Query approved.

Try lubing the chain a bit....
You might need to clean it first by using WD40.....and then lube it good!!!
I faced the same problem with my bike couple of KMS back...

can you tell us what is the exact sound you hear.

it might be due to lubrication requirement or it needs to adjust tightness.

do you feel a kind of jerk when gears engage, are your clutch plates ok?

or might be possible some bearing has gone kaput.

try to locate the fault or atleast the location from which sound is coming by runing the bike on main stand.

I am getting the sound when I am pushing the throttle..i gt it serviced on saturday...i told the mechanic the same problem. he told by the end of service that it is fixed. again, i am hearing the same sound...its like cling...cling...and more i throttle, the more the clinging frequency increases...how to lubricate the chain and with which grease...
and is it like the chain is touching the chain cover..?

Hey there!!!
Grease would be an option but since the new 180 has open chain setup I suggest go for lubing instead of greasing......Grease will attract dust and ensure to destroy your chain sprocket.....
Simple tips like put your bike on main stand........
Switch on the bike, put it in gear (Usually 2nd or 3rd depending on RPM)
Spray WD-40 on the chain, atleast for three complete rotations
See how the dirt and extra spores drip near the stand....
Now your chain is cleaned but not lubed.....(the Cling sound may be because of accumulated dirt which is out because of WD-40)
Now lube the chain with use of Chain Oil...........
Clean the rear wheel and chain guard as you can expect additional oil droplets when the wheel is spinning in gear........
Test ride and check for noise......

If that clinging sound is really coming from chain than you can't help it. Just keep it clean, well lube'd and adjusted. I'm also living with it from past few months.
Tell me one thing does that sound come at constant speed? I guess it doesn't, right?