[yellow_cad]

I have a 72 OSSA MAR 2 stroke and since I am new to 2 strokes, I just wondered how the bottom end is lubed. Does the oil mixed with gas lube the bottom end or does it share the oil with the gearbox for that purpose?

 

[hogster]

with the mix delivered via the ports

 

[Hoofhearted]

The oil/gas mix is drawn into the crankcase by the vacumm created as the piston rises on compression. As the piston descends the intake ports open and the mix is pushed into the cylinder. The cycle repeats and you go forward.

 

[Chris41x]

If the engine uses premix (gas/oil) the oil is delivered to the bottom end and cylinder walls throught the air/fuel mixture. However, on some two strokes such as the Rotax motors in early Can Am's the oil is injected to the bearings and works as a constant loss system with the oil mixing in the crankcase with the air/fuel mixute and being burnt. I'm not sure about two stroke injection motors from Japan.

 

[deluxe72]

There are videos on YouTube that show how it works. Pretty neat.