Crankcase Lap Tool Part 978411

JIM’S, crankcase lap tool

Details

Used to lap pinion bearing race in the right crankcase. Removes more material in less time but with greater accuracy than a conventional lap. The JIM’S case lap is guided on both sides of the pinion bearing race. This additional support on the cam gear side of the bearing race is achieved by means of a bolt on the base plate that precisely locates a drill bushing in which the lap turns. This base plate is located on the same engine case pins as the cam cover. The positioning of this drill bushing is held within .0002″ to the engine case pins and within .0002″ of the case centreline. Now, instead of guiding only from the left side with Timken bearings, which are a floating fit, the JIM’S case lap uses a special ground bearing sleeve to hold the left side of the lapping shaft without movement. Both ends of the lap are supported precisely in the same centreline as the flywheel assembly. With this extreme rigid arrangement it is possible to power the lap with a low speed drill motor without fear of chatter in the lapped bearing race. The JIM’S lap can still be powered by the conventional hand crank when desired. It is recommended to use JIM’S 978341 (snap ring installer & remover tool), especially on 90-99 crankcases.Note: See 978412 vor the replacement 1-3/4″ O.D. lap head

Fitment

58-99 Big Twin crankcases (excl. Twin Cam) Code: Specifications

Part Numbers