There are 3 hoses on the carbon canister, two hoses are about 3/8" ID. and 1 is about 1/4" dia.
The 1/4" hose(has tip of pencil just behind it) is the one we are talking about.
When the bike is started, a vacuum is applied to the 1/4" hose, which opens the vent valve on the CC.
If this hose is disconnected, you have a vacuum leak somewhere and this surely will cause a off-idle stumble.
Just for info: The upper center- left 3/8" hose goes to the fuel tank tip-over valve. The 3/8" hose to the right wraps around the front of the CC and connects to the purge valve, which is mounted between the cylinder block and the front of the CC.
I would think Champ's '07 is the same as the later Sprints, but you can use "search" for "vacuum line diagram" and look at every post.
Last edited by Bruce C; 01-29-2012 at 11:56 AM.