From the early days of bicycling up to the mid 1950's, bicycles used sprockets with every other tooth missing. They were made that way at the factory, and were called skiptooth. I suppose its possible that the sprockets on your homemade quad were not originally skiptooth and instead were ground off, but fwiw it wouldn't have effected the gear ratios at all. If any of the chains are still intact, you can tell if they were skiptooth chains by looking at the rollers. Every other roller would be closer together, and every other would be farther apart. The teeth can only catch on the ones that are farther apart, if I'm not mistaken. The reason that skiptooth is no longer an industry standard is because the asymmetrical roller spacing placed uneven wear on the rollers and caused worse wear on the sprockets than the now standard symmetrical roller spacing.