2008 rmk 700 piston problems

[RMK Rider]

Went for a ride on sunday in the powder snow. On the way home was having trouble with what I thought might be snow being sucked in. Fouled a plug changed in ran good for 4 or 5 miles then same problem. Got home and pulled the plugs tried the thumb over the plug hole and found low compression on mag side did a compression test 125lbs on pto side 67lbs on mag side. Piston scored on exhaust side, piston ring wasn't seized into the ring groove just scoring on 1 side any ideas as to what could have happened. It still ran when I got home hit the throttle rev up for a short time then it would cut back in revs but go back up if you let off and hit it again. Any ideas would be great but please don't tell me the buy a doo or cat or yammy stories because they all break down. Thank for any insite to my problem.

 

[TROLLCAT]

If snow injestion caused the damage both pistons should be damage 1 more than the other in your case , no damage on the good piston then there is something else going on its EFI , more info needed

 

[RMK Rider]

Yes it's EFI. The only marks are on the exhaust side of the piston intake side looks good. The pto side piston has 2 or 3 little marks on the exhaust side on the bottom edge and thats all. Compression was good on that side 125lbs

 

[tex78]

thats tipical for the po's.... have ya had the update done?

 

[RMK Rider]

Didn't know about any updates for the 700s. Checked on any recalls through a dealer and the only thing it needed is the gromet on the oil tank and hand warmers and that was done last year.

 

[tex78]

woops it the 800's that have the updates.... what do the intake side of the pistions look like?

 

[fargineyesore]

Check the voltage regulator. I just had Elk Island Sales replace both pistons on mine because the voltage regulator failed, which controls the injectors. Sucks big time. Apparently the stock voltage regulators aren't very reliable, and they are now replacing with a different regulator. I only have 1300 miles on the machine.

 

[RMK Rider]

intake side is fine, just the exhaust side of 1 piston. will have to get the voltage reg checked when I get it back together