90 softail oil leaking on bottom of rear cylinder

After reading your description, two ideas come to mind. If you have bench tested your master cylinder and it does not leak down. You have checked all fittings, lines, and master cylinder for leaks, and there are none. Then would suspect an issue with the rear brake caliper. You mentioned that you replaced the rear rotor due to it warping. I am curious to know why it warped? Raise the rear wheel off of the ground and spin the wheel. It should spin freely. Then apply and release the brake, to that wheel (a few times). After releasing the brakes, spin the wheel again. Does the wheel still spin freely? If it doesn't then I would check the brake pedal (see if it is releasing freely or binding), check the brake lines (see if there are and defects, flat spots, or kinks), and check the rear brake caliper (do all the cylinders retract with little resistance?) If the wheel does spin freely then I would check to see if you are using the correct type of brake fluid. Most bikes will require you to use DOT 4 or 5 brake fluid. If you substitute for a cheaper grade, it will affect the braking system. It may sound silly but I would double check that you are not accidentally resting you foot on the brake pedal. If that was happening, it would cause the brakes to fade. I hope that helps but If you have other details or question, let me know.

O/k I will assume it is a EVO (1995) not a Twin Cam (2005). If the leak is at the crankcase lower rear (below barrell) it is more than likely the crankcase itself is leaking. Will need a teardown to repair. It could also be the rear cylinder base gasket leaking. Oil will flow down the back of the crankcase when running.

You can ride it, but the leaking oil could cause problems if it gets on the rear tire, brakes, etc. You may as well replace both base gaskets at the same time.

The o-ring on the filter housing could be the problem, or maybe it was not tightened properly. You will need to clean all the residual oil off, position you bike in the upright position and determine the leak source. Hopefully it's not a case cover. Good luck, i hope this helps.

no it cant it has to be replaced.

No expert on newer Hogs but try this.If tank is replica of wrap-around type look on flat right-rear bottom over rear pipe.Just a flat bolt-head.Yep,it's messy,cover the pipe.Like I said,no expert. Follow bottom most oil line from oil pump back to oil tank. Maybe it "t's" off under frame into line that drops down toward ground. You could get a catch pan under there.I vote for the nut on tank.Wrap around,you know, the battery is in it.

It is most likely a leaky cylinder head cover gasket. There are also rubber seals that go around the bolts that hold the cover onto the head. Look closely and you will, very likely, see oil coming from one of these areas.

Blue smoke is probably oil smoke, as you figured. Now, how long did you run the bike once you got it fired up? Did you ride it? I'm wondering only because if you just fired it up, seen the smoke and didn't ride the bike, the oil smoke could have just been oil build-up in the cylinders from sitting and could clear up with a few miles. If you did ride it and the smoke persists, then you probably have worn rings/scored cylinders/leaking valve stem seals. That can be overlooked if it is not too bad, and you keep an eye on your oil level, like you're thinking. If your using a liter oil oil every 100 miles or something, then you might want to consider a rebuild if you plan on keeping the bike and sinking a bunch of money into it. It all depends on the severity and your personal comfort level with the situation.

is it even anything to worry about?Blue smoke is probably oil smoke as you figured. Now how long did you run the bike once you got it fired up? Did you ride it? I'm wondering only because if you just fired it up, seen the smoke and didn't ride the bike, the oil smoke could have just been oil build-up in the cylinders from sitting and could clear up with a few miles. If you did ride it and the smoke persists, then you probably have worn rings/scored cylinders/leaking valve stem seals. That can be overlooked if it is not too bad, and you keep an eye on your oil level, like you're thinking. If your using a liter oil every 100 miles or something, then you might want to consider a rebuild if you plan on keeping the bike and sinking a bunch of money into it. It all depends on the severity and your personal comfort level with the situation.,,,