Open Pipe Near Carbs

I'm doing some spring cleaning on the viffer (woot!), and I noticed this open pipe between the #1 and #3 carbs. What's supposed to go here? I believe my bike was de-snorkeled by the PO. Is this a remnant of that process? Should I plug it?


DSC05280.JPG

Looks like the crank case breather, should plug into the bottom of the air box to vent the pressure build up in the crankcase.

... or carb vent.

I couldn't recall seeing anything like that near my #1 and #3, and was about to pull my tank up and have a look until I noticed you are on a '96. The carbs are a bit different between the generations. We can surmise it is not a vacuum line due to the size. We can also infer that it is not a fuel line (you didn't mention the bike not running any longer or fuel pumping out on the floor at an alarming rate).
I would also guess it is a vent for the crankcase. It doesn't look to be part of the air injection system (PAIR), but it may be part of the evap canister. Can you run the engine and test the hole for air flow. If it sucks, I'd cap it (or run it to somewhere with an air filter). If it blows I'd leave it be.

It's definitely not a fuel line; the bike runs fine, apart from a very occasional midrange stumble that I haven't yet tracked down. I wish I'd read your post before I buttoned everything back up. I'll check it the next time I'm in there. I went in to replace the battery box front bit and ended up lubing the throttle/choke linkages, cleaning the air filter, & cleaning the exterior of the air box. You know how one thing leads to another.

blkrabit, Mar 6 2007, 06:08 AM& cleaning the exterior of the air box.

At the front of the airbox is a plastic air intake pipe/tube. Was yours covered in some fungi/mold looking substance as well? I thought that really weird.

Here are some images from the service manual that may help

[image: Image1.jpg]
[image: Image2.jpg]
[image: Image3.jpg]

So it goes into the secondary air filter...hmm. I wonder how important that bit is.

This is the float vent: do not plug it or put it in a way that air will be push in, or sucked out because you will have the wierdest carb problems you can imagine (by that I mean drivibility, nothing will be damaged).

Usually, you put a hose and route it somewhere neutral: no wind to push in or suck out the air. Like under the fuel tank.

What it does is when the gas in the carburator bowl is drwan into the engine, you need the air the remain neutral to compensate for the lower and filling of the bowl.

Hope that helped,

SG

St�phane, Mar 14 2007, 05:12 AMThis is the float vent: do not plug it or put it in a way that air will be push in, or sucked out because you will have the wierdest carb problems you can imagine (by that I mean drivibility, nothing will be damaged).

Usually, you put a hose and route it somewhere neutral: no wind to push in or suck out the air. Like under the fuel tank.

What it does is when the gas in the carburator bowl is drwan into the engine, you need the air the remain neutral to compensate for the lower and filling of the bowl.

Hope that helped,

SG

yep & yep, the first manual pic part number 7 is what the vent connects too & has a small filter pad inside to keep out grit. I would make sure that vent you have open at carbs be filtered if you do dirt roads from time to time or ride in allot of dust. Simple fix would be to clamp some panty hose (stocking mat) over carb mounted vent as a cheep filter fix (better would be to reinstall hose line to airbox mounted plastic fitting (part 7 first pic) if you still have part fitted.

Leaving as is wont do anything except let grit into carbs so cleaning intervals may have to be increased.

zRoYz, Mar 13 2007, 09:32 PM

St�phane, Mar 14 2007, 05:12 AMThis is the float vent: do not plug it or put it in a way that air will be push in, or sucked out because you will have the wierdest carb problems you can imagine (by that I mean drivibility, nothing will be damaged).

Usually, you put a hose and route it somewhere neutral: no wind to push in or suck out the air. Like under the fuel tank.

What it does is when the gas in the carburator bowl is drwan into the engine, you need the air the remain neutral to compensate for the lower and filling of the bowl.

Hope that helped,

SG

yep & yep, the first manual pic part number 7 is what the vent connects too & has a small filter pad inside to keep out grit. I would make sure that vent you have open at carbs be filtered if you do dirt roads from time to time or ride in allot of dust. Simple fix would be to clamp some panty hose (stocking mat) over carb mounted vent as a cheep filter fix (better would be to reinstall hose line to airbox mounted plastic fitting (part 7 first pic) if you still have part fitted.

Leaving as is wont do anything except let grit into carbs so cleaning intervals may have to be increased.

That's what I was considering doing: placing a small hose on it with some sort of filter on the end to keep crud out. I don't have the original filter bit that came on the bike.