2003 Polaris Predator.  Owner brought it to me with fueling issues.  Bought the bike with a Edelbrock carburetor which had no choke...he complained about cold-start issues.  He bought a new stock carburetor for it and it wouldn't run at all.

I got it and found a number of issues...leading the way with <55lbs of compression.  I pull the top end off to inspect the piston and cylinder.  Cylinder is clean, piston is clean, there's a little wear on the rings but not near enough for me to consider it an issue.  I didn't see anything that said "this is the problem".  I don't specialize in 4-strokes, though...in fact, I only took this one on because it's a friend.  Looking back at my pictures (I document every tear-down), it appears as though the cams are one tooth off.  I wanted to test this without having to put EVERYTHING back together so I just torqued the jug and head down with good gaskets, held the cam chain on a pulley, and started cranking...got 45lbs.  Would not having the cams installed effect compression?

damn...my ass didn't even get off the chair before I realized she wouldn't be breathing at all.  I hate thinking about something so hard for such an obvious, simple answer...

im guessing that with an Edelbrock carburetor its also running a BBK?  most predator owners dont do the carb without having the BBK installed along wiht hot cams.  i would guess cam timing is off.

whats the bore size?  also have you check to make sure valves are in spec?

it's a polaris....RUN AWAY

yeah and the timing marks suck
and to check it you have to rotate the damn thing something like 21 revolutions to get the timing marks to line up for the second time.
Polaris mechanics don't want to work on them

It's actually got a spiffy timing mark system that's completely baffling to me.  I just put the cam gears in right an time the crank...bam! 90 psi (low, to me, but that's factory spec).  If a polaris mechanic ever does get the bike he'll be lost.

I hate Polaris, though.  I won't eve work on a smoker, much less ones with valves.  I only did this one because the owner is a friend and he does a lot of machining for me.