Twin Mukini Carbs vent lines

I have installed twin Mukuni Carbs on my 750 commando I am ready to fire her up I have a question regarding the vent tubes that are on these carbs There are 3 on each one and I have them joined together pointed downwards. What are these tubes for and is there a danger of gas coming out of them. Should they be joined together in some way? Any info on Mukuni's would be helpful
Thx
Drummer99

They are just vent tubes as far as I know, I wouldn't join them together if I were you
One of the tubes on each carb is an overflow , you won't want that joined to another one
I'm assuming you have mikuni VMs ?
If they are I have heard they are very difficult to set up and I know one person that gave up after many tries to get a pair of VMs working on an 850 commando
But after saying that I have 3 vms on my trident and it runs superbly

It's been a while since I did a lot of Mikuni work but I recall two vents and a vacuum fitting but probably different Miks had different configurations. There is a bowl vent and and overflow vent. The overflow vent could have fuel if the floats are set to high/not floating. The bowl vent would not normally be expected to have fuel. If the 3rd fitting is, in fact vacuum, it needs to be plugged unless it is connected to a vacuum-operated petcock.

An easy way to avoid the confusion is to install a new set of Amal Premiers!

Sorry, couldn't resist...

Hi Drummer , one of my commando (920) have one one pair of vm34 , they run perfectly, and were jetted in 1997 by Sudco , and let those vent lines as they were , not joined !

marinatlas said:

Hi Drummer , one of my commando (920) have one one pair of vm34 , they run perfectly, and were jetted in 1997 by Sudco , and let those vent lines as they were , not joined !

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That's great info, would you be able to post the spec of your carbs and engine /exhaust system and air filters please

Don’t join the vents and overflows together.
Many Mik’s have short little bowl vent lines, and on the bowl overflow, a longer hose is run down to the lower frame tube level, in the unlikely event an overflow condition occurs.

baz said:

That's great info, would you be able to post the spec of your carbs and engine /exhaust system and air filters please

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Hi, the 920 is 4s, RH4 by Pete Lovel small valves, uni filter socks, 260 main, 159Po,6DH3,35 pilot, 2.5 slides, std peashooter, Boyer red .......run OK, as a road bike........

I just pulled the pink plastic tubes off and mounted the Mik , all good , UNI 2 layer sock here too ....
Craig