Oil tank breather line question

Status
Not open for further replies.
Joined
Oct 5, 2012
Messages
168
Oil tank breather line question


This OB diagram shows the oil tank breather line going into a a T fitting between the 2 carbs. I'm pretty sure mine just had a line connecting the 2 carbs with no T fitting. So where then is the oil tank breather line supposed to go?
 
On my '74 it goes to a pipe on the back side of the air filter mounting plate. Overfill the oil tank and your air filter gets saturated with oil :(
 
Robb2014 said:
This OB diagram shows the oil tank breather line going into a a T fitting between the 2 carbs.

Only black airbox 850 Mk.1A (possibly?), 2A and Mk3 models had that breather arrangement (the drawing is from the 850 Mk3 manual)


Robb2014 said:
I'm pretty sure mine just had a line connecting the 2 carbs with no T fitting. So where then is the oil tank breather line supposed to go?

To a pipe on the back plate of the metal airbox.

http://www.oldbritts.com/1973_g12.html
 
I have a different setup (central oil tank) and I routed my oil tank breather to a catch bottle. Much better solution in my opinion. It would be easy for you. I had to make a project out of it because my oil tank breather goes right into the air filter with no hoses, it's integral in the oil tank. I've been thinking about blocking it and adding another breather port in the top of the tank.

Dave
69S
 
maylar said:
On my '74 it goes to a pipe on the back side of the air filter mounting plate. Overfill the oil tank and your air filter gets saturated with oil :(

Mmmm nice, especially as fun as it is changing that filter. Does anyone ever just run a dump out the back some place?
 
DogT said:
I have a different setup (central oil tank) and I routed my oil tank breather to a catch bottle. Much better solution in my opinion. It would be easy for you. I had to make a project out of it because my oil tank breather goes right into the air filter with no hoses, it's integral in the oil tank. I've been thinking about blocking it and adding another breather port in the top of the tank.

Dave
69S

How big a bottle would you suggest?
 
Robb2014 said:
maylar said:
On my '74 it goes to a pipe on the back side of the air filter mounting plate. Overfill the oil tank and your air filter gets saturated with oil :(

Mmmm nice, especially as fun as it is changing that filter. Does anyone ever just run a dump out the back some place?


Yes you can do that but it can get messy and basically mists your bike with oil. I opted for a catch bottle.

Here is a thread on catch bottles.

catch-bottles-t14100.html
 
drones76 said:
Robb2014 said:
maylar said:
On my '74 it goes to a pipe on the back side of the air filter mounting plate. Overfill the oil tank and your air filter gets saturated with oil :(

Mmmm nice, especially as fun as it is changing that filter. Does anyone ever just run a dump out the back some place?


Yes you can do that but it can get messy and basically mists your bike with oil. I opted for a catch bottle.

Here is a thread on catch bottles.

catch-bottles-t14100.html

Thanks for the info all... catch bottle it is.
 
In 1K miles I have less than 1/4" in my large pill bottle catch can. I bought one of those AL cans like drones, am trying to figure a way to add a new breather to the tank and use it. No matter where you dump the oil, it makes a mess. Better to contain the oil.

Oil tank breather line question


I tried dumping it down below the centre stand and it was all over the bottom of the bike back to the rear wheel.

Dave
69S
 
DogT said:
In 1K miles I have less than 1/4" in my large pill bottle catch can. I bought one of those AL cans like drones, am trying to figure a way to add a new breather to the tank and use it. No matter where you dump the oil, it makes a mess. Better to contain the oil.


I tried dumping it down below the centre stand and it was all over the bottom of the bike back to the rear wheel.

Dave
69S

I've got about 4 inches of extra space in my battery compartment. Looks like we're having beans for lunch tomorrow, or maybe tomato soup... easier to get out of a 3/8 inch hole in the top of the can.
 
Robb2014 said:
maylar said:
On my '74 it goes to a pipe on the back side of the air filter mounting plate. Overfill the oil tank and your air filter gets saturated with oil :(

Mmmm nice, especially as fun as it is changing that filter. Does anyone ever just run a dump out the back some place?


im now running a line to the rear of the lic plate. works good on the last 200 miles. Not a drip on my tire or mist on the rear area. its working great for me so far.
 
iceteanolemon said:
im now running a line to the rear of the lic plate. works good on the last 200 miles. Not a drip on my tire or mist on the rear area. its working great for me so far.

That's how it was done before the first air quality regs. On Triumph they had a silver-colored hose that ran down the left side of the rear fender. My P11 has the hose run around the inside of the fender from the oil tank to just below the license plate.

I used to work on old cars, and in the days before PCV valves, crank case venting was done via a 'road draft tube', typically a steel tube that ran from the lifter galley down past the transmission, where it was open to the road.

Oil tank breather line question
 
BillT said:
iceteanolemon said:
im now running a line to the rear of the lic plate. works good on the last 200 miles. Not a drip on my tire or mist on the rear area. its working great for me so far.

That's how it was done before the first air quality regs. On Triumph they had a silver-colored hose that ran down the left side of the rear fender. My P11 has the hose run around the inside of the fender from the oil tank to just below the license plate.

I used to work on old cars, and in the days before PCV valves, crank case venting was done via a 'road draft tube', typically a steel tube that ran from the lifter galley down past the transmission, where it was open to the road.

Oil tank breather line question

The crankcase venting of the Paralell twin is more challenging than a 4-6-8.. two rising and falling together, versus some headed up, while others headed down. Add to that a very small crankcase (dry sump) and there's more than just blow-by gases, it's a suck-blow storm.
 
well with all this being said I think I may "upgrade" and add a small air filter to the hose.... Other than that its a done deal for me!!
 
DogT said:
I have a different setup (central oil tank) and I routed my oil tank breather to a catch bottle. Much better solution in my opinion. It would be easy for you. I had to make a project out of it because my oil tank breather goes right into the air filter with no hoses, it's integral in the oil tank. I've been thinking about blocking it and adding another breather port in the top of the tank.

Dave
69S

Hi Dave
Methinks you may have hit upon the ideal solution for us central- oil- tankers. And the timing is perfect for me: my oil tank is on the work bench right now. I'll see if I can add that extra breather port as a back-up plan, in case the timing case breather I am working on puts out too much oil to be routed directly to the catch tank. If I have to route it back to the oil tank, that extra port will be needed.
I'm guessing that your intention is to route the breather to the air filter via the catch bottle, since you already have the hole in the air filter plate?
Cheers
Martin
 
MFB said:
I'm guessing that your intention is to route the breather to the air filter via the catch bottle, since you already have the hole in the air filter plate?
Cheers
Martin
I was just going to take the new oil tank breather port and take it to the catch bottle and let it breathe to the air. No intention of routing anything into the air filter/carb intakes.

I have an extra oil tank I was thinking about operating on at some point. There's a slight difference as to where the timed breather tube goes on each one, I'm thinking my original one is older, that breather tube goes to the top hat thingie.

Dave
69S
 
DogT said:
I have an extra oil tank I was thinking about operating on at some point. There's a slight difference as to where the timed breather tube goes on each one, I'm thinking my original one is older, that breather tube goes to the top hat thingie.

Dave
69S

That's interesting. Norton must have fiddled with the details on this tank for some reason. My tank must be like your extra one. The pipe for the timed breather comes out the top of the tank next to the top hat then bends 90 degrees to face left/rear about 45 degrees. I haven't decided where to place the extra port yet - maybe in the top hat if space permits?

Cheers
Martin
 
Status
Not open for further replies.
Back
Top