Which is the best "Comnoz" breather??
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DogT
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I understand 4 ways to install breather for bikes with timed breather on the left side of engine.
1. Original. Hose off left side of crankcase to top of oil tank.
2. Jim Comstock sump breather. His valve installed in sump plug, hose goes to top of oil tank. About $230 plus shipping. Can drill hole below oil pump.
3. Install breather valve in blanking plate like swooshdave. Block breather hole in left side of engine with bolt. Hose from breather valve to top of oil tank. Drill one hole below oil pump into crankcase.
4. Breather valve installed at rear of engine crankcase. Hose goes to top of oil tank. Drill hole below oil pump, and extra holes like picture for air flow from crankcase into timing chest. This requires machining the engine crankcase and is a special operation done by machine shop like Hemmings or CNW.
The oil tank breather can be hose into air at rear of bike, or into catch bottle with any of these methods. I prefer catch bottle. I am using my original breather like #1.
Correct me if I am wrong.
Dave
69S
1. Original. Hose off left side of crankcase to top of oil tank.
2. Jim Comstock sump breather. His valve installed in sump plug, hose goes to top of oil tank. About $230 plus shipping. Can drill hole below oil pump.
3. Install breather valve in blanking plate like swooshdave. Block breather hole in left side of engine with bolt. Hose from breather valve to top of oil tank. Drill one hole below oil pump into crankcase.
4. Breather valve installed at rear of engine crankcase. Hose goes to top of oil tank. Drill hole below oil pump, and extra holes like picture for air flow from crankcase into timing chest. This requires machining the engine crankcase and is a special operation done by machine shop like Hemmings or CNW.
The oil tank breather can be hose into air at rear of bike, or into catch bottle with any of these methods. I prefer catch bottle. I am using my original breather like #1.
Correct me if I am wrong.
Dave
69S
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When using either of my breathers you do not want to drill any extra holes into the timing chest for breathing. Our full modification involves plugging any holes that are there. This makes the crankcase volume smaller so the reed works more efficiently.
There is an older recommendation for a modification that involved drilling extra holes between the chaincase and crankcase but I did not find that to be of much value. It also weakens an area that is highly stressed.
It is still acceptable to drill the extra oil drainback hole no matter which method is used for a breather. Jim
There is an older recommendation for a modification that involved drilling extra holes between the chaincase and crankcase but I did not find that to be of much value. It also weakens an area that is highly stressed.
It is still acceptable to drill the extra oil drainback hole no matter which method is used for a breather. Jim
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DogT said:
Just to be clear I just posted a pic and link another post. Not my bike.
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pierodn said:
I suggest you click on the link I provided after the picture. That thread will give you more info.
DogT
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I'll make it easy on Piero so he doesn't have to read through all that English.
http://www.mikesxs.net/product/15-0677.html
http://www.oldbritts.com/11_061542.html
Dave
69S
http://www.mikesxs.net/product/15-0677.html
http://www.oldbritts.com/11_061542.html
Dave
69S
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DogT said:
I don't think that made it easier... :mrgreen:
DogT
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I'm not sure either. Mike's breather doesn't look like the one in the picture and where would Piero get a Motormite # 80190 unless someone in the US sent him one? Certainly someone over the pond has done this breather mod. I'd suggest he email Andover or Norvil about a reed valve, since Hemmings won't email. Maybe one of you EU guys can help him?
Dave
69S
Dave
69S
Piero,
the 72 750 breather is what you're looking for : http://www.nortonmotors.de/ANIL/Norton Website/norton/parts-list.php?Model=n750_1&Plate=004&Part=47 part 47 to 53 .
This can be ordered from Andover Norton .
Instead of having it on the bottom of the crankcase , put it on the blanking plate, neat mount and nothing than can't be put back in original condition.
This breather will be better than the camshaft mounted one , but does not include any valve, you have to add an on line valve . You can use modern Ducati breather valve for this, easily available in Italy .
the 72 750 breather is what you're looking for : http://www.nortonmotors.de/ANIL/Norton Website/norton/parts-list.php?Model=n750_1&Plate=004&Part=47 part 47 to 53 .
This can be ordered from Andover Norton .
Instead of having it on the bottom of the crankcase , put it on the blanking plate, neat mount and nothing than can't be put back in original condition.
This breather will be better than the camshaft mounted one , but does not include any valve, you have to add an on line valve . You can use modern Ducati breather valve for this, easily available in Italy .
