Does breather trap all the oily deposits that get vented, or does it end up over the engine instead?

doesnt the breather exit the bottom of the bike somewhere normal though? or is it just a hole...

As standard, the crankcase breather vents into the airbox. Not really sure on the science of it..... (emissions?) Some people might not want oily crap going into the carbs, hence removing the pipe and fitting a self contained breather like the previous pic. I presume that anything nasty gets trapped in it just like the filter in the airbox only effectively in reverse, and that it needs cleaning once in a while. I seem to recall a mate of mine who has a 57 Chevy had issues with the way it was running and it was piddling oil out where it shouldn't have been. Turned out the breather were completely clogged and it was building excessive pressure in the cases....

ah right, yeah immitions it will be. is that whats the sub airfilter is for though no?

No, the sub air filter stops crap getting in the carbs around the slide and diaphragm. Or would, if it didn't turn to dust and fall out... lol

I think im right in thinking that race bikes or cars would use a catch tank with a breather to trap all the oil that tries to escape out of the breather.

Yes, if you look at some pics that were posted on here a while ago (maybe a in the for sale bit?) there were pics of an NC30 racebike with a whopping great cylinder in the tail and two large hoses which seemed to go back to the airbox and the crank breather. Cue me being wrong and it being something entirely different...

Porn, what mm is the connection point on the crank case breather may i ask? thanks.

RandomDan wrote:I think im right in thinking that race bikes or cars would use a catch tank with a breather to trap all the oil that tries to escape out of the breather.

Yep

thunderace wrote:

RandomDan wrote:I think im right in thinking that race bikes or cars would use a catch tank with a breather to trap all the oil that tries to escape out of the breather.

Yep

Endurance bikes that race for hours between pitstops often route it back into the sump via the dipstick hole, makes sense so that they don't run low on oil.