Crankcase breather

[sunalp2]

I've done a search, with no results.

Where is the breather located on the model 20 engine?

I have a feeling mine os either blocked, or not working.

[petert120r Profile]

It's a flap valve inside the large nut securing the primary sprocket to the crankshaft

[dave16mct Profile]

On the earlier twin (1950) like yours it would be a timed breather driven by the inlet camshaft. You should be able to see the rubber tube from it behind the barrel at the back of the chaincase. See page 18 of your 1950 owners manual. You may also have the flapvalve on the end of the crank if the crank has been replaced with a later one.



http://archives.jampot.dk/book/Owners_m ... Manual.pdf

Dave.

[sunalp2]

On the earlier twin (1950) like yours it would be a timed breather driven by the inlet camshaft. You should be able to see the rubber tube from it behind the barrel at the back of the chaincase. See page 18 of your 1950 owners manual. You may also have the flapvalve on the end of the crank if the crank has been replaced with a later one.



http://archives.jampot.dk/book/Owners_m ... Manual.pdf

Dave.

Sorry Dave, my signature is a bit misleading. My 1950 18s frame has a 1954 Model 20 motor and gearbox.

The reason I'm asking this question is that I've recently done the oil seal mod to stop oil going into the probary tank, and all of a sudden the engine is blowing smoke.

[ajscomboman Profile]

Breather on the crankshaft bolt is the first place to look. It is possible the spring loaded flap has jammed as they are flimsy little buggers! Good news is at least they are serviceable and the parts available.