if the coil is green its the low limiter , 9600 to 10000 rpms and sucks to run the saw, black coils also vary in rpms with some in the lower 11,000 to 12000 rpms . Donot put a unlimited coil in it as you will most likely break the rod as that is a weak spot on the 3120 . If you need to put a black coil in it but you will need to change the flywheel to the one that works with the black coil , green coil flywheel timed a lot different.