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The bike was running fine, but was making a squeak squeak squeak noise as it ran. I searched everywhere for the source of this noise, and finally found it. It was the reed valves. There is a short rubber hose which is MOLDED onto each reed valve assembly, and both of them had deteriorated to the point where they had cracked and split. The noise was coming from a pulsed vacuum leak at each reed valve.
The system works like this. On each side of the engine, back in behind the fuel injectors, and attached to the bottom of the air plenum (what the air filter housing attaches to) there is a reed valve assembly. Each assembly actually contains 2 reed valves, one for each cylinder on that side of the engine. Each reed valve assembly has 3 connections. 2 of them connect to vacuum ports on the 2 cylinders on the side the reed valve is on. The stock hoses are red. Then there is a third connection, on the back of the reed valve assembly. This is where my problem is. It is the short piece of rubber hose that is glued to the reed valve assembly. It deteriorated and broke. I removed it from one of the reed valve assemblies, including all the glued on rubber, with a wire brush wheel on a Dremel. There is not enough of a nipple sticking out to clamp a regular hose onto.
Ok, what this little short hose does, is provide a connection point for a white plastic elbow on the right side reed valve, and a white plastic "T" fitting on the left side reed valve. A rubber hose connects to the white plastic elbow (which fits into the glued on rubber hose) on the right side of the bike, then runs around the front of the engine, where it connects to a "T" fitting on the left side. Other than the "T" fitting, the left side reed valve assembly and connections are exactly the same as the right side. The let side has a "T" fitting instead of an elbow, because TWO rubber hoses connect to it. One from the "elbow" on the right side reed valve, which connects to the left side reed valve, then another hose, which connects to the AIR valve. So, the entire reed valve system, with 2 reed valve assemblies, hoses and fittings that connect the 2 reed valves together, and 4 hoses which connect each reed valve assembly to the vacuum ports of the 2 cylinders on each side, all wind up at a single connection at the other end. The AIR valve.
Now, the AIR valve has several hoses and a wire connected to it. ONLY ONE of the hoses is a vacuum hose connected to the whole reed valve setup. Another hose connects fron the AIR valve to the air filter housing, from what I can tell, just a source of clean air. There are also 2 coolant hoses on the AIR valve, which go back to the radiator/water pump area. one is supply, one is return. I have no idea what they do. There is no temperature sensor on the AIR valve. The wire that I thought was a sensor turns out to be nothing but a heating element.
So since this entire bowl of spaghetti has no sensors of any kind, sends no signals to the ECM, just what exactly does it do, and how does it do it? What do the reed valves have to do with anything, and just what does the vacuum actually control when it finally reaches the AIR valve? And why can't I just remove all of it, plug the vacuum ports at each cylinder, and have the bike run? That would solve my whole problem, and I cannot figure out any reason why it wouldn't work.
BUT. before I took everything apart, I did just that. I removed all 4 red hoses, plugged the vacuum ports, then removed and plugged the vacuum hose at the AIR valve. The engine would start with wide open throttle, but died at about 3000 rpm, suddenly, just like you had cut the ignition off. There has got to be something to this system that I am not seeing.
Again, would appreciate any and all information about it. Jerry.