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P.J.
P.J., Technician
Category: Motorcycle
Satisfied Customers: 750
Experience:  10 years as a mechanic and fabricator in a privately owned, local, custom bike shop.
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89 Heritage soft tail

Customer Question

Hi. I have an '89 Heritage soft tail with an S&S 380 carb the shoots oil out of a carb port when I try to start it. It looks like a blow by or vacuum port with a hose that goes to the crank case. Do you know why? I also have photos.

Submitted: 2 years ago.
Category: Motorcycle
Expert:  P.J. replied 2 years ago.

Hi, my name is ***** ***** I'll be working with you today.

I've never heard of a 380 model S&S carb but your problem is due to a common occurrence called sumping. In softails it is commonly caused when a bike sits for a while. It is due to gravity pulling oil down through the oil pump check valve and into the crankcase where it isn't supposed to build up. The excess build up is forced out of the crankcase vent which is often connected to the carburetor to be pulled into the engine and burned by the engine.

If it happens all the time or when the bike sits for a very short period of time then you may have an issue in the your oil pump scavenging side or lines causing the oil to return to the tank slower than it is pumped into the engine.

I hope this helps.

Thanks, P.J.