I've been playing with my new toy, an Indian built 12/2. (Bharti Brand)
After polishing the lifter bowls, rods and threaded tips to the rods I noticed upon turning the fly wheel with the decompression levers in place that there seemed to be a slight sense of compression at TDC on both cylinders.
After a little poking around I noticed that the castings for the decompression stops were too long and the pistons were indeed hitting the valves forcing the flanges on the exhaust lifters to bend.
The fellow I bought my engine from mentioned that his had broke also on another engine but he wrote it off to poor craftsmanship. He made an exact duplicate and we discovered today that that was in fact the same problem that broke his original.
It's a problem I wouldn't expect but it may be worth looking for.
Regards
RF