crankcase breather

[dansofield550]

Been looking over the bike now that it's in daily use and notice the breather letting oil out, not much but noticeable,
How much of a puff of gas is there normally? I know it's a bit hard to put into words, but any pointers would be nice to put my mind at rest, I thought today after I was checking levels that I'd lost a lot of oil but think it may have been a blocked oil filter stopping oil returning to the tank, can this happen? I drained the oil and it only measured a little less than was put in 300 miles ago, cleaned the oil filter and refilled and have a nice flow agian but the breather is making me wonder now. Thanks dan

[Rob Harknett]

Oil will drain past the pump into the crank case when standing, so will take a while to return the excess back to the tank.
At this time expect a little more oil to dribble out the breather. You will get a dribble, not only air will breath out, more like oil mist.

[dansofield550]

I guess over filling would lead to oil being ejected from the breather, in the manual the breather is just a hole, I have a length of copper tube in mine, is this right or a mod from previous owner? My pipe has a slightly pinched end too .

[Rob Harknett]

Yes usually a piece of pipe approx. 3" long bent slightly backwards, not nipped up at the end, this can be seen in your bikes parts list.

[John Jarrett]

That sounds like the chaincase breather rather than the crankcase breather to me. Are we talking about the copper pipe at the back of the chaincase or the vent between the bearings which exits behind the chaincase itself?

[1608]

Chain case breather is unlikely to drip oil unless its too full for one reason or another. The engine breather will lose a little oil and its only because the oil mist from the crank case collects in the outlet pipe and then drips. It appears to be losing more oil than it actually is. All singles do this to a certain degree.

[clive]

Don't know the lightweights but on a heavy weight the crankcase breather will "smoke" if the engine has been overheated and the rings as a consequence are jammed in the piston. In normal operation it will pulse but should not smoke heavily. I imagine its the same for the G2.

[Tolly]

Don't worry about it. As Rob states, they all push out an oil mist. If I do a 25 mile run on my G5 and then park it on the drive I will get quite a few drips of oil staining the drive. Wifey is never pleased but that's normal.

[cbranni]

The 3" long copper pipe is the pipe that carries the wires from the alternator, the breather hole (or bolthead with a hole in the head depending on model year) is close by, with engine running you can feel a pulse of air every rev.
If the breather is blocked or not working, would the engine breath through the bearings into the primary case? the pressure would then vent through the pipe carrying the wires?
...........thoughts anyone

Colin

PS ...........yes they all drip a bit after a run

[dansofield550]

It's definitely the engine breather I'm looking at, its q bit longer than 3" though, mine is pointing downwards and can just be seen when you get on your knees sticking out from the gap between the gearbox and chaincase, today's drama was a new oil leak from the base gasket, quite a big one this then oiled the plug, luckily I had a spare plug, looks like I'll be checking head torque tomorrow, tje engine oil level had until then be steady.

Oh well Christmas break could be a top end rebuild