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This is how I did Ms Peel -[with cast solid area here] moved that factory Combat breather baffle to the magneto area but also drilled three 1/2" holes in TS case to lower pumping loss and allow free flow vapors from crank cases into TS then out the breather. Peel was immaturely used into red line often and survived a cold start tachometer needle disappearing over rev event - yet - a white tissue rubbed in the big breather tube didn't even bring up slight oil mist evidence inside its always clean and clear tube. Before I had the wisdoms of reed valve and its plumbing mods, I used my own reasoning to enlarge the volume blow by was trying to pressurize. To me by far the main benefit of moving the Combat baffle off its factory location was ease of gearbox removal w/o having to tip engine forward so gearbox could twist right out. Jim found that lowering oil level in TS case significantly lowered TS case temps, so oil was not dumping it heat to cases as much, which may or may not be desirable. Extra low inside pressure by extra efficient flapper valve - beyond just oil tightness needs would help seal rings from blow by and help lower the flash off temperature of moisture in the oil [aka: vacuum distilling].
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pierodn said:
The breather on the 1972 engines is not a valve. Items 46-53 (or so). It's just a tube with some gauze. I don't know what it's suppose to do. :mrgreen:
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The Combat breather fitting is mainly just to hold a hose on and to much lessor extent acts as a baffle to keep some oil mist out of the breather hose, but garantee by crank sling and cold idle blow by > it pumps way more oil back to tank during the 30 seconds or so it takes the wet sump oil to empty down till oil pump and can handle it. A reed-flapper valve mounted on the magneto area would both baffle some and vent one way. Combats have front oil pick up so tend to pile oil up on held hi throttle the lesser models don't have same issue with. A home made plate and gasket + sealant would work as well as store bought plate.
It the cheap inline Brake valve on expense inline Krank PCV valve don't work an oil tight treat then consider a new ring-bore job and air filter is in order or spend more and diddle a bit more for the the flapper valve and put off ring job a bit longer. I'd think if a PCV put in it would be better to block the timed breather so it don't back flow some to nullify the lower pressure.
It the cheap inline Brake valve on expense inline Krank PCV valve don't work an oil tight treat then consider a new ring-bore job and air filter is in order or spend more and diddle a bit more for the the flapper valve and put off ring job a bit longer. I'd think if a PCV put in it would be better to block the timed breather so it don't back flow some to nullify the lower pressure.
DogT
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I think what Piero needs to do is make or buy a right angle hose fitting that will bolt into his 71 blanking plate. It could simply be a right angle fitting for a 3/8" hose, not unlike the right angle fitting on the left side crank case, maybe he could even use that one since he's going to block it off anyhow (it's actually a 7/16" but a 3/8" hose will fit on it). Then buy a Ducatti breather valve and put next to the pipe fitting in the rubber hose. Unless he can figure out how to put the valve into the right angle fitting? I think that's what Old Britts did with the Motormite brake valve. They glued it into the 72 breather as near as I can tell.
That should work, no?
Dave
69S
That should work, no?
Dave
69S
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Yep Dave that'd do it and epoxy more is than good enough for this job. If ya don't like the check valve clutter down there it still works good enough up under seat near the tank. I bet just a boat duck bill scupper valve on end of the oil tank vent tube would do the oil tight job too.
Thank you very much for the advice but I eventually ideas more confused than at the beginning.
Therefore, I decided to leave the breather standard on left side of the crankshaft.
My first idea was to close the original vent and move the same breather on the blanking plate after drillec a 1/4 hole under the left side of the oil pump.
But I got too much information and I'm lost in translations.
Ciao.
Piero
Therefore, I decided to leave the breather standard on left side of the crankshaft.
My first idea was to close the original vent and move the same breather on the blanking plate after drillec a 1/4 hole under the left side of the oil pump.
But I got too much information and I'm lost in translations.
Ciao.
Piero
Hi Pierodn,
My Commando is a 1971 with the breather on the left side of the engine. I'm going to get Jim Comnoz's breather which replaces the sump plug under the engine. Put the hose off the old breather onto it and screw a bolt in to seal up the old breather. I'm not going to drill any holes and can put it all back to original if I want to.
Graeme
My Commando is a 1971 with the breather on the left side of the engine. I'm going to get Jim Comnoz's breather which replaces the sump plug under the engine. Put the hose off the old breather onto it and screw a bolt in to seal up the old breather. I'm not going to drill any holes and can put it all back to original if I want to.
Graeme
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