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Dirt Bike Discussions By Brand
Yamaha MX & Off-Road Dirt Bikes
'01 YZ250 Cylinder Suction Pipe?
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[QUOTE="Solid State, post: 1186254, member: 22186"] Your power valves are actuated by the vertical movement of the actuator rod. That rod is pulled up and down from the rotational motion of the crank in the bottom end. The rod pulls on an arm tied to a rod in the cylinder causing that rod to rotate. This rotation in turn pulls the power valves in and out using an elaborate linkage system. You have three power valves - a main valve that opens first and then two side valves that begin opening when the main is opening fully. The side valves look like plugs or barrels and the main looks like a wide slide. The power valves actually change the exhaust area volume and the exhaust gas speed. In order for this system to work properly, there must be normal atmospheric pressure on the back side of the valve mechanism. That is what the rubber hose is for. It allows the valves to push back and not be restricted by a sealed air chamber. Some exhaust gases will pulse through this hose under normal operation. If your tube blows off, then there is either too much pressure getting past the valves or the tube is clogged. In either case, I would service the valves through disassembly, cleaning and replacing any worn parts. You should be aware that the main valve on your year 250 is prone to fracture over time. Good luck. [/QUOTE]
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Dirt Bike Discussions By Brand
Yamaha MX & Off-Road Dirt Bikes
'01 YZ250 Cylinder Suction Pipe?
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