Engine Breather

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bluestoesonnose
Posts: 280
Joined: Sun Nov 27, 2011 3:52 pm

Engine Breather

Post by bluestoesonnose »

Had the bike running without the timing plugs fitted as I've just fitted manual CCTs, I couldn't believe the amount of air being pushed out and pulled into the hole. Why don't these motors have crankcase breathers the size of fire hoses?
tony.mon
Posts: 16287
Joined: Wed Jul 25, 2007 10:46 pm
Location: Norf Kent

Re: Engine Breather

Post by tony.mon »

It's possible to connect a breather to the oil filler hole, but actually the air inside acts as a spring, not a pump, so as the pistons come down you lose a little energy compressing it, but get it back as they go up again.

It's a bit more complicated than that, as they don't go up and down together, but the principle still applies to a degree.
Another possibility is running lowered crankcase pressures, (a partial vacuum) which means that all of the seals need to be in really good condition, and hope that the half-moon rubber cam cover seals don't get sucked in, allowing lots of oil to be blown out.

I've disconnected the breathers that go into the airbox and routed them to a catch tank and breather outside the airbox, mainly, to be fair, because I wanted to increase the airbox volume.
It's not falling off, it's an upgrade opportunity.
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darkember
Posts: 2194
Joined: Wed Sep 08, 2010 10:48 pm
Location: South Wales Abergavenny

Re: Engine Breather

Post by darkember »

tony.mon wrote:It's possible to connect a breather to the oil filler hole, but actually the air inside acts as a spring, not a pump, so as the pistons come down you lose a little energy compressing it, but get it back as they go up again.

It's a bit more complicated than that, as they don't go up and down together, but the principle still applies to a degree.
Another possibility is running lowered crankcase pressures, (a partial vacuum) which means that all of the seals need to be in really good condition, and hope that the half-moon rubber cam cover seals don't get sucked in, allowing lots of oil to be blown out.

I've disconnected the breathers that go into the airbox and routed them to a catch tank and breather outside the airbox, mainly, to be fair, because I wanted to increase the airbox volume.
By this you mean the breather pipes off the rocker covers? Any photos of the catch tank & location?
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lloydie
Posts: 20928
Joined: Mon Jan 17, 2011 11:16 pm
Location: In the garage somewhere in Coventry

Re: Engine Breather

Post by lloydie »

I'm thinking about making a breather bottle with a oil drain to the front sprocket cover so that if any oil enters the bottle it will help lube the chain . As I haven't seen any oil in the breather pipes that I fitted for the gutted airbox I can't see it being a problem .
Any thoughts ?
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VTRDark
Posts: 20010
Joined: Sun Mar 18, 2012 9:24 pm

Re: Engine Breather

Post by VTRDark »

Why not just feed a tube down there and keep the bottle high and out the way.

(:-})
==============================Enter the Darkside
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