...And before you suggest removing the canister from the bike, I've already done so...and that's where the question comes in.
Years ago I removed the canister from my '07 R1200GS, tossed it in a box, and forgot about it. I don't even have that bike anymore (moved on to a '12 that was already de-canisterised), but I still have its canister and now I have a use for it.
Not long ago I purchased an old British sports car that has a tank-venting setup that basically just vents to the air through a large hose, causing evaporative losses of fuel and nasty fuel-smell in and around the car. My thought is to re-purpose the old GS canister in this car, and it looks like it should work except for one thing: there's a third connection on the canister and I don't know what it does. It's on the opposite end to the other two connections, and it's a larger diameter than the other two. I can't for the life of me remember what it was connected to on the bike. Does this third connection need to be connected to something for the canister to function properly? If so, is it anything special that would preclude using this canister and therefore require me to buy another type instead?