Oil Tank Breather Diameter

[swooshdave]

Any idea why the difference? The only thing I can think of is the bigger breather a from a MkIII? Thoughts?

 

[L.A.B.]

Any idea why the difference? The only thing I can think of is the bigger breather a from a MkIII?

Yes (tank spigot). https://andover-norton.co.uk/en/shop-drawing/879/oil-tank-and-fittings-oils-lines-cartridge-filter#

 

[Ron L]

When the side mount oil tank was introduced (1971) the timed breather from the cam was used. The diameter of this breather matched the fitting on the oil tank. In 1972, the breather was moved to the rear and had a larger hose fitting. Norton continued to use the same oil tank and fitted the silly metal reducer in the hose near the tank so a smaller hose fit the tank inlet. It wasn't until the MkIII introduction that they did away with the adapter and used the larger inlet on the tank.

Maybe they had a large stock of oil tanks to use or perhaps they would have had to raise the filler neck to fit the larger hose fitting? Or perhaps they were concerned that the larger hose would create a clearance problem that would put the already compromised tank mounts into stress? Who knows?!

 

[kommando]

Maybe they had a large stock of oil tanks to use or perhaps they would have had to raise the filler neck to fit the larger hose fitting? Or perhaps they were concerned that the larger hose would create a clearance problem that would put the already compromised tank mounts into stress? Who knows?!

More likely they forgot and then when the first ones went down the line added the metal reducer instead of modifying the tank.

 

[swooshdave]

Why this came up is my brother was installing the NYC sump breather and couldn't figure out why the hoses didn't match up. His bike is a bit of a mongrel and have a smattering of MkIII parts on it although the engine is a 73. He didn't realize he has the MkIII tank and should have ordered the correct kit for the later tank from @Holmeslice

Luckily he had put the Comstock sump on my Interstate a while ago and found the reducer which he can now use by flipping it around to work the the MkIII oil tank. So it should all work out.

 

[Holmeslice]

This is the main difference in our '75 Breather kits from the rest of the years - The MK3 kit comes supplied with a 1/2" banjo and appropriate hose to fit directly to the MK3 tanks.

Dave, have your brother reach out and I'll take care of him.

Stay safe, folks.

-Kenny

 

[swooshdave]

This is the main difference in our '75 Breather kits from the rest of the years - The MK3 kit comes supplied with a 1/2" banjo and appropriate hose to fit directly to the MK3 tanks.

Dave, have your brother reach out and I'll take care of him.

Stay safe, folks.

-Kenny

We're all good, you're the one who needs to stay safe!