Crank case breather

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A few posts back Jeandr says they are $220 I don't know if this is the same kit as for the 72 however. I have the old breather spot on the rear of the case blanked off at this time and opened on the timing side, Sounds like I should have done it with the CNW kit, Damn. :roll:
 
Hi Guys,

We are just ready to put the breather kits up on our web site. Since Jim Comstock designed them and we went into production we have installed and ran about 12 units and they have performed extremely well.

Sure there are some other approaches to deal with the crank case pressure, and we are well aware of the fact that this kit is not inexpensive, but this kit works. Others we have used really did not perform like we needed them to. When Jim showed us the results he had experienced, we didnt hesitate to bring it to the market. We have been fortunate to work with Jim for years and I hope that he will keep developing upgrades and modifications as there is no question that its pretty amazing stuff. All to make the Commando a better machine.

We have a kit that will retail for 265.00 and that includes the machining of the drive side case half, all modifications done to the timing side case, the valve, cnc machined body, gaskets and hardware. All you need to hook it up is a hose from the valve to the oil tank. We have two different sizes of spigots. 1/2 for the MKIII's and a 3/8 for the other models.

We also have a kit that will bolt directly to the -72 style breather mount on the lower back side of the engine case. This kit will run 220.00 and includes a cnc machined adaptor, valve, cnc machined valve body, gaskets and hardware.

I did see a post that mentioned different prices than listed above. This would indicate that we did more services to the engine such as clean, blast, prep, main bearings or other wise.

Another important point is that we do not offer any numbers as far as horse power increases. This is due to the fact that every engine is different and the end result depends on many factors. As Jim mentioned, the valve was designed to deal with crank case pressure.

I am not trying to use this forum to push sales but rather to make sure the right information was out there in regards to prices.

Thanks

Matt / Colorado Norton Works
 
Hi , is there any advantage to get rid off the disc bearing cover in the timing side case, that could improve gases/air communication between cases and timing cover ????????
 
Marineatlas, from what Jim says and the way it is done by CNW, the timing chest must be as closed as possible to keep crankcase volume as low as possible, this lets the reed valve work better and lets it create a slight vacuum in the crankcase. The vacuum keeps the bike oil tight and possibly improves power.

Jean
 
This is very interesting and makes me wonder, since I have a 72 Combat, whether I should move my Ducati reed valve from the timing case back to the original mount on the back of the crankcase.

In fact, this is where it was until I had chance to take the engine apart and do the machine work. It dealt with the oil leaks even then, but not of course the incorrect oil pickup. Until I moved the oil pickup you could see much oil returning through the breather when over 4000 rpm.

The theory on crankcase compression and the inertia of columns of air under pulsed conditions is sound and is exactly why two-strokes make so much power but only over relatively narrow rpm ranges (I've had many two strokes, including an awesome RG500 Suzuki, but it was too much of a licence loser).

Best regards, Phil.
 
Re:

CNW said:
Hi Guys,

We are just ready to put the breather kits up on our web site. Since Jim Comstock designed them and we went into production we have installed and ran about 12 units and they have performed extremely well.

Sure there are some other approaches to deal with the crank case pressure, and we are well aware of the fact that this kit is not inexpensive, but this kit works. Others we have used really did not perform like we needed them to. When Jim showed us the results he had experienced, we didnt hesitate to bring it to the market. We have been fortunate to work with Jim for years and I hope that he will keep developing upgrades and modifications as there is no question that its pretty amazing stuff. All to make the Commando a better machine.

We have a kit that will retail for 265.00 and that includes the machining of the drive side case half, all modifications done to the timing side case, the valve, cnc machined body, gaskets and hardware. All you need to hook it up is a hose from the valve to the oil tank. We have two different sizes of spigots. 1/2 for the MKIII's and a 3/8 for the other models.

We also have a kit that will bolt directly to the -72 style breather mount on the lower back side of the engine case. This kit will run 220.00 and includes a cnc machined adaptor, valve, cnc machined valve body, gaskets and hardware.

I did see a post that mentioned different prices than listed above. This would indicate that we did more services to the engine such as clean, blast, prep, main bearings or other wise.

Another important point is that we do not offer any numbers as far as horse power increases. This is due to the fact that every engine is different and the end result depends on many factors. As Jim mentioned, the valve was designed to deal with crank case pressure.

I am not trying to use this forum to push sales but rather to make sure the right information was out there in regards to prices.

Thanks

Matt / Colorado Norton Works
Click to expand...

To set the record straigh, one set of parts was missing from my friend's order, Matt sent him the parts so everything checks out. The $220 kit is made for the Combat motors, it has an adapter plate and can be installed without any case machining.

Jean
 
Here is my blatant copy of what CNW sells, the reed is from one of their kits, but I have one exactly the same on the way, I found it on e-bay for $20 delivered. Next order of business is to get the crancases modified, unfortunately, I can't do it myself because I don't have a big milling machine, only a homemade lathe attachment.

Jean

Crank case breather

Crank case breather
 
BMW has a reed valve to replace the flaper valve on the old twins, /5 /6 /7 series. It's about 1 1/4 to 1 3/8" in diameter, they are not expensive. I made a container from some aluminum pipe, alittle machine work and welding were required. I did not alter the engine at all so it can go back to stock. I just installed it between the engine and oil tank. It's about 1 1/2" in diameter and 2" tall. It works well, I think the Mighty mite does not have enough volume. The Yamaha set up is nice, (more machine work) mabe more efective, and more expensive. I made mine from stuff I had around. It's been on there for about 15 years with no probblems.

Ken G.
 
The Yamaha valve is sixteen bucks, hardly expensive. The only additional materials required are a 1/4 bolt and some breather hose. No machining or welding required. As for it's efficacy, I can only say it stopped the crank seal leak and any other leaks I had. As for increase in power, I just wheelied past a 1098 Ducati. Did I mention the Duke was parked?
 
