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NEW reed valve breather fits all Commandos?

Classic Norton Commando Motorcycles.

NEW reed valve breather fits all Commandos?

Postby jseng1 » Wed Apr 19, 2017 11:43 am

NEW PRODUCT RELEASE

This new reed valve breather fits all models of Commandos & Atlas without any machining necessary.
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The 750 Commando and Atlas version screws into the original breather vent on the left side case near the cam. Simply remove the breather vent and install the new one way reed breather. If (or whenever) your lower end is apart you can remove the original rotary valve and spring because you will no longer need it.
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The 850 Mk 2 version screws into the original vent at the rear of the timing chest. Just remove the old vent tube and install the new reed breather (see Mk3 elect start version at bottom).
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For those who have an electronic tac (or no tac) the front tac mount version fits all 750/850 Commandos. Bolts right on with no machining but you have the option of plugging the vents in the timing chest (plugs provided). 850 owners should plug the original vent at the rear of the timing chest.
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For Maney cases and Combat versions you replace the original vent at the rear case. You have the option of plugging the timing chest vents (plugs provided).
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This breather uses a high quality stainless steel reed valve from the BMW twin. The reed allows positive air pressure to escape on the down stroke and then shuts to prevent air from re-entering on the upstroke. This reduces crank pressure and helps prevent oil leaks.

Go here for more details:
http://www.jsmotorsport.com/technical_r ... eather.asp


EDITED
Here's an added photo of the new reed breather on a Mk3 electric start (edit - with aftermarket starter). Remove the original vent tube and install the new breather it its place.
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Last edited by jseng1 on Fri Jul 14, 2017 12:45 pm, edited 9 times in total.
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Re: New reed valve breather fits all Commandos

Postby L.A.B. » Wed Apr 19, 2017 12:11 pm

It doesn't look as if it will fit an 850 Mk3 with the starter motor in place.

jseng1 wrote:This new reed valve breather fits all models of Commandos & Atlas without any machining necessary.

The 850 version screws into the original vent at the rear of the timing chest. Just remove the old vent tube and install the new reed breather.
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Re: New reed valve breather fits all Commandos

Postby jseng1 » Wed Apr 19, 2017 12:21 pm

Thanks for bringing that up L.A.B. I forgot to post this photo of the new breather on an electric start Mk 3 (edit - with aftermarket starter). See below.

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Last edited by jseng1 on Fri Jul 14, 2017 12:46 pm, edited 2 times in total.
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Re: New reed valve breather fits all Commandos

Postby L.A.B. » Wed Apr 19, 2017 12:24 pm

jseng1 wrote:Thanks for bringing that up L.A.B. I forgot to post this photo of the new breather on an electric start Mk 3. See below.

Image


That's the 'dynodave' starter though, which is shorter than the standard Prestolite motor.
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Re: NEW reed valve breather fits all Commandos

Postby L.A.B. » Wed Apr 19, 2017 12:32 pm

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Re: NEW reed valve breather fits all Commandos

Postby jseng1 » Wed Apr 19, 2017 12:44 pm

L.A.B.

The tube that threads into the rear case is offset on the breather so you can rotate it for more clearance where you need it (the hose barb can be changed). And the Mk3 threaded case hole has more angle to give the breather more clearance than the Mk2. I don't own a Mk3 with a prestolite starter so I sent a sample out to a friend to check the fit and he took the photo of his bike with the Dyno dave starter (me not knowing the diff). If you or anyone else on this forum wants to work with me to make sure it fits the prestolite starter (at discount or refund) - please PM me.
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Re: NEW reed valve breather fits all Commandos?

Postby texasSlick » Wed Apr 19, 2017 2:39 pm

Jim:

In regard to fitting a reed valve to an Atlas with the timed breather, my measurements have shown no change of pressure in the sump when the reed valve is fitted in series with the timed rotating disc in place, as compared to the timed disc alone.

I modified an XS650 valve to screw into the timed port in the same way as your new valve. I replaced one of the rocker spindle cover bolts with a pressure tap to measure the pressure in the rocker box (not the sump, but good for a measurement of relative change) and found it to be negative 18 inches of water (2000 rpm & up). When I removed the XS valve and measured the pressure with only the timed disc, it was still negative 18 inches of water!

