79 Kz650 oil leak (I promise I tried looking)

Hey guys! I have an old 79 kz650 that I bought last summer and have been riding for a bit now. I'm still a new rider and don't have a whole lot of experience, but the other day after finishing a ride I noticed a lot of oil seemed to have sprayed all over the back wheel and exhaust. I see it dripping from this spot here below the battery. Can anyone tell me what this is? Or why it would suddenly start leaking now?

Thank you in advance for my noob questions!

Is that an airbox drain nipple? If so, you may be getting oil into the airbox via the crankcase breather. One possible reason would be that the engine is over-filled with oil.

Also, there should be tubing on the airbox nipple & you could route it towards the right or left, away from the tire.

martin_csr raises a very good question. How do you determine how much oil you use to fill the crankcase? Ed

I feel like there was definitely a rubber tube there before I took my ride the other day. Perhaps it came loose and fell off? There's a few new tubes on the bike coming off of the carbs, and none of them are held on by a clamp or anything. Perhaps this was the same case.

I feel like this COULD be an airbox nipple, seeing as how when I rev the motor the oil sucks back up, theres some kind of vacuum action going on here, but alas, I am still new at diagnosing this kind of stuff, and with a bike this old, I assumed the worst. The previous owner had the oil changed and carbs rebuilt last summer just before I bought it, so I haven't actually had to drain the oil and change it.

Should I drain it and change it? In response to your question Ed, it takes 3.8 liters from empty to full, correct? So barring any kind of build up in the case, that shouldn't overfill it, right?

I pulled out the air filter and it looks like there is a little bit of oil in the bottom of the box. I've attached a picture for good measure, along with a picture of the bike as well!

I really appreciate you guys and taking the time to respond!

Oops, forgot to attach the actual picture of the bike!

Have you checked the oil level? Whoever changed it could have put too much in, or you could have a carburetor malfunction that is filling the crankcase with gasoline.

poobear62205 wrote: ...... In response to your question Ed, it takes 3.8 liters from empty to full, correct? So barring any kind of build up in the case, that shouldn't overfill it, right? ..............

That amount of oil may be correct, but that is not how one checks the oil level on a KZ650. Take a look at the right hand side of the engine near the bottom. There you will find a site glass in the side of the engine. With the engine on the centerstand the correct oil level is obtained when the oil is between the upper and lower marks next to that oil level window - preferably near the top mark. If the oil level is above the top mark it is too much. Ed

Any new developments here?

This photo is on a 550. I think the oil level window may look different on a 650, but basically in the same place. When the bike is vertical and level, there should be a little bubble of air at the top of the window.

The 550 looks the same as the 650 to me. In the pic below the bottom of the meniscus is just below the upper fill line.