You have several options for cleaning carbon buildup off the pistons and rings. If the rings are sticking, consider Berryman B-12 Chemtool Fuel System Cleaner (part #0116), which is very effective at combustion chamber cleaning if want to perform a cylinder soak. That is accomplished by pulling the plugs, putting 0116 in each cylinder, letting the product dissolve the carbon, and then removing the mixture from each cylinder. You can also buy this product in a 1-gallon size (part #0101). Alternatively, Berryman B-12 Chemtool Total Combustion Cleaning Kit (part #2610) contains high-performance detergents specifically designed to thoroughly clean intake valves and combustion chambers by way of vacuum induction via either the PVC valve or the brake booster. This product is also available as “Step 2” in our Professional 3-Step Fuel System Maintenance Kit (part #2630). If you want a detergent-based product you can just pour into your gas tank, then try Berryman B-12 Chemtool Total Fuel System Clean-Up (part #2616). This additive will clean the fuel pump, fuel injectors, intake valves, and combustion chambers. Good luck!