Kohler KT 17 Compression Test
 

I am wondering what would be good compression for a KT17 Kohler with unknown hours since it replaced a series I motor and dont know the true hours?I have 90 PSI in each cylinder.

From my Kohler manual:

"A difference in pressure reading between cylinders in excess of 15%, or readings below 90 psi can indicate the following: Blown head gasket, warped or loose head, worn piston rings, leaky valves, and excessive combustion deposits."

You're on the low end of the acceptable range. Did you ever pull the heads off and fix the valves? If so, you've eliminated everything but worn rings. Does the engine smoke or use excessive oil (more than a quart in 25 hours)?

Did you read the service manual when you did the check. I know it says something about having the throttle and/or choke in a certain position otherwise it'll give a false reading.

compression check
 

Throttle wide open ,same for choke.:beerchug: