When I'm going 55 MPH (according to the speedometer if it correct) I'm tacking about 2900 RPM's. Can anyone venture a guess on what gear ratio I have? Thanks

you'll need to tell us what size rear tire you have...

Raise the rear tires off of the ground. Mark the drive shaft so that you can count the revolutions. Mark the tires so that you can count them too. Turn the tires exactly one full turn and count the number of times the drive shaft turns. BOTH tires MUST turn exactly one turn. If the drive shaft turns 4 1/2 times it is a 4.56. If it turns just over 4 times then it is a 4.10. If it turns 3 3/4 times then it is a 3.73. If it turns 3 1/2 times it is a 3.55....