SilverWing Tales

Background on the CX500

By: Eirik Skjeveland (

I'm indebted to Eirik Skjeveland who corrected some inaccuracies in my orginial posting (i.e., the 500 Turbo was not developed for the racing circuit). He has graciously allowed me to edit and share his messages.

Chuck Gardner

Honda did not develop a 500 cc pushrod twin for racing. They did development work on a turbo, a 250 cc with oval pistons. In fact, it was more or less 1/2 of a NR 500 engine. The reason for only 250 cc capacity was that FIM will not allow more for supercharged bikes. Problem was, as You mentioned, a trouble in controlling the power, although it did produce 150 hp so it was fast.

The development of the CX based 500 cc Turbo and the NR based 250 cc Turbo was done by completely different teams. The race version was an effort by HRC (Honda Racing Corp.), the CX by Honda`s ordinary motorcycle engineering team. The CX started as a "show off" effort. Honda wanted to flex it muscles, saying to the whole world "look what we can do!". In this respect, the project was very similar to the later NR 750.

Honda learned a lot from this bike, most of all how not to make a Turbo. A very low compression (7.2:1) combined with high turbo pressure (19.1 PSI), produced a nearly unridable bike for normal conditions. Power delay was normally 2 sec. from normal cruising speeds, and then it all came in with a bang. Off boost any old bike with more than 100 cc would out-accelerate the Turbo from a standing start. When gas flow was high enough to get the turbo spinning, usually between 4-5000 rpm under full throttle, you had to be careful not to run over any car in front of you. Overtaking demanded a curious technique - pin the throttle and drag the brakes until no oncoming traffic was in sight, release the brakes and BOOM you passed the startled car driver. Because the torque is very even on boost over the rpm range, gear selection becomes non critical. From 100 kph (60 mph), the little 500, which was heavy as an 1100, would stay with a 1100 in roll-on contests.

Since the peculiar power delivery of the 500 was more than most could handle on tight, curvy roads, Honda decided to make a better Turbo;the CX 650 T. It had, obviously, more displacement (673 cc vs. 496 cc), a higher compression (7.8:1) and a bit less turbo pressure (17.4 PSI, if my mind serves me correctly). This bike was a bit easier to ride, but not by much, because it was so powerful. In 5th gear roll ons, it went from 100-140 kph (62-87 mph) in just 4 sec! A top speed around 140 mph combined with suspension more suitable for a Gold Wing, made for an interesting ride. As with the 500 before it, the 650 was no success and disappeared after one year of production.

The engine on which the CX 500 was based, was originally developed for a small car. Strangely, the first model run produced much more power than the later ones. Top speed of as much as 116 mph (187 km/h) was reached in tests, and 0-62 mph (0-100 km/h) as quick as 5.4 sec. More normal performance level is just short of 110 mph (175 km/h) and 7 sec. The fastest CX I have tried, was my own - it would lift its front wheel on power only riding two up.

In Europe, the CX family all had twin front discs. A later model, the EuroSport, also featured a rear disc brake, Turbo styling and Pro-Link, but with only bikini fairing . The strong point in this little bike is the engine. Many people experience 100,000 mi. without any problem. Power is scarce, but delivered evenly over the rpm range, particularly the European versions.

In the end, the CX Turbo resulted in 220 new patents for Honda, witch, I think, must be an absolute record for one bike. Among others, anti-dive, turbo, "intelligent" fuel injection, street version of single shock suspension, twin-piston brake calipers and integrated fairing was all a first for Honda. None of this was unique in itself, and everything had more or less been seen before in similar configuration, but never before had so many niceties been seen put together on just one bike.

Unfortunately, Honda decided to drop the whole CX line in the end of 1983. In Germany alone, Honda sold more than 40,000 CX`s, and still they fetch abnormally high prices (the 500 is actually more expensive than the 650 there). In Norway, were I live, the CX has a very loyal following, although prices are not particularly high. But I cry when I see what some of you paid for your bikes. A friend just got a US spec SilverWing 500 from USA (they never came to Norway) without fairing, but with saddlebags and topcase. He paid NOK 55.000 for it (eq. to US$ 8.500)!!! It runs far to lean, and performance suffers as a result. An ordinary CX in good running condition cost about half of that, a scruffy bike can go as low as 1/4.

Here's more by Eirik about the GL650.

Back to: SilverWing Tales - Part 1