About a chaincase breather.

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Transmission cap has a small hole to allow venting of oil pressure.
Don't you think it would be useful to practice the same small hole (or even slightly more) on one of three outer chaincase caps?.

Ciao.

Piero
 
Piero, in my opinion not necessary to drill a breather hole in the primary chaincase.
The chaincase can breath via the felt washer where the gearbox mainshaft enters the primary chaincase.
 
2+ = plenty of venting for such little pressure changes though one place most forget is also destined, if not designed to vent is the seam of air space around the last outer sleeve shaft bush. No oil seal needed there d/t no oil ever really gets that far in those bushes. Its not bad id to change gear lube or ATF every few years and for sure soon after a rebuild.
 
Correctly filled, there is actually not very much oil in the primary case. The Mk3 850 has proper oil seals but I've never been aware of a pressure build up.

The gearbox breather allows water to get in but I'm not sure what else it achieves... :roll:
 
Not the worse cheap item to get the job done a while.
About a chaincase  breather.


8/22/2013 7:55 AM

I have the unknown plastic Motor mite power brake check valve on my Triumph,
XS650 and SR500. The Triumph is on the longest but all are still functioning
after years of use. The SR is a big single, 540cc, and oil tight. This bike
actually holds vacuum after I shut it down so I'm not sure a simple breather
tube or installing an air bleed would be better.
Tom Grahm tomterrific7@sbcglobal.net

8/22/2013 9:05 AM

I have used the automotive powerbrake check valves on my British bikes for over 40 years. The first was one of my Vincent Black Shadows. I tested it with a vaccum/pressure meter in the line between the engine and the check valve. When starting the motor the meter was on the pressure side. After @10 seconds the vaccum settled at @ -2psi and stayed there.

John Mead john.mead@prodigy.net
 
I'd venture to say most who are running some type of reed valve breather have already tried the Motormite, with unsatisfactory results. I know I did. If the Motormite is so effective why did Jim Comstock go through all the time and expense to develop his reed valve?
 
I'd venture to say most who are running some type of reed valve breather have already tried the Motormite, with unsatisfactory results. I know I did. If the Motormite is so effective why did Jim Comstock go through all the time and expense to develop his reed valve?

Count me as at least one very satisfied Motormite valve in my breather line customer

in fact, I have had the same one in place now for going on three years for the $9 cost, still no leaks

cheap and effective, what's not to like?
 
1up3down said:
I'd venture to say most who are running some type of reed valve breather have already tried the Motormite, with unsatisfactory results. I know I did. If the Motormite is so effective why did Jim Comstock go through all the time and expense to develop his reed valve?

Count me as at least one very satisfied Motormite valve in my breather line customer

in fact, I have had the same one in place now for going on three years for the $9 cost, still no leaks

cheap and effective, what's not to like?

Are you running a primary belt drive?
 
No breather is needed for the chaincase. You are also better off to use a little epoxy and plug the tiny hole in the transmission inspection cover. It is not needed and is a good way to let water into the trans when it rains or you wash the bike. Jim
 
JimC said:
I'd venture to say most who are running some type of reed valve breather have already tried the Motormite, with unsatisfactory results. I know I did. If the Motormite is so effective why did Jim Comstock go through all the time and expense to develop his reed valve?

I have seen some motormite valves that seemed to last a while but I have also seen them that had the rubber seal inside come apart.

But in answer to your question I wanted a breather that would actually create a depression in the crankcase instead of just a relief valve that opens after the pressure rises. Jim
 
it's been my experience that the Motormite gives up the ghost after a few hundred miles. I verified this by finding oil in my primary case,; I run a belt. If you have a chain drive primary I doubt you'll know it that crankcase seal is passing oil. I can assure you, with a reed valve PCV valve the primary case runs dry. BTW, the Norton clutch original design was meant to run dry. Clutches depend upon friction. Oil reduces friction. If you have oil in your primary you are at cross purposes.
 
Hehe, at times this is a confusing list Jimmy. Re-read builder Mead comment of lowering case pressure 2 pis and holding. Now think about this a moment... ...
If his MotorMite was not seeing engine piston pressure pulses from the crank case how could it lower PSI by passive action? John Mead is decades repeated vintage race builder, not a shade tree like me. To be cute yet logical, the success stories of MotorMite implies those that didn't - ain't quite up to full speed on its complex installing issues. It also implies that some builders engines' blow by is more than a mere MotorMite can cover up. There's comments that these valves must be close to the crank case to work right, well I didn't do mine close as its a natural slip in where Combat hose turns horizontal to tank with a reduced dia hose. Worked fine for the blow by on my 1st ever engine. When ring blow by hit my Trixie even her Dreer $100 Krank PCV couldn't keep up.
 
Are you running a primary belt drive?

yes, I am, completely dry

and yes, my Motormite check valve been in place stopping leaks for around three years now
 
hobot said:
Hehe, at times this is a confusing list Jimmy. Re-read builder Mead comment of lowering case pressure 2 pis and holding. Now think about this a moment... ...

OK Stevie,
Put an absolute pressure sensor in the tach drive hole -no connecting hose to mess with the readings and connect it to a scope so you can see what is happening in the crankcase. Then put your breather valve on the timing chest and see what you get. Make sure and look in the 3 to 5,000 rpm range where a Norton motor spends most of it's life and vary the load. Any one way valve will create some depression at idle. The pressure pulses in the cases might surprise you. Jimmy
 
I've saved your posts on the pressures and power released. All's I know is on mine and others oil leaks were not an issue until something dramatic occurred unrelated to PCV. Peel's got brownish and appeared to be decaying in a few seasons but then Dreer sweet talked me into the Krank. MotorMite seems a lighter valve than the Krank so would think MM might work a bit better though not as long or looking cool as a shiny alloy Krank. I'm mostly aware of inertial aspects of the various flappers and new age materials and smaller case volumes avoiding passage pumping to impart a stronger impulse close to the valve - just don't know what circumstances those details become functional road significant, as opposed to in shop instrument measured. Am I wrong to think that that main advantage is just getting away with more blow by? This is good feature of course, but what's it imply about state of various engines that do benefit with more effective PCV?

Once cases are somewhat below ambient then what difference does it make if its 1.5 or 5.5 lb, except the lower may turn crank seal inside out and all out race engines [in our size-type] can gain a couple-3 hp. Its annoying to reflexly imply that those using the motormite successfully for a long time are somehow doing something wrong or they could detect a road use difference with a pound or 2 lower pressure. Krank sells a bunch and if didn't work about as advertised don't ya know the word would go around quick. Here's a mental static humor from hobot view point > I'd recently posted the more robust and effective-efficient reed valves alternatives to others to use - then got shot back the 2 posts from Tom and John as a kind of poke at me on advertising such over kill devices. sheeze.

hehe, fact is I don't think any the passive valves are good enough for Ms Peel but just fine for the rest of ya :?


About a chaincase  breather.
 
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