Let's talk oil

So, I'm looking for a little help... There a few things I need and a few questions I need answered. I recently picked up an 85 jx700 and I can't seem to figure out where an oil leak is coming from. From what I can tell the oil is coming from the air box and the air filter is saturated with oil so it would make sense for the oil to be coming from there correct? Why is there oil in my air filter in the first place? Could it be caused by the petcock? FYI~ The petcock doesn't have an off position. where can I get a new petcock that will fit my bike and where is the best place to pick up tires? Any help you can offer would be aPprecated.

 

First Welcome to XJBikes! from the Boston mountains of NWA.

Sounds like an oh no from the po. How much oil are we talking about here, and is it only on the filter and not in the box? Some AM filters are designed to be oiled, OE was not.

Lots of oil and it's everywhere-it's probably coming from the crankcase breather tube which recirculates combustion gas back to the airbox. Which means either you have way too much oil in your engine or there is something diluting your oil (gas) and making it more volatile or both. I'm voting both. These bikes have a vacuum operated Petcock, so set to "Res" or "On" fuel only flows when the engine is running. Prime will flow until float valves stop it-it's best not to leave it set to "Prime" because too high float levels could flood your engine with fuel.

Don't ride it till you get this solved. I would start by changing your oil out for fresh motorcycle oil. These bikes don't hold a lot and the po may have overfilled. Your capacity should be marked on the case where the oil cap is. Anybody else know the capacity of this bike? (guessing around 2.5qts for a change). There's a sight glass on the side of the oil pan, correct level and you should have a small bubble visible at the top (on center stand, a least a few minutes after shutting it down)-you may need to clean the glass.

You need a manual. You have some work ahead to get this bike right & SAFE. You can find tires locally, but there are also good deals on-line (I got Dunlop 404's from Amazon), then you'll need to find a local shop that will mount them for you. Check the next few responses you get on here and follow the advice-we won't steer you wrong. Your XJ journey begins...

 

could mean a lot of blowby past the rings leading to over pressurization of the crankcase.

I would start with a compression test.

 

It's most likely not blowby; oil in the airbox is very common and usually comes from the two situations mentioned above.

If it's gas in the oil, it means BOTH a petcock problem AND a float issue.

The petcock is supposed to be "off" in both ON and RES if the motor isn't running, it's vacuum operated. PRI just turns it on.

The petcock should stop fuel flow when the motor isn't running; BUT the float valves should keep it from flooding into the crankcase regardless of what the petcock is up to.

Take your oil filler cap off, jam your nose in the hole and have a whiff. If it smells strongly of gasoline, then STOP running the motor and get on with fixing the problemS. If it just smells like warm oil, then you're probably just the victim of an overfill.

Which is also very common. MM is correct; somewhere in close proximity to your oil filler is a little number cast on the case. On the 550s it's "2200CM3" which means 2200 cubic centimeters-- the oil capacity.

Yours probably says "2500CM3" but you'll need to look. 2500CC=2.5 Liters.