1970-1979 Ski-Doo Snowmobiles Service Manual, Page 37Get this manual
30 Check that timing mark on the magneto ring aligns with the center mark on the crankcase as shown in Figure 37If timing marks are incorrect, remark magneto ringRepeat for the other piston5Check air gap between the magneto ring and each trigger coil as shown in Figure 38If air gap is incorrect, magneto ring will have to be removed and the armature plate repositioned (refer to Flywheel and Magneto Removal in Chapter Four)Air gap for each trigger coil should be 0.040-0.063 in(l-1.6mm)6Connect an external powered timing light to magneto side spark plug wireUse an external battery if using DC powered timing light7Start engine and run up to 6,000 rpmTiming mark on magneto ring should align as shown in Figure 37If marks do not align, perform the following: aLoosen screw securing trigger coil bracket and adjust bracket up or down slightly until timing is correct (Figure 39)Repeat for the other cylinder