CV carb upgrade...what do I need??

Hi Guys I'm a forum newby looking for advise please as I'm pulling my hair out trying to sort this out. I'm based in the UK and have recently acquired a year 2000 HD Sportster 1200 XL Custom with only 3000 km on the clock, it come over apparently from an eastern block country and I've rectified numerous electrical faults, fitted all service parts, filters, oil etc, fitted a carb service kit and set float height as per spec, also fitted Screaming Eagle slip on's and a K+N air filter its otherwise standard, it churns and churns from cold start up then runs fine on choke however if I rev it even slightly ( unless up to running temp) it hesitates and back pops......I'm thinking of rejetting carb, new needle jet etc etc to alleviate this problem, what pilot jet, main jet, needle jet and idle mixture settings would you expert guys recommend for this bike and uk summer use, many thanks Janno

Welcome, Not up on Sporster carb. Is it a Keihn CV? If so recomend contact CVP. They should be able to send you what you need first time. Do what they say and you should be good. To lean now and possible detonation when hot.

I don't think you have a jetting problem at all, unless a jet was installed improperly. I'd check the vacuum line first, or just replace 'em all. Check your carb's diaphragm for a tear, too. Please let us know what you find.

True as Red Rider did point out , check what you did again. Was the bike running OK before the muffler and air cleaner change?