I have a 1999 300 4x4 Cat. when it is cold it fires up good and takes a while to warm up. If I shut the choke off it will shut off until it is warm. I have noticed when I shut the lights off that the exhaust is red. What could be causing this. I think it is running lean but not sure. Any ideas would be greatly appreciated.

 

Sounds like a lean condition. A fuel system cleaning is in order first. My personal opinion is if you are going to go through the hassle, do it completely from gas tank to motor.

Remove the carb, take it apart and clean it completely. Buy a carb rebuild kit and replace any suspect parts.

Drain the gas tank. Flush the tank clean. I use water and flush it well first. Then I use a degreaser mix and let it soak in the tank and fuel lines. I flush it again with water. Then I use Sea Foam in the tank and the fuel lines going to the carb. Let it soak overnight. Drain and then flush with some acetone. The acetone will dry out any remaining water as well.

Put an inline fuel filter between the tank and the fuel shutoff while you're at it.

I've had great success doing it this way.

 

Would that be the cause of it firing up but the exhaust being cherry red when it is turned off?

 

I believe the exhaust being cherry red is a sign of a rich condition. Too much fuel to burn in the cylinder so it goes out the exhaust valve when it opens and burns in the exhaust pipe.

If you choke is sticking or not working properly then it is enriching the fuel system. Definitely need the can cleaned as a start. If you check your spark plug you would know for sure. Tan = right mixture, Black = too rich, and a very white colored tan is too lean.

You may also want to replace the plug if its too black.

To clean I remove the carb from the machine, and remove the float bowl (be careful as there is a small plastic spacer than will fall out). Clean with automotive carb cleaner and spray it in each hole you can find (watch your eyes). Then I use compressed air and blow air through all the holes as well (again watch your eyes). Then I put it back together and put a bunch of Seafoam in the fuel tank. Change the plug and fire it up and see how it does.

If you continue to have issues then check the air mixture screw (should be about 1 3/4 to 1 7/8 turns out) if you have a Keihin CVK36 carb.

No matter how you clean it an in line filter is a good idea OR use Seafoam in every tank of fuel.

SJ