I own a well maintained 98 Fat Boy with 30,000 miles and after a 75 mile highway ride the other day I noticed a lot of oil spray on my oil tank, air cleaner cover, cam cover and pipes. This has happened before but with only a little spray on my oil tank. First thought is I over filled the oil tank because I changed the oil a couple of weeks ago but I had ridden after that without this happening. With a bike this old it could be umbrella valves, or could it be a problem with the oil pump? I did notice one thing the other day, the bike had sat a couple of days after this happened and I checked the oil level which was way up, this is unusual for this bike because usually after it cools the oil level drops, any ideas?

 

When this happened to me back in '12, it turned out to be the umbrella valves. The rubber umbrellas were hard as a rock. I replaced them with the latest revision from the MoCo, which were a green rubber instead of the black rubber the originals were made from. No oil carryover since.


Before you tear into the rocker boxes, make sure your oil level is correct, though. You might also do a compression check, as a broken ring will allow excess pressure to build in the crankcase.

 

Something similar happened to me a couple of months ago. I had excessive oil in the filter housing and I had to run on half choke to get the engine up to speed. It turned out I had a dirty air filter and the motor was starving for air so it pulled oil from the pcv system. I don't know if that term is correct however after I changed the filter she ran like a champ again.

 

I'd check the umbrella valves and the check ball at the oil pump.

 

That's what I'd check, and keep the oil level at about 75%, before getting into the umbrella valves.

 

If the oil was changed after sitting, it's possible that you have too much oil in the motor.. Softails with the oil tank mounted above the motor, can allow oil to drain into the motor.. Yours, being an EVO, has a check ball in the oil pump to keep oil from dribbling into the motor. Sometimes that checkball seat picks up some material and doesn't stop the flow of oil from the tank to the motor when the bike sits. If you change the oil, you only drain oil out of the tank. When you fill the tank to the proper level and the run the bike, the oil pump pumps the excess oil in the motor back to the tank and the oiling system is over filled.

Check oil in the tank to see if it's overfilled then make sure oil is returning to the tank. Also the motor can return issues if a TC oil filter is used (so I hear). If OK, Umbrellas are something to look at. You might also want to run a compression / leak test to ensure that the rings are sealing well.. If not they can cause oil to blow out the breathers.

 

Thanks to all for the input, I rode it today for about 30 miles and no oil, I seem to notice it happening after longer rides at speeds between 70 and 80. With a 18 year old bike I am thinking the umbrella valves are probably hard so it would be a good idea to change them with the rockerbox seals. I did use a Harley oil filter for this change, they may have given me a TC one, they have before so I will check that. I don't have a compression tester but I am not blowing any smoke, the bike is running great and not making any noise. I guess I will try all recommendations one at a time and see what happens.

 

Well running at 80 for any length of time and all HD pretty much bleed a little.. For the age, the umbrellas could use replace.. you can drill out the oil return hole near the umbrella valve to something like 5/64.. TCs they drill them to 1/8.. Not sure I'd go that far tho..

You can still have very little oil burning but not have good ring seal.. But your issue sounds mild.