I have a 2006 Ranger 700 XP with 1000 hrs. My problems started from an oil pressure issue- it blew the seal on the filter, which created a knock. Took it into my local dealer, and they fixed the oil pressure relief valve, but didn’t notice the knock. They also replaced the TPS and TBAP, as well as some other things that needed attention.

Took machine home, and the knock was back, as soon as I pulled it off the trailer. Took machine back to the dealer, and they diagnosed it with a rod knock. Purchased a rebuild kit from Hot Rods (Crankshaft, pistons/rings (Namura), and all gaskets/seals. Removed engine and tore down. Cylinders didn’t appear to be damaged, heads were not warped. No metal in crankcase. Confirmed rod knock- driver side rod had obvious play (horizontal and vertical). Removed gaskets completely, and cleaned everything up (carb cleaner and elbow grease. Cleaned valve side of head, but didn’t remove or re-seat valves.

Re-Assembled engine following service manual, with the exception of replacing valve seals. Filled oil filter to 3/4 with oil, primed oil pump, and put the rest of the oil (2 qts) into engine. Filled coolant and bled system.

Engine started great. Let idle while I checked for leaks, then took it for a short drive (2 blocks, @ 10 mph). There was a cloud of smoke behind me. Slowly returned to garage. Checked coolant level and oil level, which both seemed fine. Let machine idle and noticed oil droplets on floor under exhaust.

Pulled the spark plugs and could see a small amount of what appears to be oil on piston heads, and plug on passenger side was wet. Thought it might have been oil from assembly, so put plugs back in and started/idled for 5-10 minutes. Pulled plugs again, and there seemed to be more oil on piston heads than before.

Pulled plugs and did a compression check. 140 on both cylinders. Checked oil level again, but since the oil was so clear/new, I couldn’t tell of the level dropped. Oil does not appear to have coolant in it. Coolant level is stable, and looks good- I did have to add to the reservoir a couple times, but stable since.

I’m no mechanic, but this is what I’m thinking:
1.) I have a blown gasket that is allowing oil into both cylinders, but no coolant, which seems unlikely.
2.) I have two bad valve seals.
3.) There are piston ring/seating issues. I still have the old pistons, and am considering putting them back in, with new rings.

Before I pull the valve cover and head, replace valve seals, gaskets, pistons and rings, and reassemble, I thought I would get some opinions to help diagnose.

Anyone else run into this, or have any suggestions?