Modern Vespa

I just got my 2006 LX150 back in may, second hand from a guy who took very good care of it. It only had 364 miles on the Odometer, so was like brand new. After about 2 or 3 months I notices some really black oily residue dripping down my transmition case. So I asked a few cycle riders and they all said "engine blow back" So I cleaned it all off, opened up the air breather, and cleaned out the foam filter and even took off the rest air breather and washed both parts down with de-greaser. Treated the filter with oil and re-assembled and everything was fine. Then last week it started again?? Is this just a natural cycle of the engine running? After so much time the air filter gets full of this engine blow back oil and starts running out? Here are some pics of what it looks like, and I can tell just where the oil is coming from... I just wanted to be sure it isn't much to worry about, aka not some sign of a problem...
I keep the oil topped off but have only had to do it once about a month after I got the scoot. The oil on the dipstick is very clean so I know the black burned oil is not coming from the oil pan.

I ride nearly every day to and from work, around a 30 mile round trip. So I have racked up almost 3k on her as the Odometer says 3187.04.

Greasy ?? Eric ??

I'll take a stab at this, but take what I say with a grain of salt. I've never worked on or even seen an lx150 outside of a dealer, so be forewarned.

I'd say that that kind of blow-by is not typical on a new engine. Normally you'd see something like this when the rings are kind of shot. If your crankcase isn't overfilled and your oil is clean the first thing I'd look at is the crankcase breather. On a car there is a PCV (positive crankcase ventilation ) valve in a breather tube that vents the crankcase gases back to the carb.
I'd wonder if the breather tube or valve(if there is one) is somehow messed up. As the piston moves up and down it displaces air in the crankcase, hence the need for that tube. If there is a valve it could be stuck closed, forcing the air back past the rings, into the air cleaner. I have no idea of a specific location to search though.

Hopefully somebody with more Vespa experience will chime up now and give you a hand. If not, at least you have a starting point.

Good luck

A similar thing happend after my first dealer oil change. It lasted a few weeks (I'd wash it and it would come back over and over) but it stopped and I haven't had a problem since.

When I over-filled the gas tank on my Fly, the evap system flooded with gas. Each time I would park in the sun, the pressure in the tank would force the gas through the evap-system, through the carb and out the air-box.

Does the problem show up more on hot days and after a long ride? Is your bike hard to start on hot days? Does the oil smell a bit like gas?

If it does, you probably have the same problem I did with the evap-cannister.

+1

I can say that I have not seen one do that. Seems like some pressure or something forcing that out.

I think a good thing to do here in the mean time is to get everything cleaned up so you can see exactly what type of fluid you're dealing with and where it's coming from.

I see that your "bubble" is completely full. Take your air box apart, remove and clean the filter, re-oil the filter, clean out the bubble, and clean the inside of the air box, then reassemble.

The port which you arrowed to in your photo ("Leaks from around this plug") is where the engine breathes in. As such, it takes in all sorts of dirt, dust, and crud that is then getting caught by the excess oil inside the airbox. From there, it leaks out onto your transmission case leaving this lovely mess you have.

I can see how what Born2BWild said might just be what is going on. As it has only happened twice, once during the hottest time of year here in Sacramento, and again recently. So temp isn't a consistant part of it. I am thinking it is just a matter of too much gas, as I usually wait for the fuel lite to come on then next day I put $6 even in it. Even though it could take more. I was messing with trying to fill the take up as much as I could back in July, so that might have been when that one happened. 2 or 3 weeks ago I was going to be riding alot, so stopped early to fill up and tried to put $6 in it and it stopped at $5.20 so tried to get a little more in. So will clean her up again, re-oil the filter and not ever fill it up all the way again...
Thanks everyone for the help and suggestions, will let you all know if it happens again and will pay closest attention to how much fuel I had put in her before...

Check out this post, it probably explains what's happening in your case.
ET/GT/LX: Hard Starting, Rough Idle, or Stalling Regards
Harvey