Lots of Oil in Air Box

I have a 1981 KZ550ltd. It has generally been a good bike, with a few minor oil leaks and gremlins. I had not taken it out yet this year on account of my first child (a girl!) being born. I drained the oil before starting the engine, there wasn't much there. The engine takes 3 liters of oil. I did not replace the oil filter and then added 3 liters. Obviously this was a mistake. I started the engine and ran it for about 1 minute. Oil started running out of the overflow tube that drains the air box. The oil came up over an inch on the air filter. I cleaned out the air filter with gas and set it in the sun, and I drained the remaining oil from the bike and started over. After replacing the air filter and wiping out the air box I replaced the old oil filter with a new one and added about 2 and 1/4 liters of oil. I then ran the engine. The air box immediately began filling up with oil again. :sick:

Thoughts? It seems as though there must be some sort of vacuum issue, but I am not sure where to start. Thanks to all in advance.

Update:

I drained all of the oil out of the engine, and left the oil filter/drain open as well as the fill cap, so everything was free to run out and there was no more oil dripping. At that point there was about 1/2 - 2/3 of a liter of oil in the air box. After I drained the air box and wiped it clean there was still oil seeping into the air box from the crankcase breather hose. It was coming in slowly, but there was no question. I would wipe it clean, watch it seep in, and then repeat. Any help is much appreciated.

possible air emission reed valves stuck , located in valve cover, some how pressurizing the bottom end...... :S just undo the hose that connects to the air box and see if that cures the problem...... :huh:

When you add oil, how are you checking the oil level? Ed

another possibility , your engine is way over filled with oil...... and it's being shot up the crankcase vent....... your bike does have an oil sight window located in the clutch cover.... use it to verify oil level :blush:

turboking wrote: another possibility , your engine is way over filled with oil...... and it's being shot up the crankcase vent....... your bike does have an oil sight window located in the clutch cover.... use it to verify oil level :blush:

And don't forget the bike should be upright when you check the oil and not on the kickstand.

Personally I stand on the left side of the bike so I can balance the weight against my legs, lean over the seat, and use an inspection mirror to view the porthole/sight glass. For me that's a lot easier than trying to crouch down next to the bike on the right side while balancing the weight of the bike with one hand.

Yes the oil sight window is a bit hard to see through, so that is why I just drained all of the oil before adding more. The bike has been on the center stand the whole time. I am sure that the first time it was overfilled because I added three liters (the max amount) without changing out the oil filter (which still had a bunch of oil inside). The second time I drained it completely and and added only about 2 & 1/4 liters of oil, but still had the same issue where the air box filled with oil. :S

I definitely would start by replacing the oil site glass. Otherwise you have no accurate way of checking you oil, and that's a problem even if the engine wasn't pumping oil into the airbox. The site glass and clutch cover gasket are both still "Active" parts, so getting them is easy. Total cost of both is about $20 at Partzilla, so even a local dealer shouldn't charge a boatload for them. After the site glass has been replaced you can more effectively troubleshoot the problem because you'll know for sure how much oil is in the engine. One question - why would you change the oil without changing the oil filter? The muck in the filter area is just going to contaminate your new oil, and filters are cheaper than oil (and a lot cheaper than an engine). Ed

I bought a Kawasaki VN750 once, seller said it only started, when you add quart of oil. That is exactly what he did every time. I couldn't find out oil level until I realised engine had about double-triple amount of oil in it!
The only problem the bike had, was leaking O-ring around spark plug.

650ed: Thanks for that information. I will definitely replace the site glass and clutch cover gasket, not being able to see the oil level is a major issue. The reason I didn't replace the oil filter is that I had replaced it when I changed the oil before putting the bike away last fall, and the manual says that while the oil needs to be changed every 3000 miles, the oil filter only needs to be replaced every 6000 miles. That said, I have a fresh oil filter in now.

I let the oil drain out again (at $5 a liter this is getting sort of expensive and becoming an environmental hazard) and left it to drain for about 2 hours on the center stand. So I can't imagine that there was much oil left in the crank case. I then added 2 liters. At this point I know it isn't going to go well, but I am trying to look to see where the oil is coming from. After moving the bike into the direct sun I still couldn't see into the site glass to check the oil level, but I started it anyway. After about 20 seconds there was oil coming out all over underneath. :sick: :sick: :sick:

The brutal thing is that there were three puddles of oil where it was dripping off the frame in separate places. Two puddles of very dirty oil and one puddle of clean oil. :blink: :blink: :blink:

At this point any advice on troubleshooting / issue identification would be much appreciated. I am not adverse to a major tear-down if necessary to find all of the problems. One reason I got this bike in the first place was that I wanted to learn about engines... So here we go. In other news, the clutch has always slipped at very high RPMs so perhaps now is the time to address that as well.

If the clutch was slipping this would be a good time to address it while the clutch cover is off. It's possible the clutch friction plates are still within tolerance and can be cleaned up and re-used. This could be the case if the wrong type oil has been used. Do you know if JASO-MA compliant oil has been used in the bike? Ed

No I don't know if the oil has been JASO-MA compliant. I have just been buying the motorcycle oil recommended at O'Riley's and I have no idea what the previous owner used. That would be great if I didn't need to actually replace the clutch plates.