Timed breather gear

[PanPal]

Why do we need the timed breather gear? Does it just keep it from puking oil out while running or create needed back pressure at some point in the stroke of the motor? Not that mine is causing problems or anything, just curious why you couldn't remove it, make a plug with a hole for venting and possibly regulate flow. After many beers I got to thinking, most motors I have seen have no timed venting.

[fourthgear]

One thing is HDs are dry sump crank case and the pistons do create pressure coming down and I believe those two are why the breather is timed , but I'm sure some one will have a better expansion for ya.

[Cotten]

PP!

When the pistons come down, they pressurize the cases. This actually gives an important springy rebound effect, cushioning the rapid stop of the pistons at the bottom of their travel.
In order to scavenge the oil, the breather must not only open at the proper interval to push/suck it out, it also must relieve the vaccum when the pistons are rising.

To really appreciate the Harley breather, you aught to investigate the Indian vent.

...Cotten

[Panacea]

I saw a new type of breather that has three reed valves instead of a rotating window, could this be a simple solution for breather timing? Or are there other variables to consider besides vacuum and pressure?...MW

[Cotten]

Historically, HD's revolving breather was the solution.

That's why I pointed out Indian's primitive approach.

...Cotten