What condition are your chain and sprockets in? If you pull your clutch in while coasting does your chain sound excessively noisy?
Often a good clean and lube can transform your sprockets and chain, I clean mine once a week religiously and douse in ptfe. Stripping and cleaning your chain regularly certainly prolongs it’s life. It’s important not to spray over old lube, as this has picked up lots of road dust, and is simply acting like a fine rubbing compound.
The jury is still out on the best cleaning agent/lube to use, there are any number of threads dedicated to that 
A badly adjusted chain is often the cause of problems. Too slack and it’s at risk of leaving the sprocket and doing some expensive damage, too tight and you are putting excessive stress on your output shaft and running the risk of the chain snapping. As a very rough guide to chain tension, with the bike on it’s side stand, you should be able to move the lower portion of the chain up and down about an inch. Refer to your owners manual for precise values.
However, if after lubing the chain is still noisy, becomes noisy quite soon after treating it, or has a stubborn stiff link that clanks periodically over the front sprocket, it might be time to consider a new chain and sprocket set.
There are various ways to tell, initially a visual check is a good start. The front sprocket wears fastest, so removing the sprocket guard periodically and checking it is never a bad idea. You are looking for a symmetrical sprocket, this picture demonstrates the difference between a worn and new front sprocket
The back sprocket is prone to wear too, especially if a prior owner has skimped on cost by simply replacing the front.
Chains tend to stretch over time, some bikes have a stretch indicator on the chain adjusters that act as a guide. Failing that, your owners manual contains details on chain stretch. This usually involves measuring the chain across a number of links, then comparing it to the tolerances given in the manual.
A chain stretched beyond the recommended tolerance is dangerous. It’s not common for a stretched chain to snap, but it’s certainly more likely.
Occasionally a single link will become stiff, ticking every time it passes the front sprocket. Cleaning and lubing masks the problem for a while, but in my experience it’s usually a sign that the chain is on it’s way out.
If all that checks out, the noise might be the result of a worn rubbing strip. They lie along the swing arm under the chain, preventing the chain from wearing the metal beneath.
They don’t last for ever, and when they wear through, you risk damaging your swing arm and chain.
I’m supplying and fitting quality DID chain and JT sprocket sets for a wide variety of bikes.
If you live in North London £150 inclusive.
Destinations further afield will incur a small extra charge to cover my traveling time.
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