My son bought a 2000 R600 with 5K miles. The bike is a bit difficult to start. Looks like the choke has difficulty setting. When he starts it initially in the morning, he has to rev it up quite a bit to get the choke to set and sometimes also hold the throttle open until the engine gets up to temp., about 120 degrees. We live in Florida so this time of year, it's still never below 70 degrees. We changed the spark plugs but that didn't help. There are no mods on the bike, except for an add-on Yoshi (sp?) exhaust.

im not sure if thats fuel injected or not. If it is and you've got a full exhaust system it might need to be remapped. Try spraying some carb cleaner in your carbs if not FI could be your problem.

Fuel Injection of the 600 didn't come out until 2001.....Sorry can't help with the real problem.....

I had a '98 600 and had the same problem. The choke is quite touchy. Try pulling the choke all the way back and give just a little twist of the throttle when turning over. As soon as it fires, move the choke back about half way until it warms a little.

Hope this helps.