I have searched about this and read many posts about it. But still haven't came to a conclusion on my problem.

I have a 98 sportster 883. I bought it last month. I rode it just a couple miles a day and had no issues. On my first long ride (20 miles) at my destination I saw oil all over the back of the bike and back tire. I have been able to determine that it's coming from the breather hose under the seat. It only happens once the bike gets warm and I ride for more than 10 miles or so. It spots a lot out. Maybe 4-6 ounces in a 10 mile ride.
Once it starts spraying out if I pull my seat off and look at the breather tube I can see some smoky looking air spitting out with oil droplets and it really accumulates fast.

I have read several different opinions on what it could be ranging from oil pump check valve to engine crankshaft main oil seal. I've even seen people say a bad oil filter could cause it, but I don't understand how a oil filter that filters motor oil would have an effect on the primary and the transmission fluid?

I don't know much about these bikes and could really use someone's expertise here.


Thanks!

 

And yes, I have the tube routed straight up between the battery and oil tank which leave no low spots, tune goes from the tranny straight up.

And the oil levels in the main oil tank and the tranny are both at the minimum level.

 

If there is a breather tube under the seat, it should be the vent hose from the transmission. Your transmission vent hose just vents to atmosphere. Mine spits a little, but hardly more than a small misty spot on my swingarm. I don't see how it can push that much oil up the vent hose, there's no pressure inside the transmission to cause that. Your transmission only holds one quart of oil! You say that the transmission oil level is normal?

Are you sure the breather hose to the oil tank is attached? It goes from the camcase to your oil tank. Is your tank cracked possibly?

Always check your engine oil when engine is fully up to temperature. Do not add oil to the tank when engine is cold.

Interesting symptoms.

John

 

4-6 ounces in a 10 mile ride doesn't sound like normal venting to me. Unless you are significantly overfilled, there is likely another issue. That would be a quart in 53 - 80 miles!

 

I know you have a 98 and I have a 2000 but I am fairly certain they are alike. Here is a service bulletin from Harley about this little problem.
Sportster service bulletin.pdf