Trail Tech flywheels replace the stock flywheel.  Trail Tech flywheels offer improved balance and ideal weight choices.  30 Minute Install: Open Side Case Remove Stock Flywheel Install Trail Tech Flywheel Close Side Case A flywheel puller screws to the center of the flywheel to protect the crank during flywheel removal. ALWAYS USE THE CORRECT FLYWHEEL PULLER. (Puller and side case gasket not included in flywheel kits.)  READ THE INCLUDED MODEL-SPECIFIC INSTRUCTIONS! Please contact us if you think any notes need to be added to our instructions, thanks. Trail Tech Flywheels are CNC machined from hardened chromoly steel. Each flywheel is individually balanced.   Use an air ratchet for easy removal (use the correct flywheel puller.) Use hand tools to tighten (use OEM torque specifications.) Heavy Weight: Heavy weight flywheels reduce stalling, improve traction, reduce the need for clutching, and make the bike easier to start. Adding weight increases inertia, which reduces the bike's tendency to stall at low speeds. Top speed is not affected - the heavy flywheel smooths power delivery. The machine will hook up better in soft terrain, and pull stronger. Riding with a heavier flywheel will reduce arm pump and fatigue. Reduced Weight: Reduced weight flywheels add snap to acceleration. Subtracting weight allows the engine to rev faster, which provides a distinct advantage when getting up to full speed quickly is required. Sand, dune and MX riders will generally choose a light weight flywheel.