Mystery pipe on Right Hand inlet?

[redshiftrotary]

Hello to all you experts and I apologise in advance for what is maybe a silly question.
Air cooled IP2, not long in my possession, checking and adjusting this and that I find there is a clear plastic pipe connected to the Right Hand Inlet pipe 50-0272. It seems as if it comes off one spigot, round the back of the Inlet Pipe and back into the other spigot, all about midway down on the R.H. side. Not shown in my parts book, not connected to anything other than itself (via the inlet pipe) and not fitted to the L.H. side. Any ideas?

[wust588]

Hello there.

As far as I can remember, the very early air - cooled prototypes had carb inlet pipes with 2 vacuum stubs on the RH side
and 1 on the LH. The RH stubs were for scavenging oil from the main bearings, which was discontinued on later bikes.

The LH carb pipe stub is the vacuum for the frame oil scavenge. A lot of the prototype bits have been floating around for years,
and are used blanked off like yours.

John.

[redshiftrotary]

Ahaa, thank you John, a comprehensive reply.
It's always a worry with a 'new' bike as to what the previous owner has done and therefore should that pipe be connected to something else etc. etc.
Now all is clear and understood. Regards, John.