help wanted - starting issue (requiring lots of choke and now not starting)

[jdmr]

I'm hoping I could get some opinions on the likely cause of a problem I am having starting my bike.  I'll give you a bit of history and the problem I'm having right now...

I bought this '89 GS500 in July.  It had been sitting for roughly two years, with gas in the tank.  (I used this gas once I got it on the road)  I don't know when/if it was properly winterized last though I do know it HAD been winterized when it was being ridden.

It was running well when I got it so I didn't think too much about maintenance at the time.  I had new tires and fork seals done for safety and I was good to go.

I immediately started to notice a bit of a problem with starting and the amount of choke required, even on hot summer days.

all summer when starting with no choke, it would stall out immediately or not fire at all.
half choke and it would start and rev around 1200rpm.
if I would give it a bit of throttle right away, it would stall out so I would just wait until the revs went up.  It would go from 1200 to about 3000-4000 very suddenly and I would reduce the choke to bring it back down to 1200. I could then give it some throttle without stalling out.  At this point though I would still have to leave the choke on a bit for about half a km or it would stall out at a stoplight.  until I really got it warmed up, with no choke it would rev under 1000rpm and sound really weak.

On Saturday I went for a longer ride and was on the highway for about 20 minutes, riding it a bit harder than usual  (I mostly take 50-80km roads within the city).  I went to start up yesterday afternoon and it just would not.  It would sound very close to firing but it wouldn't happen.   I tried a few hours later and still the same, even with full choke.  I tried a few more times and I think my battery is too depleted to actually turn the engine over anyway.

I am really not very mechanically inclined but my first thought was that it had something to do with the gas having sat in the tank and then being run through the bike.  I spoke to a friend of mine who suggested I check the air filter first to see if the engine is being starved of air, otherwise it's likely a carb issue.

Thoughts??

[black and silver twin]

all summer when starting with no choke, it would stall out immediately or not fire at all.
half choke and it would start and rev around 1200rpm.
if I would give it a bit of throttle right away, it would stall out so I would just wait until the revs went up.  It would go from 1200 to about 3000-4000 very suddenly and I would reduce the choke to bring it back down to 1200. I could then give it some throttle without stalling out.  At this point though I would still have to leave the choke on a bit for about half a km or it would stall out at a stoplight.  until I really got it warmed up, with no choke it would rev under 1000rpm and sound really weak.

This sounds normal for a bike with stock jets. My gs did this from the day it was new in 07 untill I rejetted it this summer, it now starts much better.

On Saturday I went for a longer ride and was on the highway for about 20 minutes, riding it a bit harder than usual  (I mostly take 50-80km roads within the city).  I went to start up yesterday afternoon and it just would not.  It would sound very close to firing but it wouldn't happen.   I tried a few hours later and still the same, even with full choke.  I tried a few more times and I think my battery is too depleted to actually turn the engine over anyway.

Check/charge/jump/replace the battery and put new gas in. if it still has problems check the plugs and probably replace them. then clean the carbs and consider doing a rejet.

Good Luck

[jdmr]

the gas in it now is new, I just filled up about 3 days ago.  we took out the spark plugs and looked at them.  they appear to be fine but I wasn't quite sure what I was looking for. 
once I give it a charge, I'm not sure what else to do short of having a carb clean done, potentially unnecessarily.

[black and silver twin]

The plugs should be a light gray color with very little carbon build up. the electrodes should be unworn with the proper gap.

the old gas could have easily put deposits in the carbs or lines. try opening the drain screw on the carbs to make sure gas is getting to the carbs. The petcock needs to be in the prime position for this to work. if gas comes out note its color and consistency and smell.  if it has debris in it clean the carbs, if it stinks like rotten stuff clean the carbs, and if its dark brown or black or any other not normal color clean the carbs. if no gas comes out of the carbs pull off the fuel line and make sure gas comes out the line if not replace the fuel lines.

then if still no gas comes out of the lines one of the petcocks is probably clogged (there are two, one on the bottom of the tank, one on the frame). if fuel comes out of the lines but not out of the carbs then its time to clean the carbs.

also if the battery is two years old or more and has been sitting its probably bad. it may have enough juice to turn the engine over but may not have the power to also fire the coils at the same time. you can jump start the bike with a car battery (car turned off)