6S5-12121-00-00 Exhaust Valve for Yamaha AR 190 1800 2012-2023

Exhaust Valve for Yamaha

This exhaust valve, OEM cross-reference 6S5-12121-00-00, controls exhaust gas flow out of the cylinder head on Yamaha 1800 marine engines.

Overview

This exhaust valve is a direct-fit replacement for the Yamaha 1800 engine used in AR 190 and similar sport boat models. The valve seals combustion gases during the power stroke and opens at the right moment to release exhaust, keeping cylinder pressure and engine timing in balance. It suits boat owners and marine mechanics doing top-end service on a Yamaha 1800 engine.

Built For Performance

• OEM cross-reference 6S5-12121-00-00 for accurate matching
• Valve head and stem sized for the Yamaha 1800 cylinder head
• Heat-resistant alloy construction suited to continuous marine exhaust temperatures
• Precision-ground stem surface for smooth guide travel
• Faced valve head for a consistent seal against the seat

Fits These Machines

• for Yamaha AR 190 (2012-2023)
• for Yamaha 1800 engine applications

On-The-Job Use

• Top-end rebuilds on Yamaha 1800 marine engines
• Cylinder head service after a burnt or leaking valve
• Routine valve clearance and compression maintenance
• Boat yard repair work on AR 190 sport boats

Specs At A Glance

Good To Know

Q: How many exhaust valves does a Yamaha 1800 engine need? A: The 1800 four-stroke engine uses one exhaust valve per cylinder, so order the quantity your head service requires. Confirm your engine configuration before purchase.

Q: Should exhaust valves be replaced as a set? A: Many mechanics replace all valves in a serviced head at once to keep wear even across cylinders. Follow your service manual for the correct procedure.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.