released by Honda, the CB500 should weigh about 80 lb. less than the CB750, if you take into account a reduction in engine dry weight from 186 lb. to 156 lb. and a corresponding reduction in the weight of frame and rolling gear components.

As the 750 weighs in at 499 lb. wet, a good guess for the 500 would be about 420 lb., about the same as the CB450 dohcTwin.

The weight factor alone should make the Four a fabulous handler, considering the remarkable road holding and agility of the bigger machine. Wheelbase, at 55.3 in., is 2 in. less than the 750's, which should quicken response to the rider's manipulations. At last, a four-stroke with the added magic of four cylinders in a size that invites throwing it around in the curves with wild abandon!

Following a basically similar pattern of the 750's, the powerplant of the 5-speed sohc 500 is built on a five main bearing crankshaft, with outer crank throws opposed to the inner two by 180 degrees. Plain bearings, lubricated by 60 psi

flow, are used to support all crankshaft, connecting rod and camshaft friction surfaces.

Notably different is the bore-stroke ratio. In the 750, it was a slightly "uhdersquare" 61 by 63mm, departing from the usual oversquare practice, as the designers had to take into consideration the width of the large capacity engine. In the 500 Four, the engine width is inherently less, so that bore need not be restricted. If anything, height must be a consideration in what Honda wishes to be a low-profile machine. For whatever the reason, the bore/stroke ratio is now 56 by 50.6mm, or slightly oversquare.

Quoted horsepower figure for the 500 is 50 bhp at 9000 rpm, taken at the transmission output shaft, compared to the 750's 67 bhp. With a 150-lb. rider aboard, the lb./bhp for the

500 (if it weighs about 420 lb.) is about 11.4, making it somewhat less potent in terms of relative weight than the 750, which has a Ib./bhp figure of 9.7. As the 500 has slightly more poop than the 45-bhp dohc Twin, with similar weight, you can expect the new Four to move out somewhat faster than the Twin.

Our guess would be quarter-mile times in the low 90-mph bracket, with elapsed time between 13.8 and 14.1. Top speed will probably range from 104 to 110 mph.

Another item which makes the 500 different: lubrication is by wet sump, eliminating the oil tank used on the dry sump 750. This, to a small extent, lowers the center of gravity, as well as making a neater engine package by eliminating all external oil lines. It is also advantageous for cooling the oil supply, due to the fact that the increased surface area of an under-engine cooling reservoir dissipates heat faster than the typical external oil tank.

The four carburetors on the new 500 are of slightly different design, enclosing the bell cranks on which the throttle cables operate inside the carburetor bodies. This offers increased dust protection, while obviating the need for the rubber seals on the 750's exposed bell crank linkages. The new carburetors are PW-22 (mm) Keihins.

Otherwise, the same good things one finds on the 750 are found on the 500: electric starting, hydraulic disc front brake, and four snappy looking mufflers, which proclaim its multitude of cylinders. *

The bike has a new tank decor, with two-tone coloring and double pin-striping which echoes the shape of the Four's header pipes.

An easy-to-read instrument panel on the handlebars displays four clearly labeled "idiot" lights to apprise you of the operating status of your turn signals, oil pressure, headlight high beam and when you're in neutral.

Best news is that the bike will cost less than the 750 Four. No official price has been given, but the best guesses put it somewhere between the 750 and the 450, which would be in the $1200 range. If you advocate a brisk performing yet compact machine, you may find that the 500 Four is a good alternative to the 750, no matter what size you are. [§]

HONDA CB500