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Author: Subject: 2 stroke crankshaft vs 4 stroke crankshaft
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[*] posted on 14-5-2008 at 14:27
2 stroke crankshaft vs 4 stroke crankshaft


in a 2 stroke engine the crankshaft is two discs with holes drilled for the pin for the main piston rod pin and some sort of thingamabob to transmit power to the transmision. the crankshaft rests on beefy heavy duty bearings. in contrast the crankshaft for a four stroke engine requires complicated machining and it rests on tiny soft metal bearings about as thick as a stick of gum and about as big. it seems like it would be better to make a four stroke crankshaft more like a two stroke crankshaft.
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[*] posted on 15-5-2008 at 09:29


Some Suzuki and Honda 4 strokes use ball bearing cranks.

Plain bearings are much quieter and don't necessarily wear out sooner than ball bearings.
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[*] posted on 15-5-2008 at 12:29
piston rods for 2 stroke vs four stroke


another thing is the piston rods. in a four stroke the piston rods are two pieces which bolt together, because otherwise it would be impossible to get the piston on the crankshaft. in a two stroke the piston is one piece and the main piston rod bearing is some needle bearings in a plastic cage. removing the piston rod in a two stroke is a major hassle requiring a hydralic press of some force and precision. is there some reason why two stroke piston rods couldn't be two pieces bolted together with the needle bearing cage in two halves?
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[*] posted on 15-5-2008 at 14:26


I might've seen them both ways, I'm not sure. I'm not big engine fanatic.

It's probably cheaper. Two strokes are small and cheap as hell, think about it.

Tim




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