baz
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In a commando oil tank you can see what the scavenge is returning
And you can see what the breather returns
Comstock / NYC sump breather test
- Thread starter Fast Eddie
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And you can see what the breather returns
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Schwany said:
...
"How can you tell it is not the oil [pump] return returning the oil? Can you see the breather exit inside the oil tank? ...."
You can see it with a clear braided hose. I used a clear hose to check the very first experimental reed valve sump breather on my race bike back in 1985 and I could see the oil pumping up to the oil tank in jerks with each stroke (at low RPM). My idea was to help pump excess oil back into the oil tank to eliminate friction losses - and it worked (with a bit of development).
Ron Wood took a different approach - he installed two oil pumps with different pickup locations in his short stroke flat tracker.
...
"How can you tell it is not the oil [pump] return returning the oil? Can you see the breather exit inside the oil tank? ...."
You can see it with a clear braided hose. I used a clear hose to check the very first experimental reed valve sump breather on my race bike back in 1985 and I could see the oil pumping up to the oil tank in jerks with each stroke (at low RPM). My idea was to help pump excess oil back into the oil tank to eliminate friction losses - and it worked (with a bit of development).
Ron Wood took a different approach - he installed two oil pumps with different pickup locations in his short stroke flat tracker.
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Nice feature that those sump breathers let the crank case pressure push oil back to the tank when the sump is full. 
I guess that was the point of this thread. Dah! I limited my thoughts to the breather working great at reducing crank case pressure without blowing out seals.
I only have the pump oil return and a frothing cNw breather installed in the timing chest. Doesn't seem to slow the motor down any, and it has seen 7K RPM a few times. I use the cave man approach to wet sump, and only let it drain back overnight after a ride before shutting the door on the oil feed. I have mastered human nature and don't forget the valve is there though (anymore
). Not recommended for people with multiple motorcycles in their garage, or younger guys still partying all night long and getting up early the next day to race or ride. It would be real easy to forget the valve is there, and end up with yet another Norton rebuild project.
I guess that was the point of this thread. Dah! I limited my thoughts to the breather working great at reducing crank case pressure without blowing out seals.
I only have the pump oil return and a frothing cNw breather installed in the timing chest. Doesn't seem to slow the motor down any, and it has seen 7K RPM a few times. I use the cave man approach to wet sump, and only let it drain back overnight after a ride before shutting the door on the oil feed. I have mastered human nature and don't forget the valve is there though (anymore
). Not recommended for people with multiple motorcycles in their garage, or younger guys still partying all night long and getting up early the next day to race or ride. It would be real easy to forget the valve is there, and end up with yet another Norton rebuild project.
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Perhaps there's a case to mod the lube system to one bigger pressure pump and let the breather valve do all the scavenging? Speedway motors use crankcase pressure to circulate the lubrication. They're low pressure systems much the same as the return on our Nortons.
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Sp
Speedway motors are an interesting example. The old 2 valve Jawa/Eso 500s used a one way valve at the bottom of the case and just blew the used oil down onto the track. I'm not sure if any of the speedway motors use reed valves but the Honda 450 single uses a sump reed valve to help keep oil off the crankshaft. Some of the BMW boxers also upgraded from a one way check valve to a reed valve.Perhaps there's a case to mod the lube system to one bigger pressure pump and let the breather valve do all the scavenging? Speedway motors use crankcase pressure to circulate the lubrication. They're low pressure systems much the same as the return on our Nortons.
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Total loss motors are a bad thing these days. GM four valve laydown motors have a reed valve in the top of the wet sump that uses crankcase pressure to pump the oil around the engine. I believe the JAWA has a similar system, though I haven't had one of these apart. The GM motor is such a simple design it's brilliant.
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Been thinking, to replace the return pump a small valved in bleed might be required to ensure continual flow.
Saber
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Oil is inside a commando oil tank....sometimes.
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I found air in my tires once, and fuel in my fuel tank. Thanks for the help.
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