1984 YTM 175 Carb Question

[Just-Tri-It]

I have a 1983 or 84 YTM 175. I premix the fuel as the oil tank was previously removed. I noticed that the vent tube which come out of the back bottom of the carb bowl is not vented to the crankcase cover next to the right rear wheel but hangs loose. When I hooked it up it filled the tube with gas and I had to take out the 3 screws to drain the casing. Why did it fill up with gas and is it important to have it hooked up there? Could I hook it up elsewhere. One gentleman said he thought it effected the timing if it was unhooked. I know it doesn't need to be filling with gas but don't know its original purpose.
Thanks for any imput.
I hope this is the right section to place this question.
sheeptender

[Vealmonkey]

The drain tube coming off the back of the carb float bowl is suppose to just hang loose and drain any overflowing fuel away from any hot engine parts. The overflow tube should hang about even with the bottom part of the engine case or slightly lower. The plastic casing you are talking about with the 3 screws is supposed to be hooked to a drain line coming off the bottom of the air filter box. Don't hook the carb drain to that.

[Just-Tri-It]

I dont think that is correct. The manual diagram shows the two tubes hooked up to the cover piece on the side of the casing with the 3 screws. It also says if the tube fills with gas to loosen the 3 screws and drain the gas out of the casing. The second tube that is hooked up is larger and goes back up under the gas tank into the hollow tubing. I have seen them hang loose and just about all the little hook ups for the tubing on other bikes are broken off so you cant hook up the hose. The cover where the 2 tubes hook up is like a small triangle with two small smoke stacks on top that you hook the tubes to. One is called the 'air bleed pipe' and the other is called the 'over flow pipe.' I dont think it goes to the airbox but I could be wrong. Thanks for the info.