YAMAHA BANSHEE 350 Fouling One Plug Constantly
| CONF | DIAGNOSIS | ACTION |
|---|---|---|
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91%
CONF
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Carburetor Float Needle and Seat Kit
The float needle and seat regulate the fuel height within the carburetor bowl. If the Viton tip or the seat orifice is degraded, buoyancy fails to seal the inlet, allowing fuel to rise into the emulsion tube via hydrostatic pressure even at idle. This results in a localized rich condition that fouls the spark plug of only the affected cylinder.
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|
|
5%
CONF
|
Right Side Crankshaft Oil Seal
On the 'wet' side of the engine (clutch side), the crank seal separates the combustion crankcase from the transmission oil. If the elastomer lip fails, the vacuum created during the piston's upstroke draws gear oil into the crankcase. This oil does not burn cleanly at the standard 2-stroke combustion temperature, leading to heavy carbon deposits and 'wet fouling' on the right-side plug.
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|
|
4%
CONF
|
Carbon Fiber Reed Petals
The reed valve acts as a one-way check valve for the intake charge. If a petal is chipped, frayed, or lacks sufficient tension (fatigue), it allows 'spit-back' of the fuel-air mixture into the intake tract. This disrupts the pressure waves and leads to poor atomization and pooling, which causes the plug to foul during low-RPM operation or idling.
SKU: 3GG-13613-00-00
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DIY Repair Guide
Watch exactly how to replace the Carburetor Float Needle and Seat Kit.
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