2015 Copperhead 18HP Vanguard V Twin The 18 HP is the smallest V-Twin copperhead makes. For being small it will still push a 1540 with 2 men and gear 22 to 25 mph. One big difference between the single cylinder engines and the V-Twin is the noise and vibration. With the V-Twin, you'll get sewing machine smooth operation that's great on those long hauls. The 18 HP comes standard with electric start, recoil back-up starting, remote fuel, upgraded 20 amp charging system, heavy duty starter solenoid and 5 feet of battery cable.