How to fix a leaky crankcase breather... For free.

[JEC]

When I was doing my 24K service I thought I would try something to stop the oil misting around my crankcase breather. Rather than buy an expensive aftermarket breather I decided to test a theory.

I pulled the breather out and found it was loose around the base of the breather box, where the bottom hose is attached with a pinch clip. This is obviously where the oil was seeping through so I sealed it all around with black silicon, then put a ring of silicon on the breather opening itself to seal the bottom of the hose as well. 300 miles later and not a single fleck of oil has seeped out.

Simple, and free. No need for a replacement breather.

Jason Cormier
Moto Montreal Cycle

[bella]

Originally Posted by JEC

When I was doing my 24K service I thought I would try something to stop the oil misting around my crankcase breather. Rather than buy an expensive aftermarket breather I decided to test a theory.

I pulled the breather out and found it was loose around the base of the breather box, where the bottom hose is attached with a pinch clip. This is obviously where the oil was seeping through so I sealed it all around with black silicon, then put a ring of silicon on the breather opening itself to seal the bottom of the hose as well. 300 miles later and not a single fleck of oil has seeped out.

Simple, and free. No need for a replacement breather.

Jason Cormier
Moto Montreal Cycle

What is the correct way to remove the stock breather? Is there some kind of wrench available that will fit in the holes around the base of the breather?? I know I can use a punch and hammer it out, but I'd rather not damage it.

[DukeDesmo]

Originally Posted by bella

What is the correct way to remove the stock breather? Is there some kind of wrench available that will fit in the holes around the base of the breather?? I know I can use a punch and hammer it out, but I'd rather not damage it.

You can get a wrench to fit, actually the supplied one with my Nichols breather will fit (but I didn't see it until after I had already removed the old one) however mine did come off quite easily using the 'long screwdriver & hammer' technique although to be fair I wasn't concerned about not damaging it - it is awkward getting the wrench in there between frame etc.

[bella]

Originally Posted by DukeDesmo

You can get a wrench to fit, actually the supplied one with my Nichols breather will fit (but I didn't see it until after I had already removed the old one) however mine did come off quite easily using the 'long screwdriver & hammer' technique although to be fair I wasn't concerned about not damaging it - it is awkward getting the wrench in there between frame etc.

Duke, what size wrench are we talking about here. I thought the breather was completely round??

[j.davis]

holes are in the base.

[JEC]

Odds are you don't "need" a replacement breather. A breather is just a one-way valve (reed valve in this case) that lets the pressure out of the crankcase into the breather box. Oil will mist up inside the breather assembly, that's why it is designed with a collector box to redirect oil back down to trickle into the crankcase again. My little fix here does not require removing the breather, assuming it's screwed on tight.

The stocker reed valve seem to be a little too loose causing excessive oil misting. A leak in the breather assembly causes this to seep out around the rear cylinder. But if it ain't broke, no need to fix it. You can check by pulling off the breather box and then looking inside the breather with a flashlight. You'll see the reed valves there. If they aren't stuck open, broken or bent, then you really don't need a new breather, you just need to take the time to seal up the whole assembly with silicon. Changing the breather has no positive or negative consequence on performance if the original was not broken - it's a bling item. In my case it was only leaking around the joint between the top of the breather and the rubber hose that goes up to the breather box. 6000 miles since I "fixed" it and nary a drop gets out, compared to before when it would pool oil around the rear cylinder within a few hundred miles.

Also don't do any wheelies. This sprays oil up through the breather where it either spits into your airbox causing smoke when the oil gets sucked down the intake, or it mists and leaks around the breather to the point of getting oil on the rear wheel (bad in any situation, worse when you are balancing on it alone).

[KneeDrag08]

Q: why have the breather routed back to the airbox? Is vac needed? Could you run a line to a catch can instead? I dont like the idea a dirty, oil contaminated air entering my airbox.

[Teufel]

Dont do wheelies????
Are you crazy??