Hello everyone!
New guy Dan from Phoenix with a 91 Fatboy 80 cu in Evo.
Heres my problem.. If the bike sets more than a couple of weeks it will puke out about 1/2 a quart of oil on start up out of the vent tube. I had a Harley mech tell me this is normal on older Evo engs but I call BS! This is not normal in my book. Anything I need to know or anyone else have this problem? First Harley so I don't know sh*t about them! Thanks for any help.

 

It is normal on the older Evo's. It can be reduced substantially by replacing the check ball in the oil pump.

 

Yep ...not quite an "they all do that" but close ... as "Pothole" says clean and/or replace the spring and check ball and you should be good to go ... Do a Google search

 

Nature of that oil system design, oil tanks above the pump and only a small spring and 3/8" ball hold it all back from getting into the crankcase. Spring gets weak or the seat in the pump body wears a hair and it seeps by some while sitting, shovels and earley evo's are notorious for it. Main reason harley went to under the trans oil tanks on later bikes to stop this. So yes it's common. As been said replace the spring and check back ball, they are cheap and you can lap the seat in pump body by using a stock evo pushrod, the ball ends are the same size.

 

Dam, I did not know that. LOL I made a lapping tool with a suction cup and wood dowel then used some valve lapping compound on the old ball to clean up the seat.

Learn something new every day.

 

.
If I ever get around to pulling all the pictures off my old defunct computer I'll post up another tech thread I made about this very subject.

 

this is from the S&S wed site ....

A micron rating is given to show the efficiency of the oil filter (one micron is a millionth of a meter).


This leads consumers to believe that the 10 micron filter must be better for their bike. Here is where it can get confusing; though the 10 micron filter may have a higher filtration rating it does not allow the oil to return to the tank as fast. With this in mind, the 10 micron filter was developed for use with the Twin Cam style engine, which has a different oiling system that allows oil to be forced through a more restrictive oil filter. The reason for the tighter filtration was explained by the manufacture as necessary to assure all of the smaller passages, in the Twin Cam style engine, would stay clear of debris. If you run the 10 micron filter with an evolution style engine it will not be able to return oil through the filter fast enough causing the oil to back up into the lower end robbing power and/or causing oil to puke out of the lower end.

 

I also leave mine about a 1/2 pint low when I change oil. If you add a full 3 quarts and what is left in the engine when you drain it, you have to much oil. I keep mine about a 1/4 of the way down on the dip stick when hot. I can leave it set for two months during the winter and it never pukes when I start it up. If I over fill it, it can.

 

Like I said I don't really know much about Harley engines.. Can I access the oil pump externally to get to this check ball? Yes I need to go find a manual, I know.
Thanks for the help though, I have a direction now.

 

Yes, here is a guide.

https://www.hdforums.com/forum/oil-a...ve-repair.html