The flywheels you see here belong to Brad Lackey, ex-world champion motocrosser from the 1970s and 1980s, and one of the most knowledgeable Harley owners you will find. A simple installation and a few hours in the saddle will tell you what a difference they make on your bike. If you don't like them, remove them and return them in good condition to Sun-Tech Innovations for a full refund. Sun-Tech knows its product is good, and that's why the company guarantees that it will perform. But the following information may suggest otherwise.
Balance is defined as a harmonious proportion of elements in a design.
When that harmonious proportion is disturbed, destructive vibrations are released-vibrations that mean premature engine failure. A 1200cc conversion piston with pin and rings weighs 495.5 grams. A stock 883cc pistons with pin and rings weighs 421 grams. That's a difference of 74.5 grams per cylinder. Another notable difference is that a Harley-Davidson stock 1200cc conversion pistons is 31 grams heavier than an aftermarket 1200cc conversion piston.