Hi, I have a 2002 Zip 50 which I recently bought a Loe vince TT exhaust for. The problem is when I fitted the exhaust the bike will not run(no power). I took bike and exhaust to my local bike shop and they couldn´t get it running either but they did fit a standard, derestricted exhaust and set the carb up for me and told me it was running fine. Everytime I go out on the bike it runs ok for a while then looses power at full throttle, if I let the throttle off then back on it go´s agian.Can anyone help please? Also does anyone know the correct roller weights and jet size to use on this bike with the loe vince exhaust? Any help would be great as I need this bike to get to work. Thanks Andy