I got my 2011 630 used so some mods have been done already there looks like there's a vacuum tube on the left side of my head that just is plugged up in my manual the tube looks like it goes somewhere could someone please tell me what this could be and if it's OK to way it is Thanks ed
It was a source of vacuum for the evaporative emissions canister that hung off the right side of the bike like a tumor. Should be capped off if you don't have the canister. ETA: the thing on the right
It's an air injection port,,either for fuel vapor or exhaust flow coming out of the head...Plug it with a bolt screwed into the intake(like the pic you showed)and your good to go....
How would you expect fuel vapors to make it into the combustion chamber except through that line? The canister is a carbon EVAP canister with 3 connections. One to the tank vent, one to the head, as shown, that is a port into the intake passage (vacuum), and the 3rd is to the ground to drain liquids. There is a much smaller burp valve (diaphragm check valve) in the tank vent line. Notice where the plugged nipple is, it's right next to the throttle body and opens into the intake port. No way for any kind of positive pressure to be present there short of forced induction. And the "little round part" weighs almost two pounds and is 4 inches in diameter. More than just a gulp valve.
You may understand how a fuel system works, but you don't seem to understand how the emissions systems on a Husqvarna 630 work at all... There is no manually or electrically operated "gulp valve" as you describe it, and you seem to think that the canister is getting positive pressure from the engine, yet somehow delivers fuel vapors TO the engine, all through the same hose. As someone with some wrench turning experience and a mechanical engineering degree, I'd say I have a pretty firm grasp on how this system operates. Here is how it works, if you don't believe me, well, it's out of my hands. -The tank vents to the canister through the check valve (some call it a burp valve, it is "burping" the tank, and it sounds like a frog when it's venting). -The engine draws the vapors in from the canister through the nipple shown above. It does not provide exhaust, it does not provide air pressure. It is vacuum, pulled directly out of the intake port between the throttle and intake valves. THAT IS WHAT VACUUM IS. -The hose from the canister to the ground vents excess vapors and liquids from the fuel tank.
Not sure if you realize, but the small one-way valve / check valve / burp valve in the tank vent line is a diaphragm type, and is not a zero-cracking-pressure valve. It requires the tank to build a certain amount of pressure before it releases a portion of the built-up vapor. That's why some call it a "burp" valve and not just a one-way valve. This burp valve doesn't let air into the tank, the vapor pressure from the fuel in the tank prevents it from dropping below atmospheric pressure. The one-way function of the valve is to RELEASE the vapor FROM the tank. This is why some people have had trouble in extremely cold climates with gravity-fed carb bikes, as the fuel is consumed at a higher rate than it vaporizes in the tank, so it creates a low pressure in the tank, preventing fuel from draining freely to the carburetor bowl.
