Breather out the filler cap - advantages?

[Shill]

Hi all,

I've seen a lot of builds with an engine breather+filter coming straight out the oil filler cap port. Wondered what's the advantage of this?
Does it let you fully remove and blank off the breather box on top of the engine? Can see how that would be good for clearance if so. Any other advantages?

Cheers
Shill

Edited August 13, 2020 by Shill
Clarity!

[SiBag]

You will still need the breather on the cam cover.

[Gixer1460]

Its done to increase the capacity of crankcase breathing not an 'instead of' generally when a big bore or turbo charging is added as both increase ring blow by, both of which increase crankcase compression. 

[wraith]

As above 

A lot of times it's just for show, some say it helps performance?  helps if your bores/rings getting worn/old and your getting blow pass, of course it won't stop that problem 

[dupersunc]

Deffinetly helps performance if you have tuned motor, big bore, hi comp, turbo etc.

Gains can be quite significant.

 

Edited August 13, 2020 by dupersunc

[Hoomietune]

On a N/A bike just run a little filter on the cam cover  breather cheap as chips 

[Shill]

Nice one, cheers guys!

Already got the little filter on the cam cover, just looking for the lowdown on the other placement I'd seen about. Looks like I'm good for now!

Q2: how much smoking is reasonable out the breather filter... I asked when I got it dyno'd and the guy commented "yeah, she's just breathing a bit heavy" and seemed like nothing to worry about, when it's up to temp and sat idling it's a steady plume of smoke out there. Is that always the case? Might take a vid at the weekend.

[wraith]

Seen some with worn rings do it, but also seen good motors doing it when on a hot day in slow traffic and the engine is getting hot. If you're worried about it do a compression test with out oil down the bores and if reading is low with small amount of oil in the low bore and retest 

I always run with a crank case breather, 

1. I like the look of them.  always had them pointing backwards but I will let you open that can of worms 

2. If the engine is breathing heavily it helps get rid of all the extra pressure and then you may not blow a seal or gasket 

Go to Torques and get the bits to make your own up will cost you about £30.  I didn't know this and payed well over the odds for one off fleybay 

[colinworth79]

My bandit (1340 turbo ) has a couple of pipes off the clutch cover and one off the cam cover box that then go to a catch tank under  the seat . There is a bit of smoke come out when the engine has been used hard and is hot . 

 

[jonny1bump]

On 8/13/2020 at 11:13 AM, Shill said:

Hi all,

I've seen a lot of builds with an engine breather+filter coming straight out the oil filler cap port. Wondered what's the advantage of this?
Does it let you fully remove and blank off the breather box on top of the engine? Can see how that would be good for clearance if so. Any other advantages?

Cheers
Shill

Yes they great for creating a big oilly mess.

If the cover is not extended out clutch acts like a lovely paddle wheel old skool water mill styley. Nice.

Yes they can help with big cc but not mounted there.