Topic: Carb vent tubes really needed?

[xluckx]

Hey all,
Just rebuilt my carbs and forgot to put the vent tubes back on. I must say I really like how much more simpler the motor/ carb look with out the vent tubes coming from the carb. So four come from the bottom of the bowls and two up top. So the question is do I really need to use them?

Its for a 72 Cb500

Thanks guys, I really appreciate your help and this site!
Steve

[Dimitri13]

Well if you don't want gas dripping on the engine case I'd definitely keep the overflow tubes. Not sure about the vent tubes though. I always thought about leaving them off because they were always so hard to get on after the carbs were on (and I'd always forget to put them on beforehand).

[Really?]

Personally I would keep them hoses on.  I have had leaky carbs before.  I am glad the fuel was routed more to the ground.

[Ernest T]

The vent tubes keep water out of the carbs--they are not overflow tubes.  They connect to two vents that point up between carb 2 and 3, at least on the CB400F anyway. If you park it in the garage and don't ride in the rain you can ditch them.

[Stev-o]

I don't have the overflow tubes on my K4 or my 550K. The K4 has never leaked but the 550 left carb will leak if petcock is left on and bike on sidestand, but no biggie.
You do risk a possible fire from leaking gas leaking on a hot engine and most likely why Honda installed them.

It could happen.

[Tews19]

I was wondering the same thing. I have them off of both my 550's right now. PLus I need new ones. Any idea where i can order those?

[crazypj]

As previously stated, they are needed if you ride in the rain.
I would re-fit all of them but you really need the top ones (you never know when you'll get caught out)
Yamaha found out the hard way, having them too short allows water to get sucked up lines into float bowl as the air pulses while engine is running