jimmydee

Thanks. It has an R cam so I think I'll try 2 and 4 thou. I've had a phone call from a guy who read the forum thread and he said I should go back to a standard D40 needle instead of the D23 which I was (mistakenly as it turns out) advised to use. I've also gone down to a 100 main jet. The motor is now revving with no misfire. So hopefully I can concentrate on riding.

Thanks. Engine was rebuilt in December 09. Still plenty of compression when its hot or cold. No burning oil.

Thanks. The engine is fine at low revs and mid range. Also I can crack it open to full revs no problem. It's only at high revs when blasting up a long climb that it misfires. When I shut off throttle it backfires once. No spitting in carb at all. No smoke or burning oil. Engine had new guides fitted in December 09 and they were free. It might be that I need more clearance in tappets. Currently 2 and 3 thou.

Thanks. The air filter is a 1/2 moon SM type with a Twin Air foam filter. It has a wire cage to stop it from being deformed or sucked into the inlet. It is connceted to the carb by means of approx 1" length of car radiator hose which is tough stuff.

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