Many people spend a lot of time and energy developing products to control the air on top of the pistons to increase horsepower, but what about the air under the piston. The KrankVent controls that air. Dyno tests have shown a 2 to 5% increase in useable rear wheel horsepower. Will prevent the engine from blowing rocker box gaskets and even cylinder base gaskets.
Comes complete with hose clamps and detailed fitting and maintenance instructions. Fits all Big Twin models up to 1992 and Sportster models up to 1990.