I don't have a dog in this hunt, altho I have been part and parcel of several stock motor rule racing classes, and in a perfect world, it can be made to sound like it would be less expensive to run in, but this world is far from perfect, and the only man I know of, able to run a "stock" class motor, was a guy in Illinois, you may have run across his operation, but he made it work, now I realize this would be impossible in almost any other form of racing, but he owned the track, and ran it with his wife and kids, and they used "stock" motors. The deal was, when you went there to race, you paid your money, and you drew a chit, with a number on it, you took it to the next station, and gave it to the person behind the counter, who went to the motor room, put that chit on a nail, and pulled the engine off the shelf and that was your motor for the night, it was already to go, just add fuel, and mount it to your kart, race it, and turn it back in at the end of the racing, then thru the week, his sons would pull the maintance on the motors, and randomly put them back on the shelves, so no one ever got the same engine twice, and it worked very well. like I say, this would not work in this type of racing, but that is the one fool proof way to keep engines stock, me, I'd probably ck one by a draw, and just ck bore and stroke, or cc it, and not make a big deal out of it, most of the bad cheaters are usually poor drivers, and run in the back anyway, so if you do a random draw, you'll eventually catch the one's that have trouble with the "stock" rule. Just my 2 cents worth. Bob