Hello folks. Its been a long since my last posts in here.

Unfortunately I am experiencing some major issues while trying to start the engine. If I leave the bike deactivated for some hours (i.e. 8-10 hours) then it starts really hard. I try to start it but the battery level drops abruptly so it doesn't start at all. Then I have to charge the battery and then if I am lucky it starts, if not maybe I have to repeat charging once more. Then if the bike starts it works excellent and after short duration stops, it starts without problem, except if it stays off for more than 8 hours. I thought that this issue was relevant to temperature but I realised that its not. Today even though I charged the battery three times the engine didn't start at all.

Any ideas ?

V-twins are hard to crank and from what you say your battery is not good.
People had this before and tried all sorts of different things to come to the conclusion that the battery is bad.
Get your battery load tested before you try anything else!
Also check all cable connections to the frame and starter motor if the battery is fine.
If that fails try to borrow an amp meter in clamp form that does DC and check the current draw of the starter while you crank it. It just clamps round the negative or positive cable and tells you how much Amps the starter motor draws. If you need a compare I can test mine to give you an indication how much it should be.
You might call in the help of a vehicle electrician if this is behind your knowledge.
While you do this check also if your charging system works fine to charge the battery, the rectifier/regulater does fail form time to time.

As Guy has said most likely your battery. If it's more than 3 years old replace it. Once you get the bike running you can eliminate the charging system by checking voltage across the battery terminals to assure the it's getting the proper voltage.

If your battery is lead-acid you should always keep it on a battery maintenance device such as a Battery Tender. I got 5 years out of my OEM Yuasa which is pretty damn respectable. Just replaced it with an Earth-X LiFe battery and am inpressed with it's performance and light weight. Not failed to start the bike once (on the second revolution no less) and doesn't require a maintenance charger.

IF it were me...and it was, I'd go with the Earth-X. Liked the way it performs so much I just bought one for my desert bike.

Hello all and thanks for your posts.

The battery is not older than 3 years. I own an optimate 4 battery tester and charger. It doesn't indicates that the battery is crap. It has 4 levels (excelent, good, moderate, weak) and it qualifies as one level bellow excellent. Unfortunately I don't remember the battery's brand.

Not sure what those ratings relate to as far as voltage.

How old is the battery? I would presume unless it says excellent it will not start your bike.

Thanks everybody for the replies. At Optimate it indicates that the battery is at medium condition (during the retention test it indicates one green and a yellow led).