Owners of 2003 Yamaha RX-1s may experience poor performance or ignition misfiring caused by a poor connection between the coil caps and spark plug terminals. The original spring clips used inside the plug caps could cause the coils to not be held securely on the spark plug. This can cause the coil to “notch” the threaded end of the spark plugs, leading to a poor connection and resulting in misfiring.
If you witness deformation of the spark plug ends, or find the coils to be loose fitting on the spark plugs, you can upgrade to the newer style updated ignition coil caps that have a revised style spring clip. Order Yamaha part #8FA-82310-01-00.