For those of you who haven't got a clue what a lakh means, it's Indian speak for 1,00,000. Ride safe!
Try advancing the ignition timing a bit. That might help.
if you are still running a points ignition that uses a mechanical advance you might make sure that is free to move and advancing properly...Good luck
With miles that high and those symptoms, if the timing is good I would check for a carboned up exhaust. Runs fine slow, but no top end power. Two strokes would do it all the time in the good old days