YZ400/450F Top Gear Ratios?

Does anyone know what the ratio of top gear is for both the 400 and the 450?

The reason I need to know is I have an 89 TZ250 chassis and both engines available to me. The 450 engine is on a shelf in my garage and the 400 engine is in my dirt bike. I got the 450 engine for the TZ chassis before I realized it only has a 4 spd tranny, which has me wondering if I should put the 450 engine in my dirt bike and use the 400 engine in the TZ. Any help would be greatly appreciated.

What year 450?

2003 450F vs 99 400F

The '03 has a Primary Ratio of 2.818, and a top gear of 1.050, for an overall top of 2.96 at the output shaft.

The '99 has a Primary Ratio of 2.952, and a top gear of 0.952, for an overall top of 2.81 at the output shaft, making it about 5% higher geared. Taking two teeth off of the rear or an equivalent, would even things up.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now