bike has 65,000 miles on it, yesterday it decided to start running on one cyclinder, yes I will replace the plugs tonight. anybody has any thoughts or idea on this
What year? I'm going to guess water sitting in the coil. Probably #2 coil in cyl1 or #3 coil on cyl2. You will see a difference in the coil if it's water damage. They will be white on the bottom, the rest (normal) will be clean and black. Maybe dropped one, or both coils. I've seen it before. Most of the time it's on the 12 / 13.
Plugs won't drop a cylinder all at once.
+1 to plugs and coils. Bet you find a rusty plug and one coil looking cruddy. Pull the plugs and one will probably be different.
btw - Your local auto parts store probably won't have the plugs on hand.
If it turns out it's not a plugs or coil issue there is an off chance it could be the in tank fuel filter. Bike (2012) started up in the morning on one cylinder. After a bit of warm up an coaxing it would reluctantly run on both if the rpm was kept up. Fuel filter had quite a bit of water, and some dirt contamination.
And the sound a 1200 cc twin running on one cylinder isn't pleasant to listen to. ???
Inspect the coil's interconnect for corrosion. I spray silicone on it before installing them back. If there r corrosion, maybe scotch brite it with the help of a small screwdriver.