Anyone having problems with pistons melting?
I bought the FL400 with the 617 rotax conversion in it. Ran great, had only 2 hours on it when i bought it. noticed bubbles in the fuel line and found that a fuel filter was partially plugged. It was dying on me and bogging down. there were 2 fuel filters. removed the plugged one and it worked great after that. went riding after a couple hours it just died. Turns out it melted the piston in cylinder 2.
Repair time: replaced cylinder 2, piston 2 and the rave valve with parts from FARR-OFFROAD. Parts looked great. rebuilt the carbs and set them to be richer. No more bubbles in the fuel line. Checked compression. New cylinder 2 had 150psi, old cylinder 1 had 180psi. didn't know it was way too high. Ran great for at least another 2 hours or so. Kept checking the spark plugs and they were always black. fuel was mixed 40:1 with royal purple 2 stroke oil and gas was 91 octane. with only 2 hours or so on the new cylinder 2, the older cylinder 1 melted. damn. Pulled the head and noticed that my new cylinder 2 had scoring on the cylinder wall. on the back you can barely feel it with your finger nail. The front had scoring but couldn't be felt.
Any idea what is causing this? I assume the 180PSI cylinder 1 was extra hot because of the high pressure but don't know why it was so high. It looked great when I took the
Engine apart to replace cylinder 2. And why would my new cylinder 2 have scoring on it?
Just don't want to replace another cylinder and piston to have it die on me again.
any help would be greatly appreciated. Anyone else have issues like this? I am using the recommended spark plugs BR9ES. The first time i was using BR7ES plugs.
This is piston from Cylinder 2 (first one that failed)
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This is cylinder 2
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This is the piston from cylinder 1
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This is cylinder 1
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This is the new cylinder and piston (cylinder 2) that only has about 1 or 2 hours on it. It was the replacement for the melted piston of cylinder 2
Noticing the scoring. Has it on front and back of the cylinder.
(SEE POST NUMBER 2)
There are the spark plugs. they were black every time i checked them and the Engine temp never got above 187.
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Rotax valve from cylinder 1 had oil in it
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