1. Check the Gasoline Condition
   First check, the condition of the gasoline in the tank. If it is 9+ months old, it has probably gone bad. In order to make the determination, compare it with fresh gasoline for color, clarity, and smell. For clarity, it should be crystal clear with no haze, sediment, or precipitate. For color, it may have a slightly different hue, but it should still be light in color, usually straw yellow. For smell, the odor profile should be pretty similar, but don’t overdo it on smelling it—all varieties of gasoline contain many hazardous components, nearly all of which are quite volatile. If the gas still seems OK, skip the next section. If it has gone bad, read on.
2. Drain the Gasoline
   You will need to restore your fuel system by draining as much of the base gasoline as you can. If it is at all possible to remove the tank, do so and add a few ounces of B-12 Chemtool Fuel Treatment (part #0116) to it, and carefully swirl it around. Be very cautious with the B-12 if you’re fond of your paint because it can ruin most finishes. Drain the B-12/bad gas blend, repeat until clear, and reinstall the tank.
3. Add B-12 Chemtool Fuel Additive
   At this point, you should also use a top-quality fuel additive. We recommend adding B-12 Chemtool Total Fuel System Clean-Up (part #2616) at 1 oz/gal and topping off with fresh gasoline. This additive will thoroughly clean the fuel line, carburetor (internally and externally), intake valve(s), and combustion chamber. If your gas tank is fairly small, you should run the 2616 in back-to-back tanks.
4. Clean the Carburetor
   As far as the carburetor itself goes, the easiest way to clean that up is to remove the air filter and spray B-12 Chemtool Carburetor, Choke & Throttle Body Cleaner (parts #0113 or #0117) directly into it. Assuming that the carburetor hasn’t corroded internally—that can happen with aluminum carburetors that sit too long with ethanol-based gasoline like “E10” in them—then that should quickly help smooth out the idle and improve runability. You can, of course, start with this step, but doing so may only temporarily mask bigger issues.

Once you’ve completed this regimen, you can be confident that your fuel system is healthy again. However, if you plan on letting the motorcycle sit for extended periods of time again, you need to make sure that the gasoline is protected. Adding a fuel stabilizer to the gas tank such as our Total Fuel Stabilizer (parts #0408 or #0416) and topping it off with fresh fuel will accomplish this.

Best of luck with the bike!