I am thinking of buying a new battery as the old one, which is now 23 months old, tends to lose charge to the extent that the bike is difficult to start or won't start if left for 10 days or more or sometimes less. I need to disconnect the battery and possibly recharge the battery whenever I don't use the bike very regularly.

Anyway, it sounds like the battery has deteriorated.

Looking at the Thai (language) CBR forums, it looks like the Yuasa factory-installed battery may be a weak point. Some are recommending the FB alternative which is a 7 amp battery as opposed to the standard 5 amp Yuasa battery. The size is the same and the battery should last longer and hold charge for longer than the Yuasa battery.

Has anyone tried this battery?

No, but i've tried this and it works like a charm, according to them, battery also last up to 5 times as long.

http://www.amazon.com/PulseTech-SolarPulse-2-Watt-Battery-Charger/dp/B001D2V4ZE

The FB battery was a good replacement. Recommended.

Magnum is another good option. http://www.magnum.co.th/product_battery.php I'm not sure how it compares to the FB, but it is better than the stock battery for sure.