Re: crank case breathers

Fullauto said:
Yeah, but you've got to remember that you are still sucking a crankcase full of air in at every upstroke. What it means is that your engine is a big air pump both ways, ie. top and bottom of your pistons. Takes power to do that.
I suspect that early Jap twins weren't oil tight because of superior quality but because they used 180 degree cranks. Therefore, the crankcase volume didn't change because as one piston was going up, the other was going down.
Click to expand...

I'm new to the Commando and a long time Triumph man. I've got a 74
Mk2A and have some annoying smoking going on and have given some thought to the breather. My question is: doesn't it take power to build a vacuum from BDC when the valve closes and the pistons start to move up? It seems to me that minimal power might be used if the vent was so big there was little resistence to flow in and out. I had never heard any talk of these valves in the breather prior to getting on this forum.

Bill G.
 
Not sure if it's in this thread or another, but the developper of the kit for CNW, Jim Comstock, said there was an increase in power with this kit in place and he got even more power when a vacuum pump was hooked up to the crankcase, all this makes sense because the spinning crank uses a lot of power just rotating inside an air filled chamber, if the air was removed, the crank would spin easier. The bonus with a reed valve is keeping the oil inside instead of trying to pump it out onto the road.

Unless you have a lot of time on your hands and a well equipped shop, send your stuff to CNW, they do it right.

Jean
 
If you block off all the holes to the timing chest will the gears and the cam chain get enough oil spray?
 
mcns said:
If you block off all the holes to the timing chest will the gears and the cam chain get enough oil spray?
Click to expand...

Jim Comstock says the gears and chain will be well lubricated, he also said before there was too much oil and the oil would just be whipped to a froth. He did tests with a clear cover and saw what was happening and devised his hole placement from those tests. All logical to me :D

Jean
 
Re:

JimC said:
The Yamaha 650 XS crankcase breather . Far superior to the oft mentioned Mity Mite brake vacuum check valve. http://www.mikesxs.net/products-40.html#products Part #15-0677.
Click to expand...
Jim
I have a 69 750 and I put the Mike's reed valve inline because I wanted to eliminate the chain oiler tube, but what I've noticed is when I block the oiler tube even with the reed valve my bike blows oil out of every orifice. I'm not sure the reed valve makes any difference if I have the oiler tube open. I read somewhere here that early Commando have a type of one way valve in the engine where the breather hose exits and they don't really benefit from the reed valve. You are the expert so what's the story on the early Commandos?
THX
Bruce
 
Re: Re:

69750S said:
JimC said:
The Yamaha 650 XS crankcase breather . Far superior to the oft mentioned Mity Mite brake vacuum check valve. http://www.mikesxs.net/products-40.html#products Part #15-0677.
Click to expand...
Jim
I have a 69 750 and I put the Mike's reed valve inline because I wanted to eliminate the chain oiler tube, but what I've noticed is when I block the oiler tube even with the reed valve my bike blows oil out of every orifice. I'm not sure the reed valve makes any difference if I have the oiler tube open. I read somewhere here that early Commando have a type of one way valve in the engine where the breather hose exits and they don't really benefit from the reed valve. You are the expert so what's the story on the early Commandos?
THX
Bruce
Click to expand...

You have a timed breather already. Where did you put the reed valve?
 
Bruce,

While I don't claim to be an expert, I will share my experience. In answer to your question about early Commandos, to the best of my knowledge, 71 and earlier had a timed breather. It was a rotary disk at the end of the drive side of the camshaft (item #46). I had a 69 Commando, but I don't remember how effective the rotary vent was. On my 72 Combat I use a Mike's XS 650 PCV valve which is very effective. Originally, I thought it was a stock part from a Yamaha XS 650. Later it was pointed out this was not the case. It's origins are rather dubious.

If your Commando blows oil with a reed valve, I suspect a plumbing error. Almost sounds as if you've hooked it up backwards. Then again, I have no idea what happens when you use a timed breather and a reed valve PCV together.

Crank case breather
 
Re: Re:

swooshdave said:
69750S said:
JimC said:
The Yamaha 650 XS crankcase breather . Far superior to the oft mentioned Mity Mite brake vacuum check valve. http://www.mikesxs.net/products-40.html#products Part #15-0677.
Click to expand...
Jim
I have a 69 750 and I put the Mike's reed valve inline because I wanted to eliminate the chain oiler tube, but what I've noticed is when I block the oiler tube even with the reed valve my bike blows oil out of every orifice. I'm not sure the reed valve makes any difference if I have the oiler tube open. I read somewhere here that early Commando have a type of one way valve in the engine where the breather hose exits and they don't really benefit from the reed valve. You are the expert so what's the story on the early Commandos?
THX
Bruce
Click to expand...

You have a timed breather already. Where did you put the reed valve?
Click to expand...
The reed valve (Mike's XS valve) is up near the oil tank.
Jim and Swoosh
Thx for the fast reply. To answer the plumbing w/o removing the side cover I think the large port was toward the breather and the small outlet towards the tank. I had to cut a 45/70 brass cartridge for a ferrule to make the connection to the breather side hose as it was about 1/2 inch in diameter and the outlet side was about 7/16 but I managed to squeeze the 3/8 hose on it. Air would only blow from one direction (large to small outlet) so I positioned it so it would allow air out but not back in. I tried the Mity Mite but both valves I bought would allow air to flow freely in both directions.
Perhaps my connections are not airtight enuf. I had to use an adaptor I bought that was a 1/2 by 7/16 rubber elbow on the breather side and I couldn't get a hose clamp on one side as there wasn't much room, but I thought it was a tight fit.
 
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