Timing kit for inspection and adjustment of ignition timing; gauge face size 1 1/2". Comes with adapter for air-cooled 2 strokes. Although this is an excellent gauge, we do not recommend it for the RD250/350/400/R5/DS7 as there isn't enough clearance to use the gauge with the engine installed in the frame. For the RD250/350/400/R5/DS7 or any bike with minimal clearance between the frame and spark plug, we recommend the Economy Cycle Dial Gauge made specifically for RD and Yamaha twins, which can be found here
Economy Cycle Dial Gauge