Hey guys, I am trying to help my 13 year old brother out with a go-kart/dune buggy thing and I am not sure what I should use. The plan is a buggy that he can take to Pismo and cruise around the dunes in and be able to run with the "big guys". We originally planned for a little motor so he can run the beach and has manifested into much more. We had been looking at using the engine and trans from a 1980 RM80 but the motor is frozen solid. A call to a friend who has a motorcycle grave yard has this project looking at possibly using even a 450cc street bike motor. I'll take what I can get but I prefer no more than a 200cc. When this started as a lawn mower powered car we planned on 1"x.120" welded seam tubing but if we go to the 450 or even the 200 I am thinking we better step it to DOM, what do you guys think? Could we maybe get away with welded seam if we go with a bigger size or would it be better to stay at a smaller size with DOM? I know DOM is better but we are trying to do this on the cheap and I want it to be safe as well. Also what size tubing should we go with? Please help me out guys, thanks in advance!