For the record, the stated HP may be 48BHP from Honda, but rest assured, that was always very optimistic. The more real world number is likely to be high 30's or very low 40's actually.
I realize the licensing bureau will only base their registration on manufacturer documentation, but perhaps you could find a local dyno to produce a graph of the bike to demonstrate its real status if this issue becomes tenacious?
Richie, Cal is spot on about the actual figure being nearer to high 30s or low 40s but not about the manufacturers figure being optimistic.
Back in the day, most manufacturers gave the BHP at the crankshaft and not at the rear wheel.
If you took a CB750 rated rated by Honda at 67bhp, you would be lucky to see 55bhp at the rear wheel on a rolling road type dyno.
Here is Wikipedias explanation of the two systems.
Engine dynamometer[edit]
HORIBA engine dynamometer TITAN
An engine dynamometer measures power and torque directly from the engine's crankshaft (or flywheel), when the engine is removed from the vehicle. These dynos do not account for power losses in the drivetrain, such as the gearbox, transmission, and differential.
Chassis dynamometer (rolling road)[edit]
Main article: Chassis dynamometer
Modern roller-type chassis dyno systems use the "Salvisberg roller",[5] which improves traction and repeatability, as compared to the use of smooth or knurled drive rollers. Chassis dynamometers can be fixed or portable, and can do much more than display RPM, horsepower, and torque. With modern electronics and quick reacting, low inertia dyno systems, it is now possible to tune to best power and the smoothest runs in real time.
Other types of chassis dynamometers are available that eliminate the potential for wheel slippage on old style drive rollers, attaching directly to the vehicle hubs for direct torque measurement from the axle.
Motor vehicle emissions development and homologation dynamometer test systems often integrate emissions sampling, measurement, engine speed and load control, data acquisition, and safety monitoring into a complete test cell system. These test systems usually include complex emissions sampling equipment (such as constant volume samplers and raw exhaust gas sample preparation systems) and analyzers. These analyzers are much more sensitive and much faster than a typical portable exhaust gas analyzer. Response times of well under one second are common, and are required by many transient test cycles. In retail settings it is also common to tune the air-fuel ratio using a wideband oxygen sensor that is graphed along with the RPM.
Integration of the dynamometer control system with automatic calibration tools for engine system calibration is often found in development test cell systems. In these systems, the dynamometer load and engine speed are varied to many engine operating points, while selected engine management parameters are varied and the results recorded automatically. Later analysis of this data may then be used to generate engine calibration data used by the engine management software.
Because of frictional and mechanical losses in the various drivetrain components, the measured rear wheel brake horsepower is generally 15-20 percent less than the brake horsepower measured at the crankshaft or flywheel on an engine dynamometer.[6]
