Crankcase breather

Hello Access

After installing cNw breather and having had my oil tank modified by cNw (

Colorado Norton Works Norton Commando modifications by Colorado Norton Works Custom Norton Motorcycles

Norton Commando modifications by colorado norton works

coloradonortonworks.net

)
Looking at the oil line routing, it appears that the crankcase is now a closed loop system.
How does the crankcase vent to atmosphere so as not to build pressure? What am I missing?

Thanks

That is normal and the reason for the reed valve to lower the internal pressure, a partial vacuum being ideal.

The oil tank still has its vent, the crankcase breather hose going to the oil tank.

I missed the vent line at the fill spigot. Sorry for the dumb a$$ question.
Thanks

The vent hose is off the central bulge, the case breather to the fill neck. (IIRC)

Time Warp said:

The vent hose is off the central bulge, the case breather to the fill neck. (IIRC)

Click to expand...

I stand corrected.............thanks again

You would have spotted it come time to fit the tank or hoses.

Most likely there would be some oil loss if the vent was off the filler neck but with oil being able to get to the filter unit the stock system is not perfect anyway.

That might come back to, where should the tank vent go to.
The air filter unit with possible detonation or some other chore related catch can that needs to be vented.