I have a 230cc Tiger Cub motor with a Dellorto carb, Armac exhaust and PVL style (UPB) ignition. The slow running and mid range power is okay but on long climbs where it requires high revs it misfires very badly and often does not make it up the hill. I have spent the best part of a year trying to get the motor to run correctly but I am getting nowhere and going around in circles. I have asked many fellow Cub owners for help but it mystifies us all. I have checked and double checked the ignition timing which is spot on. I have tried all sorts of spark plugs, main jets, needles and pilot jets but still the problem persists. Currently I have a 35 pilot, 105 main jet and a D23 needle set in the third groove from the top. Mixture screw is 2.5 turns out. Can anybody help? Thanks Jim