Modern Vespa

Please don't tell me I don't need one - I've posted multiple times about the quantity of oil I get in my airbox and that I have a paper filter that goes black too quickly.

Has anyone ever fitted an oil catch can or any such thing?

There's no room where the breather hose goes from the rocker cover to the airbox

Maybe stuff the hose with steel wool and make the hose progressively get higher as it goes towards the airbox (and a dip at the end to the airbox would be needed) so I might get some drain back into the rocker cover. Would want some method of making sure that no small fragments of steel wool could get back down into the rocker cover. Paranoia is a good thing.

Have considered mounting a catch can to the rear of the left rear shock and have that vent to open air. There's a convenient place to bolt it to the top rear of the transmission case. Been looking for a small one.

One concern with a can is that really need a design that won't block airflow with it gets full.

I use this one in my HD Sportster, check the other options as kits with hoses, etc, maybe can help to decide or flow new ideas? What I like is that is small (1.5" diameter and 2.7" height, so is easy to put in think space.

https://www.dkcustomproducts.com/4-stage-black-catch-can-for-external-breather-system-ebs-harley-2666.htm

Adapt to a larger size hose to act as a can
Steel wool at the highest point where you reduce back down before it goes back into the airbox
Make sure the oil can drain back into the valve cover not collect in a low spot
Lots of different ways to go with restrictions, including a pcv valve from a car

Yeah I've thought of the larger hose. Maybe maybe

Another possibility is to go old school. Back in the day (the 70's) instead of venting to the air box, the engine was vented to the atmosphere. My old Chevy had a small filter similar to a K&N style that pushed into the valve cover. Worked great!

I've though of a mini pod on the end of a hose that I could mount at the rear. no where else is a good idea in the gts as I don't need messy oil vapour in the engine bay etc.

but I known that based on my riding it would get very oily too quick and get smothered in a thick layer of gravel road dust become a solid lump of crap. and/or dribble plenty when parked on my front porch (which my scoot lives).

not anti the general idea, just don't see it working for me.

also see [NSR] What's Pissing you off Today? III (Post 2722794)

You make a great point. Good luck!

Had a thought on this the other day ...

I wonder if it's the air intake sucking from the breather under high revs rather than the engine pushing through the breather.

Does a PCV valve help this?

If this is the case than either really need run the breather to open air (via a can and/or mini pod filter) OR increase the rate that air can get into the airbox from the outside so as to reduce the suck

I thought the same. Was wondering if the tiny hole in the airbox was doing some science stuff like Venturi or Bernoulli or some other big words. Maybe the return passage wasn't big enough for the oil to escape the airbox vacuum.

return passage?

If oil goes in up there, it has to go back somewhere. I don't know what it's called.

There is only one hose from the engine (rocker cover) to the airbox. No other hoses between the airbox and engine.

Once oil gets into the airbox it won't make it back to the rocker cover so instead collects in the airbox and some gets past the filter back into the pipe to the throttle body.

think I'll order one of these https://www.aliexpress.com/item/1005004590474238.html 10mm

Oil gets up to the valves and doesn't leave fast enough. Thus getting sucked out by the airbox. I saw the words crankcase pressure but it's Greek to me how that works

The engine must be vented. If it wasn't you'd blow out the seals and have driving issues. Case is pressurized during driving. So which way do you intend to orient the one way valve?

PS, every engine looses oil this way. It enters the airbox as oil mist and becomes fluid as the oil mist cools down. Some engine designs are just better at recirculating/cooling oil before it leaves the case - labyrinth oil separator inside the valve cover. GTS doesn't use anything sophisticated, just lets the oil mist blow out to the airbox and, fingers crossed, most 'should' enter back into the combustion chamber and burn. But we know that most just ends up sitting in the airbox.

In the standard direction.

You said nothing. You aren't really sure if the oil mist is sucked out of the head by the airbox, or pushed into the airbox by the engine pressure pulses. So which way is the standard direction?

A setup like this might help. Pressure pulse enters on the side, oily mix is separated. Pressure leaves out the top, residual oil drains to tube. Just pull the plug in the bottom occasionally and drain the residual oil.

I thought of the Elite because it's a pretty compact part.

Hmm, just musing that pcv valves are probably made for different size engines, ie different pressure vs flow rate. So not confident in selecting one

If you were to use a pcv valve the arrow (denoting direction of flow) would have to point to the airbox. Otherwise you'd block engine venting and the internal pressure would blow out the transmission side crank seal. Not sure what the gain would be, maybe on a big engine where engine pulses mess with intake pulses...

If you look inside that oil hose you can see crusted oil and sludge. A pcv valve would fail fairly quickly and clog venting.

Just go on Webike and find an oil catch can, lots to chose from.

https://japan.webike.net/products/22822885.html

Hmmm. Cute. I'd only found cheap large car ones or expensive bike ones. That's size is interesting ...

Half the thing with a catch can is mounting it and routing hoses. The only real place is near where the left shock attached to the trans case. The hose from the rocker cover would have to start by following the router of the existing hose and then go up and along the top of the airbox. A return from the can to airbox would also have to go over.

Damn cramped

I'm not familiar with your market, is there a charcoal can/evap system installed. If you don't, then that space between outside panel and inner frame is ideal. And if you do have the charcoal canister I'd get rid of it as it causes running problems anyway and install the oil can in that space.

On my car the pcv valve is inside the head and clogs all the time, necessitating a replacement of the valve cover (single piece) they clog all the time. Catch can is simplest way out. However, if you think you have abnormal oil loss, especially via the airbox, then a culprit is worn piston rings. But you are going MALOSSI route now so you might find a reduction in air box filling as the malossi rings are going to be new and no blow by will take place to push oil mist out of the engine.

no evap crap. But trying to stuff a can up there with two hoses the size of the breather constantly flexing and also swearing when trying to get at it for maintenance ... I feel not a great place. Mine is the first of the HPE engines which are famous for drinking lots and lots. Piaggio did change the rings after about 12 months. I have been also pondering if the malossi would improve this (still waiting on oem parts before the install).

I was just thinking this morning that the exit of the breather into the box is right next to the cardboard and will get a lot of suck (see third arrow). maybe should stick a short hose on this that dangles down into the bottom of the box.

related photos, wish MV would let me reorder. (only 15km so clean filter)

the breather goes into the triangular thing.

part 30 (see prev) blocks off the long tube beside the triangle.

The problem is on the rocker cover end, probably mist from the cam chain
The mist gets a straight shot out the hose to the airbox
If you can make that stream of air change directions a few times before the hose, more of the oil will get separated out.

Many pcv valves are wide open in one direction, restricted 80% or something in the other

I had an oil separator in my black Honda. While working as a machinist, I used a 4 inch long 1.5 inch diameter aluminum butt stock. I rerouted the crankcase breather to flow through it with a clear discharge tube. After I rebuilt the head, I no longer had the oil in the air box problem but I didn't remove it.
Working on home projects is the ONLY thing i miss about working in a shop for a living.