Posing on behalf of a friend.
Duke 200 BS3 First Model.
The vehicle has done more than 60000 km.
It recently developed an issue with fuelling which caused the bike to idle above 2000 RPM.
Upon inspection, the throttle body was found to be stuck and not closing completely on releasing the cable.

Tried spraying WD-40 in the spring and joints but it was useless.
Finally, the throttle body was disassembled and cleaned, which fixed the issue.

If anyone faces a similar issue, try doing this before replacing the throttle body.

I am attaching some photos.

Thank you for the post. Considering the KMS done and the carbon build up around the throttle body plate, this is bound to happen. It's advised to clean the throttle body every 25k kms for optimum performance.

Cheers!
VJ

My Duke 200 2016 has crossed 1lakh kms.

Recently during cold starts the bike kind of lags. Upon pulling the accelerator when in first/second gear (with cold engine) the bike gains initial speed of around 5-10kmph but upon further pulling the accelerator the engine just doesn't rev for like 2-5seconds & the bike just continues moving without any acceleration. After those 2-5secs the revs start to increase.

To counter this lack of response I have to raise the revs in half clutch to avoid this lag.

I have replaced the chain sprocket set already recently. Throttle body was cleaned around 14k kms back. Oil & other filters replaced 1k kms back. Spark plug is 14k kms old.

Clutch plates never replaced. Fuel pump never replaced.

Engine sound has also changed but can't express this sound in words.

What could be the problem of this engine rev lag.

Check compression reading. At 1 Lakh Kilometers the Piston Rings and or the bore wear had taken place leading to loss of performance ,which is mostly felt in cold condition.
Otherwise your Throttle body needs cleaning.
First check and clean throttle body , then check Compression.

I used LiquiMoly speed shooter additive and there is some improvement now.