Hello, i have purchased a 2003 cbr 600 f4i recently and the speedometer is off by a certain amount i tested against 2 other motorcycles and one car. When i am actually doing 40 it will say im doing 48 mph. Can someone help me with this!? please and thank you!

 

You can get a speedo healer to correct it. I'd bet you dont have stock size sprockets.

 

74 demon nailed it - sprockets. Even with factory sizes it will be slightly off but the smaller the front and larger the rear the higher it will read. Larger front smaller rear will make it rear slower.