Take your left tank cover off, and look at your gear position switches. Hose them out with contact cleaner and see if that helps. The reverse sputtering is because one of the sensors doesn't show the bike is in reverse. It's a built in safety measure.
When you put it in reverse, the R has to show up AND the red reverse light must be on. If both are not present you get the sputtering.
Next time you put it in Reverse, wiggle the shifter around and see if you can get both the R and the light, and see if it sputters.
When you put it in reverse, the R has to show up AND the red reverse light must be on. If both are not present you get the sputtering.
Next time you put it in Reverse, wiggle the shifter around and see if you can get both the R and the light, and see if it sputters.
