Oh, no worries! I would've assumed it was identical or at least very close. As it turns out, there are more differences that I wouldn't have thought of.
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That might explain why your top speed was so low. The clutches may not have been able to shift out fully with the heavier weights.So, the primary had weights for 0-2000' elevation.....just ordered ones for 6-9000'.
There is no wash on that piston, exhaust side seize, intake mostly clean, I don't see any detonation (will erode the exhaust edge if that's the cause). For an overheat condition, I would expect intake to be seized up much more than that, I'd expect oil to be burnt onto the underside of the crown (it's clean) and you usually see minimal to no oil on the wrist pin bearing (it has a ton of oil). So not oil shortage either. It burned down lean (unfortunately I have experience on lean burn downs...).
How did the other piston look? Any pics? Was the wash good? Etc? That will tell you how your jetting is. If the other piston has minimal wash, that could do it. Also, mag sides often require more gas as the magneto runs them a bit hotter...and sometimes one cylinder just likes a little more gas due to variation in manufacture.
That said, I am suspecting a leak of some type on that side. Intake boot? Intake gasket? Exhaust gasket? Crankcase seal? Crankcase gasket? Something made that side run too lean. Was it "loud" due to bad exhaust donut?
And a tip for your first time back out, watch the pre-mix. That actually leans you out a bit because the fluid/gas is more viscous. Yes, you have more oil...but oil is not your issue here. And it's a good idea to run a bottle of octane booster just to keep temps down a little more when breaking it in...I use Royal Purple after many trials. Is available everywhere and works well. Is just an added safety measure.
No. The MAG side and the PTO side are right and left side references. The Exhaust side and Intake side are front and back side references. There obviously is a MAG side or PTO side piston, but that does not describe where on the piston that the ring failure occurred.The arrow on the piston should point to the mag side of a Polaris, yes?
The problem with removing the oil pump, is that the critical PTO end crankshaft bearing does not get oil directly injected onto it. Instead, it is blocked from receiving oil from the fuel stream, by the bearing that occurs next to it. In the Polaris model years after 2000, Polaris thought that they would save a few bucks by eliminating the oil drip hole from the upper crankcase half, that again drips oil directly onto the critical PTO end crankshaft bearing. With the oil pump left as installed by the manufacturer, the total oil consumption is 1 part oil to 40 parts gasoline. However, half of that oil is injected directly onto the two end crankshaft bearings, with the other half being injected into the air stream in the two carburetor venturi tubes.Just a recommendation after fighting the 550 engines. Remove the oil pump and mix your fuel at 40:1. They love oil.
If you are running ethanol fuel you will need to jet up as well.
The oil boils/air entrains at the pump from engine heat. The 550 Polaris fix doesn’t work well. Pre-mixing your fuel is the best answer.
Check those pilot jet, make sure they aren’t plugged.
No. The MAG side and the PTO side are right and left side references. The Exhaust side and Intake side are front and back side references. There obviously is a MAG side or PTO side piston, but that does not describe where on the piston that the ring failure occurred.
You can drill the hole out and machine a grove.The problem with removing the oil pump, is that the critical PTO end crankshaft bearing does not get oil directly injected onto it. Instead, it is blocked from receiving oil from the fuel stream, by the bearing that occurs next to it. In the Polaris model years after 2000, Polaris thought that they would save a few bucks by eliminating the oil drip hole from the upper crankcase half, that again drips oil directly onto the critical PTO end crankshaft bearing. With the oil pump left as installed by the manufacturer, the total oil consumption is 1 part oil to 40 parts gasoline. However, half of that oil is injected directly onto the two end crankshaft bearings, with the other half being injected into the air stream in the two carburetor venturi tubes.