Engine breather?

[Bitza]

Hi all, Next subject the engine breather and in particular the catchment bottle, long story but I'm a bit short of room to locate the rear ignition coil and would like to locate it where the 1994 catchment bottle is. Well I've never had anything caught in the bottle and certainly have never looked at or emptied it, so does it really perform any function in reality or is it there to satisfy some legal type requirement? As it would suit my purpose far better to connect the engine breather direct to the air filter box and chuck the collection bottle in the hedge. Any thoughts or experiences to share? Thanks as always Bitza.

[Nickj]

It's a part of the emissions control and in theory allows oil droplets to condense out and drop back into the motor and vapour to pass into the air box and so be burnt as the engine runs.
On my last two 750's I removed it and replaced it with a little filter (one of the small cone types). You do need this to be positioned so that if the engine decides to start spitting out oil it doesn't end up on the back wheel.
I'll probably do the same on my S2R.

Removing this also fixes the oil emulsion problebd (the white mayonnaise) that you often get in damp weather as the catch box also allows water vapour to condense out and droop back into the motor.

[Flip]

Be careful what you get rid of there- personally relocation might be a better option than junking it all.

It is the fact the engine breathes recycled air which gives the motor it's tendency to emulsify the oil due to condensation forming inside the crankcase- there is a tube from the little catch tank going to the air box that is the cause of this.

I got rid of that tube some years ago to stop the oil turning to mayonnaise meaning that my engine no longer breathes in recycled air from the crankcase but only nice fresh stuff from the outside world. I kept the little catch tank but ran a short length of tube for it breathe away from everything.

Don't be tempted to get rid of the reed valve assembly itself on the rear of the crankcase though- it looks cool to have a mini K&N style filter there instead but you will be constantly plagued with an oil mist covering everything in that area and it's not great for the motor.

I know lots of people have done away with it without reporting any issues but don't just take my word for it:

http://www.ducati-upnorth.com/tech/breather.php

[utopia]

I also removed the tube connecting the catch tank to the airbox, but left the catch tank in place and fitted a small filter to its outlet.
I know that others have removed the tank altogether but for me, that was too much disruption to the std system and likely to cause issues.. after all, the tank wouldn't be there at all if it wasn't needed.
I guess you might argue that the tank merely seperates out any liquid oil before shooting the vapour into the airbox, but I still preferred to play safe and leave it in place
The tube connecting it to the airbox on the other hand, is just a minor addition for emission control purposes .. and its raison d'etre is more political than practical, in my opinion.

That doesn't help with your packaging problem though.
Have you considered changing to a lithium battery ?
This opens up a whole can of worms regarding their safety, but they do release quite a bit of battery box space as well as saving many kilos in a high location .. 5.5kg in the case of the old wet batteries.

Another option might be to fit a filter on a longish "stack" tube above the breather unit, in place of the tank.
This may partially substitute for the function of the catch tank.
I've heard of this being done but can offer no insight as to its effectiveness on a monster, I'm afraid.
I do run a similar system on my trailie thumper though, and haven't had any problems there (and being a big single, you might expect its need for decent breathing to be more critical). This is an older engine though, built in the 90s and with its design probably hailing originally from the 70s. It originally also had a catch/separator tank system, but no controlled "breather valve unit" as far as I'm aware (certainly not an external one anyway).

[Nickj]

On the old bevels and singles you were likely to see a tube clipped to the frame rails under the seat with the pipe coming from the engine breather. You only see the boxes and connections to the air boxes later ... post any generic and euro tests came in. At the end of the day it is just a PCV ventilation system to relieve any crankcase pressure that are caused by blow-by gasses and allow a bit of fresh air back into the cases. Unfortunately the little catch tank just allows the water component in and out, doesn't really reduce it just ensures most goes back in again; that is you have to work the engine hard and get it very hot to loose any significant volume of moisture once it's got into the cases.
Just a point of interest here, the mechanical valve just flaps around a bit too much (it's pressure a differential operation and the pressure differences to open it are very small) and isn't really very good at keeping the oil free of water and fuel contamination. Typically a smarter solenoid system using inputs from engine speed and TPS works better, at least 50% less moisture in the oil which is what you tend to find on current generation crank vent systems.