Just started my 1989 FXSTC and the hose from the bottom of the oil pump to the air filter puked lots of oil (1/4 cup)into the air filter, Did this last summer also after sitting for a few weeks. Any ideas?

 

Sometimes the EVO do that after a longer standstill.
I could be wrong but I think you Americans call it ”sumping” or ”wetsumping”

Oil from the oiltank leaks pass the ball/spring no return valve in the oilpump.

And at the first start that oil gets pushed out of the motor.

 

... this sums it up

 

Yeah, They All Do That, Ken. All the "bottom breathers," anyway. You just put a drain pan under them the first time you start them up after they have sat for a while. My bike even did it when new, 32.5 years ago, when I had to let it sit for five or six months while at sea. Now, if they do it after a couple weeks, well, you can fiddle with it then, but otherwise, you just live with it.

Also, that's a big reason we all route that breather hose down to the bottom of the bike.

 

Normal and I recommend you instal an external breather to avoid this mess.

 

Common? Yes... Normal, No..... Could just need to be cleaned and reseated or the seat needs to be reamed and a new check ball...
https://www.ebay.com/itm/Oil-Pump-Ch...-/153308979509

 

Seems like I put a small K&N filter down under my last shovel. I'll look to see if they're still available.

 

Its normal for them to puke out the extra oil. Not sure this is totally avoidable when a bike sits. It’s not normal to this occur when ran regularly.

How long since the bike last ran?

 

8 months since I last started it.

 

The first thing you need to do is reroute the hose connecting the fitting in the crankcase to your air filter to the atmosphere.
Make sure you put a cap on the fitting on the back of the air filter where the breather hose was connected so that you don't have unfiltered air flowing into your motor.
Don't worry about putting one of those silly filters on it as the only thing they accomplish is blocking your breather when they get dirty.

Get a new spring for your check ball before doing anything else as your spring might just be a bit weak.
It is 30 years old after all.

Even if you don't ride it anywhere fire up your bike at least every 2 weeks for about 5 minutes so that any extra oil that sumped (a very small amount in that time frame) will be pumped back into your oil tank.