2006 GS500F
Problem:
Appears to now be isolated to when it is cold out. At around 50 degrees the bike will crank for 10 seconds before turning over. Lower temps than that I have not been able to get it to start and have even killed the battery trying to get it to turn over (should the battery die and leave the starter just clicking after 2 minutes of trying to get the bike started??). If I get it turned over with full choke it will idle at 2k and creep up to 4k. If I let it warm-up at 4k for 5 minutes it will maintain an idle of  1.2k which I set previously.

Work I've done:
Replaced the spark plugs. Had the battery tested at autozone. It is good and the electrolyte level is good. I left the bike outside with the battery tender hooked up to it last night and it turned over immediately at around 40 degrees which surprised me. I checked for parasitic drain and the bike is only pulling .06Vs with the key to the off position. With the bike at 4k I read 13.9V at the battery. I commonly read 12.4-12.8 at the battery with the bike off.

Is this just a matter of the battery working better from being very warm? The bike sat for a number of years and I'm going to rebuild the carbs in the next few weeks. I don't know if that will help.

The recommended battery for the GS500 (according to Haynes) seems to be the Yuasa YB10L-B2/YB10L- A2 (11Ahr).  This is a lead acid type which generally is an under performer in colder weather compared to an AGM type.

Lead acid batteries really hate the cold (especially below 10 degrees C) - Battery capacity for lead acid typically falls by about 1% per degree below about 20°C. This includes a slower charge rate at lower temperatures. If it is 10Deg C outside you will have lost 1Ahr, if it is 5 degC it will be closer to 2Ahr.  At this temperature I wouldn't expect more than a few minutes of cranking from a battery this small. If you have short runs you may not be getting enough energy back into the battery for that next start.

I run my bike in cold weather (somedays below 0C) and have noticed a big difference with an AGM battery (MotoBat MB10U 14.5Ahr). 

One thing you could try is getting a car battery in there and checking how quickly it starts with a decent amount of energy behind it...

Short rides I don't think is a problem:

• Saturday afternoon -- 65f (18c) started up OK then did a 200 mile ride.
• Sunday morning -- 10am 35f (2c) degree bike would not start, killed the battery trying to start.
• Sunday night -- 40f turns over first try while hooked to the tender after it was on the tender for 4 hours. Leave off tender overnight.
• Monday morning -- 50f cranks for 10 seconds and then starts.

The MotoBatt looks good but ouch on that price tag. Do the batteries in these bikes go for much on craigslist or can you get some cash for them at a battery warehouse to offset the cost?

Bought the MotoBat MB10U on amazon for $80 and it'll be here Thursday.

Let us know how it goes - can help try diagnose it further, but suspect that an AGM will make a big difference. 

My bike doesn't like starting cold either. Starts up no problem with a warm battery (even if the bike is cold).

I use a trick someone else had mentioned, I believe adidasguy -- crank it a revolution or two and let it sit around 10 seconds, then try again. Worked exponentially better for me than just continuously cranking it.

Definitely update me on if that battery helps though, I'd love not having to take my battery inside every night to know I'll be able to get to work the next day.

Could always get it a blankie 

http://www.amazon.com/Kats-22200-Watt-Battery-Thermal/dp/B000I8XD9E

what i like to do in cold weather is put it on prime, press the starter, and jiggle the choke a little to get er going. only a little bit at a time though, dont hold the starter down for too long. you will kill your battery. try to start it up  for 5 seconds. if it doesnt start after 5 seconds, then wait ten seconds and try my method for cold weather. you dont want to kill your battery trying to crank it over. not only will that damage the battery, but it can also damage your starter. the starter pulls alot of amperage when it is used and this creates alot of heat and that heat can damage your starter. 

Good post Kiwingenuity, some stuff I didn't know before.

It can be a nuisance starting with the lead-acid battery in Sydney, Australia during the winter (which I have never seen go below 3 degrees Celsius), in the USA where it gets much colder will be a real pain I imagine.

Think it is definitely the cold. I stored the bike inside overnight, wheeled it outside this afternoon and it started right up. Battery will get here tomorrow!