Jubilee Crankcase breather

Forums

Help all

I’ve nearly finished my build but I’m missing the crankcase breather. I can’t for the life of me find the right part. The original part number is shown as 25094. Not knowing what it looks like doesn’t help either.

does anybody have a link to where I could get one or even better have one they would be willing to sell.

Breather pipe 25094

Hi Paul,

This part number is listed for the very last Lightweights. You might confirm yours is '64 onwards.

I've seen a few later Lightweight crankcases and this breather pipe has been fitted above the gearbox sprocket. I've never seen the pipe separated from the crankcase and I'm sure most times it is deemed an inseparable assembly.

Norton drawing 24723, the machined Drive Side crankcase for late lightweights, gives us a clue.

Drawing below. Breather area.

Check with a 0.25 ins drill that the hole for the crankcase breath is clear and free from obstruction.

Note that the first 1.0 ins of this hole is enlarged and reamed to .308/.309 ins diameter.

From memory I believe the breather pipe is copper and sticks out about 2 1/2 inches.

From the drawing I can see that one inch of the pipe is pressed into the crankcase. I can only guess, because I have no drawing of the breather pipe. I'm guessing copper pipe, 5/16ins outside diameter, and 3 1/2 inches long. Pressed into the crankcase and never usually comes out.

You may find you get a good result by easing the fit a little and using a 'Loctite' which will stop leaks around the tube.

Most times the copper pipe is bent a little upwards after fitting to make sure the pipe clip for the rubber breather tube clears the drive chain and is more accessible.

Hope this helps and maybe someone has some good photos of the tube in situ.

Peter