XT600 Stutter

[az_mc_man]

I have a 1990 XT600 thats being obstinate. It was very cold blooded and hard to ride cold, and would stumble while riding, and cough and die at stops. I installed a larger main jet and made sure all passages were open, and all ports in the pilot jet were clean. The cold aspects were improved and it idles and responds to throttle input much better. But the surge, stumble and afterfire while riding easy (2nd gear at 20-25 and 3rd at 25-30) with steady throttle has increased. Can use some advice on this one.

[HardRocker27]

Have you tried adjusting your mixture screw? Sounds like you may be running rich. Check your air filter too.

[Kerchak]

I'm not familiar with the XT, but I had similar issues with a street bike last year (1987 Kawasaki Voyager XII). That bike has four carbs with short, stubby little rubber intake boots between the carbs and the head. You couldn't seem 'em with the naked eye, but the boots developed microscopic cracks that tended to make the bike run on anywhere from one to three cylinders. Banged on all four when in neutral, but put a load on the motor and it was just too much. Also, it was very, very cold blooded. Unless the thing was up to temp, I had to choke the heck out of it, even on warm days.

I diagnosed the problem thusly: I grabbed me a can of starter fluid (ether basically, available at NAPA or any auto parts store). I started the bike and let it idle. I then shot the starter fluid at the intake boots individually. If the idle increased, then I knew there was a vacuum leak in that boot.

Try that, and let us know what you came up with for a resolution.

Edited December 6, 2012 by Kerchak