O.S. 21XZ-B Off-Road Race Engine
The 21XZ-B Version II delivers ideal performance at a reasonable price. It continues to exceed the expectations of even pro racers, delivering power comparable to the Speed Spec II at a lower price. Upgrades include a lightened cylinder head, improved cooling and a brand new 21J carb for easy tuning. If you're looking for incredible throttle response and the power to conquer off-road, you've found it in the 21XZ-B Version II.