Author Topic: B31 breather  (Read 398 times)

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B31 breather
« on: 08 October, 2017, 19:34:24 »
 On a standard B31 is the breather necessary from the timing case cover ? Occasionally mine just pumps oil out. Most bikes from the same age (55/56) do not have the breather just a blank space. So I thought I could do away with my oil trail. Is it safe to do so ?    :-\   Griff
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Re: B31 breather
« Reply #1 on: 09 October, 2017, 09:44:44 »
If you decide to blank off the breather you need to arrange a suitable alternative breather or you will find the bike will leak oil all over the place, there being nowhere for crankcase pressure to go except though the joints or via the main bearing into the primary chaincase.

That breather was fitted from about 1948 right through to the end of production.

Before 1948 it was fitted near the drive side main bearing boss and the timing cover was a different part.

I would look for other causes of oil discharge.