Greetings!

My 2005 'GS500F requires me to open the choke all of the way in order to start. Regardless of how warm the air tempeture is.

This would be OK on a cool Fall morning. However, if I ride my bike 15 minutes to Wal-Mart and come out 20 minutes later, the bke is "cold" and I have to open th choke all of the way as if the bike were sitting there all night. The ambient air tempeture is about 90 degrees F.  During operation or idling at long stop lights, the bike does fine. So, the problem is not with the idle speed. This cold blooded phenomenon occurs only at start up.

Any ideas? Would installing a dynoJet help?

Cheers.

I always use full choke to start my bike, even in the Australian summer.

And yes, I think a rejet helps as the bike is setup to run super lean for emission reasons.

How many miles on your bike?   Are you still in the break-in period?  I had the same problem with my '05...it just needed an eternity to warm up when I bought it, but at the 600-mile service, the stealership adjusted the valves and it was much better.

It runs great now...starts right up every time, even after sitting for a week or two.

hmmm ..  i'd take it to the stealer ship and have them check the valves if you have not done your first service. you might have one going out of wack . not a problem they do this . if you are past your first service (600 miles )  then take it in have them do a valve check on it if you can afford it . unless you think you can do it your self

Yes mine was this way too. You need to remove the brass plugs and  adjust the mixture screws on the bottom front of the carbs. Turn them in until gently seated and count the turns. Then turn them out. You should be around 2-1/2 to 3 turns out depending on elevation.

Welcome!

I would suspect valves need adjustment, too.