2013 pro rmk 800 not running right

[awsome al]

Ok buddy bought a 2013 pro rmk 800 and its not running right sleds been sitting since 2015 and it misses on one cylinder he pulls that coil wire off spark plug a little and it runs better but still kinda misses. I compression tested one cylinder at 60 psi and other at 90 psi so im thinking maybe power valve stuck open or something from sitting. Thanks for help

 

[Tunneltwister]

That compression seems low, even for the 90. how many miles..?

 

[mtncat1]

you need to redo the comp test 90 psi is low 60 psi will not fire a plug at lower rpm. p/s a power valve has no effect on compression.
if the comp readings hold its a piston or maybe a reed valve issue

 

[Octanee]

60, is way low, 90 is low too, also I've had issues with my plug caps, they do wear out.... So could also have worn caps too.

 

[Hansen13]

Redo compression test, engine cold, throttle wide open. If you are still reading those numbers you need to start with at least a top end. Have your cylinder tested as long as the coating is still good, make sure it's still within spec. And a new set of pistons (good time for a fix kit). That sled won't run worth **** with compression like that. And even if it does, I wouldn't expect any longevity out of it. Soon as mine even get near 110 psi it gets opened up and freshened up.

 

[Rush600guy]

Yeah I just did a swap on my 600, got sent a lemon motor 120psi/50psi. Got a refund for bad cylinder to which I sent in my cylinder for a remanned. The returned remanned cylinder was sh*t, sitting at 100psi, and now the good 120psi cyl does not run... scratching my head, rechecked everything (good)... my guess is can only be due to compression psi offset. Sending mine in for a fresh rechrome.