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NEW reed valve breather fits all Commandos?

Classic Norton Commando Motorcycles.

Re: NEW reed valve breather fits all Commandos?

Postby xbacksideslider » Thu Apr 20, 2017 12:26 pm

That's a beautiful piece of engineering, especially since it can be used on multiple models.
John Laing
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Re: NEW reed valve breather fits all Commandos?

Postby jseng1 » Thu Apr 20, 2017 12:39 pm

pantah_good wrote:Thanks Jim, it is a handsome part. The photo of the Combat / Maney version, is that shown mounted on a Maney case?


Yes. Its a Maney case.

Here's a vid of the blowby diff between a reed and no reed.

phpBB [video]
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Re: NEW reed valve breather fits all Commandos?

Postby texasSlick » Thu Apr 20, 2017 2:42 pm

jseng1 wrote:Slick - I started out with the timed Atlas breather. I got rid of it and use the reed valve. The timed breather does not work the same for all RPM when under load but the reed does. The air has to pulsate and it compresses. When the RPM changes - those pulsations do not always match the timed opening of the disc. We learned this in racing and discarded the timed discs. The reed doesn't care about timing - it just senses the pulsation. The four 1/8" holes in the cam are enough because once the positive air is pumped out there isn't much pulsating air movement going on. There are others who have tested and compared the reed to the timed breather - maybe they could chime in here.



Jim:

I can accept your explanation of the phase difference between the timed disc and the actual pressure pulse.

The point I was trying to make in my previous post, is with the timed disc in place, the reed does not improve the negative pressure in the sump, according to my measurements. I can only defer to your experience with the timed disc removed.

It would be interesting if you can provide some pressure measurements with your new reed valve on your Atlas' timed port (you once posted your rotary disc is removed). If such data shows a substantial benefit, it is a pity a complete tear down is necessary to remove the rotary disc.

Slick
1963 Atlas (Original Owner)

The Second Law (of thermodynamics) rules.
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Re: NEW reed valve breather fits all Commandos?

Postby jseng1 » Thu Apr 20, 2017 4:06 pm

Xbacksidelsider

Thanks for the compliment. I put a lot of hours into the design to make it work.

Slick

I have not compared the diff between the reed valve with the timed disc and the reed valve without the timed disc. That's another test that needs to be done. There are some simple tests that anyone can duplicate.

Loosen the oil cap. Without the reed breather the cap will bounce well off the oil tank. With the reed breather it pretty much sits still. You can also see the amount of bubbles in the video above. Pressure tests will have to be very sensitive. Just immersing the hose into the oil changes everything. Never make this test with water because it can suck water into the motor when backing off the throttle without a reed valve.
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