Bike stalling when hot

[tobike]

I have searched and not found a thread specifically to this topic. I have a 1999 KDX220. When I ride, after about 45 minutes when the big is really warm, the bike stalls frequently. If I hit the brakes hard, pull in the clutch going downhill, let it idle going downhill, etc., it dies. If I keep my hand cranked on the throttle, it won't die, but if I back off it, it dies. Otherwise, it tends to idle fine and it only does it after riding for a while and the engine is hot. What causes this? Do I need different jets, reeds, etc.? Help!! Thx

 

[83MX80]

have you cleaned the carb? are your jets right for your altitude? that seems wierd to me that it even downhill it dies. does the rear tire lock up?

 

[tobike]

I'm not much of a mechanic and haven't done anything with the carb at this point. should I begin taking it apart and just cleaning it? Yes, if I don't have the clutch in, it will lock up the back wheel. In soft soil, even going down a big hill, it won't roll start unless I kick it up to a high gear.

 

[KDXruss]

Your idle speed should be adjusted while the motor is hot.

 

[adam728]

Is the bike stock? Has the jetting been changed at all?

I would start off with cleaning the carb. When was it last done? While the carb is off I would also pull the intake boot and slide out the reeds for an inspection. Look to make sure they are closed all the way and there is no gap around the edges. If there is, they need to be replaced.

Another possibility is that your low speed jetting is off. If it is running rich then as the engine warms up the idle speed will become lower and lower. Proper setting of the air screw can cure this, but only if the pilot jet is within the ballpark.

 

[ridejunky]

Sounds like your throttle valve (slider) is hanging up when she warms. Will it die of you run it fast then pull in the clutch, even if you aren't going down hill? If so, take it out and look for signs of wear and smooth operation.

 

[adam728]

Sounds like your throttle valve (slider) is hanging up when she warms. Will it die of you run it fast then pull in the clutch, even if you aren't going down hill? If so, take it out and look for signs of wear and smooth operation.

If it were hanging up the bike would rev on it's own, not stall out.