My Harley-Davidson shoots oil out of the breather valve tube out the bottom end when I crank it after it has set for a couple weeks. I have one that does this and one that doesn't. Why does it do this?

Hi ladymac,

If it's an older bike where the oil tank is above the engine, like the horseshoe style under the seat etc... there's a ball check valve w/ a spring that prevents oil drainage from the tank and it's probably either "scored" or the spring is too weak to keep enough pressure on the valve. If the valve is leaking, the crankcase fills w/ oil and when you start it it's pushed out the breather. I don't know too much about the new ones but I'm sure they have a similar set up.

Hope this helps

Avery

I forgot to mention the ball check valve is in the oil pump... sorry

Avery

Avery92050 answered brilliantly. Softail models have the horseshoe oil tanks and gravity almost always wins with the check valve in the oil pump. Not much you can do other than change the spring and ball in the oil pump check valve or ensure you start the bike and give it a good spin around the block every couple of weeks. Good luck.