Crankcase Breathers.

[koko64]

It appears that the late model breather is sealed to the cases with an o-ring while the alloy types use an alloy crush washer. Are there any aftermarket breathers that use an o-ring between the breather and cases? I am fitting an STM type and it has no recess for an o-ring so I will use an OEM crush washer and sealant. Anyone seen any other ways they seal to the cases?

Of note is that the STM breather flows (exhales) substantially more air than the plastic oem breather, or should I say, has much less restriction. Blowing back the other way, both had similar restriction but for the oil drain back holes (maybe the oem a little more restriction). Don't know if that's of any consequence either way. I didn't 'test' an alloy oem breather.

[silas]

I installed a red Ducabike breather on my M900 200 miles ago.   I used permatex on both sides of the alum washer.  It hasn't spewed a bit yet.  I think it was $70 , so pricey.    Original plastic one w alum band spewed a lot.

[the_Journeyman]

I've got a $10 piece (looks like a tiny pod filter) from Advance Auto on mine.  Not a drop leaked.  Granted it's not been over or done much of a wheelie with that one, but so far it's worked fine.

JM