speedometer is off by 5mph?

i own a 01 vfr800 and my speedometer is off by 5 mph at all times. when im doin 40 it says im doin 45. i adjust to it no big deal, but now my tach is off. it says im puttin more miles on my bike than i really am. any help?

 

Motorcycle speedometers HAVE to be off. Some states / countries / jurisdictions require that speedometers can read up to 10% high but ZERO percent low. In other words the speedometer can never be allowed to read low.

When a motorcycle goes into a turn the tires start to run on the side instead of in the center. This effectively causes the radius of the tire to be smaller, which in turn causes the speedo to read low. If you ever find a motorcycle speedometer that reads right when going in a straight line you can be assured that it will read wrong in a curve. It doesn't matter whether the speedo is driven from the wheel or the transmission either, they all make the assumption that one revolution of the tire equals "xx" inches (or feet or meters or something).

The odometer on mine is dead on the money. I rode 518 miles by GPS yesterday and my odometer recorded it as 517.3. That isn't the first time I've checked it either, it has always come up agreeing with my GPS within 1 or 2 miles. I do admit though that most of the trips I've checked it on have been on the interstate so there was no serious leaning involved. It should follow that riding on the sides of the tires in curves affects the odometer as well.

 

NORMAL .... nuff said ...man of few words .... I dont like to carry on about the things that can be said in a few words .... that is why Im just going to say 'Normal" and go about my way. If someone wants to argue the "normal" point it is their First Amendment right to do so but I may not respond and invoke my 5th amendment right.....

 

As Scraig stated, speedo's are always off on bikes usually. Common to have 8+MPH off at 80 or so. If this is not your bike from the start, you could still count your sprocket teeth (front and rear) and see if they are indeed stock.[/QUOTE]

Myth confirm, I just test out with my new GPS this morning and the Speed shown on the bike is 88 mph, The GPS shown 80mph. The distance shown my trip on the bike is 49.8 miles and my GPS shown 48.2 miles not much diffrent.

 

Normal. Mine is an '07 and the speedo is optimistic. I found this out when I had my GPS unit on the bike which shows your speed. The bike speed was off by about 5mph.

 

thanks for all your guys help. i was always comparing my speed to a vehicle next to me but yesterday my buddy got a cbr 600 and when riding, his bike does the same thing. i guess i was just freakin out. thankyou everyone.