dyno tested the 77cc piaggio kit and very pleased with results
most 70 kits evo2 / hebo / mhr etc show around 20bhp the 77 showed 23.5 bhp this was set up well but not necessarily on best components ,other pipes carbs ,reeds,tuning etc may yield further improvements
i think jump from 77 to 86cc should do 27 bhp no prob