Looking at a Ranger with an �03 Yamaha 250. Compression is 100, 100, 90, 100, 90, 100. I know you want them all to be within 5-10 of each other but is the 90-100 good?

You�d have to know the exact way the procedure was done to answer your question.

There good if there with in 10%

Compression numbers tell you a little bit....

What are the other indicators?

was the motor run to warm temp before checking if not time was wasted.

This I do not know but will find out!

Also was the throttle held open all the way.

A leak down test is a better indicator of motor health

What is this test, I�ve not heard of this before?

I�ll find out!

I can just tell you that I have dealt with two used motors that had perfect compression when I bought them, and ended not being completely mechanically sound. I am in the process of rebuilding the second one, and found that all of the lower rings were stuck in their grooves, but the upper rings were fine which is why it was still able to make good compression. Anyways, other important things to look at in my opinion are the hours and how was it taken care of.

Thank you!!!

How does it run? If it performs right, buy it and always and I mean always run a carbon cleaner in this motor. Techtron or Ring Free +, or yes Sea Foam in the fuel.

Gary, have not taken the ride yet but hope to shortly. That is for the advice!!!! It is welcomed.