FAQ
The original oil rings were 3/32" thin. We've not found a manufacturer that can produce a 3/32" thick oil ring. However, we have plenty of 1/8" thick rings in stock, and most manufacturers can make a 1/8" oil ring. The solution is to machine the oil groove in the piston to match the oil ring, leaving a 0.0005-0.001" clearance for the ring.
To machine the groove, a 6-jaw chuck on a lathe can hold the piston steady. Soft jaws are preferable.
Indian switched to 14-1/2° gears to reduce wear and quiet the cam chest. Originally, all 14-1/2° gears were cad plated, making them easy to distinguish between the 20° gears. But, my experience is that all the cad plating in used bikes has worn off. So what do we do? A 1/16" drill bit is a handy tool for identifying which pitch angle you have. Lay the drill bit between two teeth. If the bit is "snug," then the gear is a 20° pitch. If the bit is "loose," meaning you can wriggle the bit between the teeth a fair amount, then the gear is the later 14-1/2°. Note that ALL generator driver gears (e.g., the fiber and, later, steel gear) remained 20° and only the idler gear was changed to 14-1/2°.
Of all the gears in the cam chest, the pinion gear is the hardest to discern between the two. The drill bit on a 14-1/2° gear will be "loose," and I mean that you can wriggle the bit about 15° back and forth between teeth, versus only 2° back and forth on a 20° gear.
If the push rods and push rod tubes are adjusted on a hot engine, shrinkage of the aluminum case, cylinders, and heads will cause the clearances to zero and "jack" the rocker boxes up. The result is the rocker boxes may break off, usually on the inlet manifold side where there is a high stress point in the machining. To avoid this, always adjust clearances on a cold engine.