Drives is Ok, It does stretch but it's has a fair price. I just put EK 420 cycle chain on the red scrambler racer and although it has a small amount of hours lugging my big butt around it has not required any adjustment. It was not cheap. If you want to learn something about chain and sprockets or if you want to purchase some titanium chain check out Sidewinder chain. Motorcycle Chains | Motorcycle Chain and ATV Chain | Worlds Finest
You could probably lighten up your racers considerably by going to titanium sprockets and chain.