I have always believed the timed breather to be ineffective due to leak back past the rotary disc, but these results proved me wrong. I now suppose the timed breather ineffective because the porting inside the camshaft is too small. Removing the disc will not resolve that condition, nor will a better one way device improve the internal flow characteristics.

You new valve appears to be a fine piece of work and I am sure it will be effective in the right application. But, I have to pass on my experience and data, and I am skeptical that it will result in more negative pressure in the sump when applied to the timed port, even if the rotating disc is removed.

Should the cases be split, would it not be more effective to drill and tap a 1/2 - 20 port somewhere else in the cases and plug the timed port? With the magneto in place, I do not know where that somewhere else would be, but for coil ignition Atlas' one of the other sites you mention should work well.

As for me and my magneto, I think a sump plug breather is my only option.

I hope you do not feel me a nay-say-er. Good luck with your new product.

Slick
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Re: NEW reed valve breather fits all Commandos?

Postby pantah_good » Wed Apr 19, 2017 2:41 pm

Jim, could you explain why there is a 3/8" hose or a 1/2" hose for your Combat version please?
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Re: NEW reed valve breather fits all Commandos?

Postby jseng1 » Wed Apr 19, 2017 3:01 pm

pantah_good wrote:Jim, could you explain why there is a 3/8" hose or a 1/2" hose for your Combat version please?


In case someone puts the Combat location sump mounted reed breather on their 850 elect start - because the Mk3 has a 1/2" hose fitting at the oil tank. I'll edit the web page to make it more clear.
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Re: NEW reed valve breather fits all Commandos?

Postby pantah_good » Wed Apr 19, 2017 3:51 pm

Then I'll assume one hose size doesn't work any better than the other. My other question, which I really hesitate to ask for fear of sounding smart aleck or especially ignorant, but is there an operational advantage for using your reed valve over one like Mike's XS 650 reed valve? I'm getting close to final assembly of my engine once I button up my gearbox and I haven't settled on a breather valve yet, and there is a significant price difference there.
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Re: NEW reed valve breather fits all Commandos?

Postby The Buckeye Rider » Wed Apr 19, 2017 5:14 pm

Sorry boys and girls but for $195 I'll have to stick with my Motor Mite vacuum valve @ $5.95 I just really don't have that kind of excess cash around.
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Re: NEW reed valve breather fits all Commandos?

Postby JimNH » Thu Apr 20, 2017 4:11 am

I don't have any oil leakage issues. Is there any other advantage to install one on a MKIII? Thanks

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Re: NEW reed valve breather fits all Commandos?

Postby JimC » Thu Apr 20, 2017 6:26 am

The Buckeye Rider wrote:Sorry boys and girls but for $195 I'll have to stick with my Motor Mite vacuum valve @ $5.95 I just really don't have that kind of excess cash around.
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Tried one of those years ago. Found it provided a placebo effect, but little else. Oil still passing crankshaft seal, tach drive still weeping. Went to an XS reed valve. No more leaking and weeping. Don't recall exactly how much the XS valve cost, less than $20 IIRC.
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Re: NEW reed valve breather fits all Commandos?

Postby jseng1 » Thu Apr 20, 2017 11:17 am

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. I use the reed on at the cam vent without the timed disc. There are others who have tested and compared the reed to the timed breather - maybe they could chime in here.

Panta - The XS breather is a good one and I've used it. The problem is that it doesn't mount directly to the motor to pick up heat and in the winter the oil can get water in it and turn gummy in the reed valve. Its best to have the valve mounted directly to the motor so it stays warm and doesn't plug up. I also didn't like the way the XS breather looked - its bulky and I had to modify the tubes to work with the hoses and the angle of the XS tubes wasn't right. Its obviously a patch up and it rubbed on my frame. What I offer costs a lot more because its custom made specifically for Nortons. I went to some trouble designing it to fit the various applications and bolt on without having to drill holes in your cases (but you can go ahead and drill for the sump breather if you don't have Combat or Maney cases).

Jim NH
If you get your Norton hot and put a lot of miles on it - you will probably see some oil weeping at the joints. If not then you have an exception. The reed valve gives you an advantage in the battle for an oil tight Norton. Some people claim a HP gain.
I don't think it would amount to much.
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Re: NEW reed valve breather fits all Commandos?

Postby pantah_good » Thu Apr 20, 2017 11:51 am

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