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Motorcycle Repair/1999 cbr 900rr


My speed odometer is off by I think like 10 mph I've replace the electronic piece that go's in the motor cause the speed odometer stopped working now that I've replaced that part it work again but my mph is off how can I adjust or fix this issue thanks

Hello David.

All speedometers have a reading "error" of 3 to 6%, depending on the manufacturer.
The CBR is on the high end of 5-6%.
As you can understand, that's proportional to the actual speed, and always "optimistic", meaning that when you ride with 50mph the reading is 52-53. At 100mph it shows 105-106 and so on.

What I need from you is to clarify: a)at what speed does the 10mph error occur, b)is it higher or lower than the actual speed, c)if the final drive is altered (sprockets number of teeth) and d)if your rear tire is of standard dimensions.

If your final drive and rear tire are stock and the error is off-limits, two things can be done.You either install an aftermarket speedo correction module (like Healtech's Speedohealer) or find a vehicle electronics "hacker" to adjust your speedometer.

You can also test your speedometer a simple way. Use a GPS to measure not the speed, but the distance driven. Reset both the GPS and the trip counter of your speedo and compare the readings after a 5-6 mile ride. The reading error apply mostly on the speed and less on the distance.

Closing, I must say that in some states (not sure which) as in many countries, the error must be at least 4% by law.

Feel free to get back with more info, so I can guide you more accurately.

Best Regards,
Lazaros Ampatzidis.

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Lazaros Ampatzidis


I can help you on EVERY issue involving POST-1980 Japanese Motorcycles plus KTM and Husaberg. My field of expertise includes Engine, Transmission, Fuel system (carburation & EFI),Electrics and Electronics. Maintenance, repair and tuning. Road and off-road suspension tuning. Please don't ask me about non-Japanese Motorcycle, especially American built on which I have low to zero experience.


I'm a rider and hobbyist since childhood. 25 years motorcycle workshop mechanic.15 years motorcycle racing mechanic. In order of experience high to low:Kawasaki,Suzuki,Honda,Yamaha,KTM,Husaberg.

Hellenic (Greek) Technical School.Internal Combustion Engines Engineer. Automotive Electronics.

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