So my son has a 2001 Yamaha phazer 500 and at the end of last year he had to rebuild the motor. The crank bearing went out. He did a complete engine rebuild but decided to stay with the stock cylinder size. The cylinders were hone only and not oversized. New piston and rings installed. Engine it back together and he has not even put one mile on the sled due to no snow at the end of the year. I did a compression test on the motor today and see one cylinder is at 125 PSI but the other is only showing at 110 PSI. What would caused this issues and would he be ok running it like this? Older sled so doesn't want to really put any more money into the sled.
no miles on it? Put in a cap fill of 2 stroke oil and check it again. I would guess nothing is set. Also check the reeds.
odds are it will be fine once it breaks in. check the reeds but it might just have a sticky ring from assembly lube.
correct no miles on the motor. When I put the oil in should I turn it over a few times before I take the compression test?
Yes correct. Spin clutch by hand or pull slowly.