I'm looking at a skeeter with a 2000 150hp vmax hpdi. How do I check the compression on this? Also, how long would you expect this motor to run strong before needing a new powerhead or rebuild. It has been used about 1-2 times a week since new, but well maintained by both owners. It still runs great and has no obvious signs of problems, I just want to know the health of the motor and enable my self to plan ahead. Thanks.