Hi! Maybe a dumb question, but I'm having a hard time finding concise info on this. I have an '02 883, and the CV carb has a overflow drain tube that routes out the bottom of the carb and to the front of the bike behind the oil filter to the ground. Is this drain tube necessary? Can I cap the drain plug? Or is the tube just there to let me know if/when my float is sticking/overflowing the carb? Not sure what the function of the tube is, or if it is 100% necessary. From what I can tell not all CV carbs have this overflow function.

Also, my gas tank has an overflow drain routed to the ground as well. Drain plug is on the RH side, and is routed down below the swingarm on the back of the motor. Is this overflow also 100% necessary?

Thanks!

 

Correct, not all versions of the Harley CV carbs have the drain/overflow tube. There is a screw on the bowl (backside-bottom) that opens the drain. (leave it closed) The extended tube was only there to prevent fuel from spilling onto the engine case in case of a stuck needle valve.

You can take the long plastic tube off without any issues - no need to cap it off.


I would leave that connected.

 

Awesome, thanks for clearing this up! I think I'll leave it connected or maybe re-route it so it's not so glaring up front.

Thanks!

 

the gas tank tube is a vent, not an overflow. You close plug that and you will not get gas to the carb, it’ll vapor lock, unless you have a vented cap.

My Buell blast blast does not have that hose you are referring to on the carb. The over flow on that cv carb is on the passenger rear seat side I believe. I’m not very familiar with cv carbs, but I believe the hose you are referring to is just a hose to drain the carb bowl. So yes, you could ditch it and cap it. Not even sure if it’s called vapor lock, but fuel will not flow.

but, fact check my reply before you go a/wall on your carb. I’m a mikuni guy, but would bet 77% that I maybe correct. I’m 4 beers deep into the lockdown

 

IF you cap off the overflow AND IF the float sticks, that fuel is going down the intake....

(assuming you forgot to close a manual fuel valve)

 

past the ring into the sump, then the oil pump will circulate gas through the engine. Doesn't seem like a good idea, but it will look better.

 

The reason some CV's have it and some don't is because of the petcock of the bike it came off of. If the bike has a manual petcock then it gets the overflow tube. If it has a vacuum operated petcock then it doesn't need one. I prefer having one just in case but I had a Pingel manual petcock. If you have a vacuum operated petcock then just pull the hose off, you're good.