I had this recurring issue with my Avy that my engine died whenever I downshifted or there was no acceleration. I changed both the spark plugs (Mico twin types) and the mech retuned the engine. The beats interval sounded better but the problem still persisted.
He said it might be the carb, so I left the bike with him for a whole day and he said that there was some rust on the jet and it had to be cleaned, also fixed the housing clamp for the airfilter due to which the clamp that holds the pipe that gives air to the engine was loose every once in a while.

The bike sounds good now and the issue is resolved. But I noticed a considerable reduction in the acceleration and pickup. The vehicle seems to be really sluggish.

Any clue why this might have happened? Also when I reduce the acceleration slightly to upshift/downshift the feel of the accelerator is not smooth. I guess the cable can be greased from inside and this might be solved. Am I right or is there more to it?

Thanks,
Beo