Jims "On-Bike" Valve Spring Compressor Tool For HarleyDeveloped by JIMS, this patent-pending valve spring compressor system offers a time-efficient solution for mechanics working on Milwaukee Eight engines. The product allows for expedient valve seal replacements and spring changes while the cylinder head remains mounted on the motor, bypassing the need to fully dismantle the engine. This ingenuity not only streamlines the process but also curtails unnecessary expenditure of time and resources, making it an essential tool for both routine maintenance and performance upgrades.Features: This patent pending tool dramatically saves time for any technician working on Milwaukee-Eight performance upgrades or service work Simply remove the rocker box covers and rocker arms, and install this unique compressor on the rocker arm shaft Once the cylinder is filled with compressed air, the technician can easily rotate the tool and compress the top collar of the valve spring exposing the keepers to remove the top collar, valve spring, and seal Made in the USA