This is the New O.S. SPEED B21 ADAM DRAKE 4 engine.
Features:
Based on OSB21 AD4 Cooling-head with extra fin for better cooling. AD4 specific cylinder design for more torque. AD4 DLC coated crankshaft with new modified inner diameter for better low and mid range power. Inner head with silicon O ring for reducing vibration and preventing dust AD specific blue restrictors. Rear-cover with thrust plate reduces friction against the connecting rod to extend its life. Long stroke 16.8mm engine Ceramic Main-Bearing Specifications:
