The SKT articles I read about setting up a 250 MX had a few hints about strengthening the 74-75 MX frame. Does the Jackpiner frame need strengthening in any specific areas? Thanks!
The "Factory Novice"
If you are running it in Vintage and not in the laid down position you are okay. Unless you ride like Kent Knudson's riders rode them. I am not sure of how hard you ride but I have never broken one. I don't ride like those guys, though. If you feel the need gusset work on the steering head is the place. I think with an average to better than average racer they are fine as long as the head stays adjusted and you don't let any play develop. If you are a total wailer then go for gussets. If you are worried about the old frame I have an NOS 175 frame I have been saving that has never been stressed. It will need paint but has never seen torque.
Larry P