I do backcuts on the gears, but only if they are in good shape to start with and have minimum wear. I change the angle on the drive side of the dog to help suck the gear in place on the shift, it helps to save the life of the gears and you don't miss as many shifts. This was originally started to help save the 73/74 CR250's, I have since done some other engines. The 79 CR250 is a pretty good gearbox, your best bet and the cheapest is to just replace the gears, and if any shift forks have the chrome worn off they should be replaced to. The Honda gears are only case hardened, somewhere around .030 - .040 thick, once it breaks through that case hardening the gear goes really fast.
