2pg engine rebuild

[EZGOfixer]

My neighbor and I recently performed a top end rebuild of the 2pg engine and it runs great. He said we need to take it apart again in order to add oil to the crankcase or it will sieze. I have not read that anywhere and am skeptical. Please advise.

[Dave Box]

Be skeptical be very skeptical. Of course you do realize that the crankcase receives its lubrication from the oil that you mix with the gasoline (unless you are still using the oil pump system). If you are premixing then the first tank after a rebuild is 40:1 and after that 128:1 which is 1 ounce of oil to 1 gallon of fuel. You should also be aware that you should add the oil to the fuel in a separate contain and agitate to thoroughly mix the solution before you add it to the fuel tank.

Dave

[EZGOfixer]

Thank you. That is what I thought. Good info- oil ratio for first tank.

[EZGOfixer]

Dave,
Just to confirm on the oil in the crankshaft. I can't answer my neighbor as to how the oil gets behind the piston to the crankshaft. Is there a port in the block that allows this on the 2 cycle?

Andy

[Dave Box]

As the piston goes up on the compression stroke it sucks fuel through the carburetor and past a one way valve on the crankcase into the crankcase itself. Then the plug fires and drives the piston down. The gasses reach the exhaust port on the cylinder and are expelled. At the same time the downward travel pressurises the fuel / oil in the crankcase and then the piston uncovers the inlet port so fuel is injected into the cylinder and around we go again. The big deal is that in a 4 stroke the fuel goes from the carburetor to the cylinder but in your 2 stroke it goes from the carburetor to the crankcase then the cylinder, lubricating the bottom end on its way.

Here are a couple of pertinent points that relate to the 2 stroke.

1. The exhaust and inlet are for a while both open and thus a 2 stroke is quite the little polluter. This is why the EPA have killed it for auto transport and why California have such stringent rules.

2. If the crankcase seals start to wear (as they will) pressure cannot be built up to tranfer the fuel and although you may have perfect compression and a spark the engine will not run. Sadly there is no real way to test the seals other than replacement.

Here is a gif that explaines the cycle much better than my words

http://en.wikipedia.org/wiki/File:Ar...e_Zweitakt.gif

Does that answer your question?

Dave

[EZGOfixer]

That explains it! Thank you again.