In the mid-1960s, most U.S. police motorcycles were big 74 cubic-inch Harley-Davidsons. But that didn’t stop Honda, always looking for new markets, from making a play for a piece of that police pursuit motorcycle pie with the Honda CB450 Police Special.
The CP450, as it was designated, was essentially a CB450 with added features appropriate for a police pursuit motorcycle. One of the most notable features is the siren. Pulling and holding a second hand lever below the clutch on the left handlebar engages a long, ribbed drive wheel, holding it against the right side of the rear tire. The drive wheel is mounted on a bell crank that pivots when the lever is pulled in, thus holding the drive wheel against the tire. A massive cable, rather like a super-sized tachometer cable, is driven off the ribbed wheel to the back of the siren, where it spins the siren mechanism. If you want the siren to really wail, pull the lever in more firmly and the pitch increases, while letting off the pressure lowers the pitch. Despite drawing its power off the driveline, there is no apparent drop-off in speed when it is engaged. Here's a quick video demonstrating what it sounded like to be pulled over by a CP450:
Read more about this motorcycle:
• 1967 Honda CB450 Police Special