psr sir always hits bull's (or bike's??) eye!!
You are running lean (hot) when in Coimbatore that's why engine becomes harsh. Whereas Ooty being a higher altitude place engine will only perform good when running lean [lean compared to normal setting] it doesn't stay lean in ooty because of thin air & higher altitude.
Try out the richer setting as suggested by psr & report back a positive news.

Re: Hero Honda Hunk - Poor Pick up, Too much vibration and Poor Pulling.

Hi All,

Recently I am noticing a bubbling sound(piston struggling to pump, with choke it is fine) from the Hunk bike engine and that too happens when the engine is started in the morning or it can be said when the engine is cold. The sound disappears after sometimes when the engine gets heated up. The bike was serviced couple of weeks back and has run around 24K KM's. Checked with a local mechanic and he says the sound could be related some shaft problem in the engine. Request to provide your inputs if any one else have faced the similar problems.

Regards,
Ashwhin.