Modern Vespa

Hello Guys,

I do not wish to be bike specific because many bike using the same engine. My one is a 2014 model. I just want to find some opinion regarding my issues and a little explanation of this air box to be able to figure out the right modification approach.

The problem

A few weeks ago my bike started to spill oil on the floor after every ride via the air box. So I decided to remove and check it over. What I found it really worried me and I hope someone much more knowledgeable would be able to give me some idea.

So the air box was full of oil and junk, however the crank case pipe was not look as bad actually it did not had an oil init. the engine oil was little above the minimum. Last week I changed the reed valve, but have not tested the bike since because I still have not decided the Air Box mod yet and I also waiting for a water pump seal.


The Air Box Mod

I saw many different approaches, but cannot decide the best one to be hones and before I know all the functions of the original box I cannot decide.

It seems the safest mod is this one Airbox modifications

The crank case pipe and the water pipe stays in place, but it might lacking the nice sound and the performance increase of the K&N mods like this one

K&N Filter for MP3 500 -- Another Approach but LJClark put a flange that 10 or even 20 times larger than an original crank case breather hole. So it worries me the the larger hole gives larger sucking power and it might sucks up even more oil from the crank case.

The other problem I have is I cannot see any water run off pipe installed. Is it even necessary? what is the function of that water pipe on the original air box?

Other approach would be mine. I think reverting the crank case gases back to any engine is a mistake and can kill the engine eventually.

So my approach would be completely separate the crank case breather and fit an oil catch can on my bike and fitting a suitable K&N filter, however for the water run off pipe I still have not got a solution.

Any advice and input would be much appreciated. Here are some pictures of my air box

1. Wash and clean everything properly.
2.Install a new air filter (It seems to me that your filter is sick).
3. Continue driving and observe.
il entering the filter box is possible due to a faulty filter or a faulty piston group.

Step 1,2 and 3 done and still lots of oil in the box.

What is the faulty piston group means?

Should not be any other sign of a faulty piston?

The bike runs and starts fine.

How can I check the piston without dismantling the whole engine?

Would a compression test help?

Cracked MP3 500 Piston -- The Pictures (Finally)

use the search on this forum

MP3 500 air filter filling with oil, any ideas why?

Is it just oil or oil and sand and mud?

I did used the search function and read many post including the ones you linked, but I cannot see how those post would answer my questions sorry.

Anyway, I replaced the reed valve and serviced the bike today also did the safe air box mod, so I will see how it will perform and wether if there any oil or not. And most importantly I will see where the oil come from

If not the reed valve the piston or ring would be the other option.

It look like oil and sand and mud, but it might look different after the service.

Where is this part "reed valve". Photo please.

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Unfortunately the replacement of the reed valve did not solved my issue. I still have little spillage after a 15 miles journey. The oil dose not run all over my engine and out of the air box as before. Instead I removed the plug from the water pipe that running from the air box so the oil can discharge from there.

Next will be a compression test.

Thanks. I figured out what valve it is. There should be no oil in the filter box. You need to look for the error.