Has anyone successfully disassembled an OS 50 SX? It obviously can be done, but I can't find the key. This particular engine is unique so I need some help from someone that has done the 50 SX specifically.
I am not a rookie at engine repair, but this one has me stunped. I can't get the connecting rod off the crank pin.
You might have to remove the cylinder jacket from the casing. This is what I had to do for my Rossi 45. You remove carb & head, heat engine to 275 degrees, use skewer stick or chop sticks in the ports and use the piston/crank to force the jacket out. Use gloves to handle engine while it is hot. The connecting rod then easily slips off the crank pin. Be careful not to damage the parts. Assemble in reverse order. Hope this helps. Good luck rcflyer605
A mate of mine pulled his 50SX apart the other week to replace the main bearing - like you said, he had to remove the sleeve to get the rod off the crank, although it didn't require heating to do so. I think he did use heat to try to get the bearing off, but ended up levering it off with a screwdriver. The sleeve is notched, so alignment is not a problem, and he didn't seem to have any problems getting the piston back in the liner when he put it back together again.
I was surprised the bearing failed though - he has another 50SX and it looks like it might have the same problem.
Thanks for the input.
I've had the engine down as far as I could. That includes removing the cylinder. I cannot get the wrist pin out of the piston as there is no hole in the crankcase to allow its removal. Therefore, the piston has to stay connected to the connecting rod. Even with the cylinder out and the connect rod moved as far aft as it will go in the piston and the piston up against the crankcase, the connecting rod is still only about half off the crank pin. You cannot move the crank to BDC as there is a groove cut into the crankcase where the bottom of the connecting rod travels for about 300 degrees of crank rotation. I even tried loading the crank using the prop nut and a sleeve against the crankcase to pull the crankshaft as far forward as possible.
I need someone who has actually disassembled the OS 50 SX specifically to show me the secret handshake.
I had a chat to my mate who pulled his apart the other week - he wasn't that experienced with dismantling engines - he said the only issue he had was that there was gunk around the gudgeon pin up inside the piston which made it hard to slide the con rod backwards. However, he was able to do it without too much trickery - from memory he thinks it was done with the piston at TDC.
The only tricky bit was getting it back together - the ring has a locating pin for alignment, but you can't see it when you're trying to re-insert the liner, so it's hard to tell if the ring has rotated out of position.
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