What's this pipe on the carb ?

[dwhitehouse]

What is this open pipe for and should be blanked off or connected to something ?

There are two of em. One on No4 carb and one on No2.

I've only had the bike 12 years I guess I should know by now.

[warren3200gt]

Vent, to let air escape from the bowls as the fill with fuel. Should be two. One between 1&2 and one between 3&4.
Should have a pipe back to airbox ( well on 650's anyway)

[zed1015]

Those are float bowl vents and must be left open to atmosphere.
Ideally they should have tubes on them which usually run over the air box if fitted or some short ones hanging down between the carbs just to prevent easy ingress of muck.

[dwhitehouse]

Ah, obvious now you say it.

Thanks all.

[Gray17]

I also wondered this when i removed my carbs for rebuild, there was no pipe on mine either. So they should either have pipe to the air box or just a small bit of pipe to prevent dirt entry. As you say sounds obvious as fuel rises needs to vent or you'll pressurise it. This is problem with old bikes thats been played around with over the years, theres bits missing or removed thay you'd never know about.

[zed1015]

Also if you have one of those brass stubs on number 3 carb it's a take off for a vacuum fuel tap and must be capped off if not in use otherwise that cylinder will run very weak and you will have issues maintaining a steady idle.

[Gray17]

Thanks i will check, def useful to know, again if youve just bought the bike and never owned from new like me you'd be none the wiser.
Thats whats so great about Forums they are such a wealth of amassed knowledge! Whatever did we do before the internet???