All Harley Davidson V Twins have a design flaw with small engine crankcases, can't control high pressures.?

Harley Davidson V Twins with small crankcases present some real challenges when it comes to controlling crankcase pressures. As the pistons rise and fall in their cylinders, the volume of the crankcase changes the same amount as the displacement of the engine.


Without some type of venting system the seals and the gaskets would fail immediately.


Bottom Line: its normal for all HD Engines to leak oil from the breather tube that attaches to the air box., then the oil leaks out and gets all over the engine and on your pants legs, its a mess!


Why don't HD just make a bigger crankcase and forget about the stupid oil tank?All Harley Davidson V Twins have a design flaw with small engine crankcases, can't control high pressures.?
I agree. As much as I like HD it's still a puzzle as to WHY so many people want to shell out so much cash for a 50 year old engine design that leaks, vibrates, too heavy, too slow, too thirsty. A Ducatti is the polar opposite -- no leaks, smooth as butter, trim %26amp; sleek, fast as hell and gets decent fuel mileage. I don't blame HD for building the bikes that they do -- they're simply filling supply %26amp; demand. Heck, they even tried to go high tech with the V-Rod but the public stayed away in droves. As long as there are middle age biker wannabes that like to dress up in leather chaps and salad bowl helmets there will always be a Harley Davidson.All Harley Davidson V Twins have a design flaw with small engine crankcases, can't control high pressures.?
Bart, you obviously do not know what you are talking about. HD does not have a design flaw that causes an automatic oil leak.





All internal combustion engines have venting for internal pressures.
Bottom line:


When oil leaks from the breather there is an internal problem, not a design flaw. Air and oil are supposed to be separated so that air comes out the breather and oil goes to the tank.





Breather = vent.
because you need oil in an IC engine
my don't leak any oil and it has over 80,000 miles on it