I just bought a 99 dyna, drained the primary, and got 1-1/2 qts of oil out of it. I checked the crankcase oil, it's about 1" over hot full on the dip stick. If the previous owner overfilled (massively) the crankcase, can the oil transfer into the primary? I don't think you could put 1-1/2 qts into the primary through the derby cover.
Thanks,
Mike

 

The 2010 touring manual calls for 38 fl.oz. unless the Primary cover was removed and then it requires 45 fl.oz.

The crankcase oil and primary oil are seperated and do not mix together.

The manual also states , do not over fill primary fluid. It can cause problems finding neutral, rough clutch engagement, incomplete disengagement and clutch drag.
If you don't have a service manual for your year model consider getting one and follow the recommended levels.

If you just got the bike it wouldn't be a bad idea to drain the crank oil, primary, and trans and replenish, Then you know what fluids you have in the bike and at the correct levels.

 

+1 on ZZZCICI's post.

I'm not a factory certified Harley wrench but an indy mechanic told me once that a leaking seal can push fluid from crankcase (and I dont remember where it pushes it to). If you change all fluids and fill to spec, if one goes up and another goes down, you could at least roubleshoot it better. Be sure and keep us posted whether you find anything or not.

 

There is a seal that keeps the oil from migrating from the crankcase into the primary. I was putting in 38 ounces in my primary like the service manual called for and draining 54-60 ounces. The seal was just a few dollars and was repaired for me under warranty.

 

I suggest you refill to the correct levels and keep an eye on your engine oil. If that goes down noticably, check your primary. Obviously if that has gone up, you probably have the problem Sefferdog had.

I don't think it applies to your bike, but some earlier ones suffered from a loose drive-side bearing, which is not so easily put right. It is more likely you have either an over-enthusiastic previous owner, or a leaking seal. Neither should cause you any problems until you diagnose which!