I have a 300 4X4 that starts everytime and runs good for about 5-10 seconds and then sounds like it is missing if you come off idle any at all. Will idle all day but if you touch the throttle it sounds like the miss you get with a rev limiter. Have tried a good CDI and that did not fix it, and the Other unit ran good. Any suggestions? Thanks, TORK.

 

When is the last time you changed plug? Also when is the last time it had carb work. Would also pop some water eliminator in the tank.

 

New plug and carb and valve work done recently. Am going to pull carb down again and check but just acts and sounds like ignition miss. This unit has a history of sitting with fuel in it so I have had the carb off several times, also set valve clearences a couple times in it's life. They don't use it for long periods of time and then when they need it they have problems.

 

Check spark plug gap. When cleaning carb, make sure to pay attention to the air/fuel mixture screw as this could cause it to sound like it's missing. No sure what grade gas you're using but, as a mechanic, I recommend that customers use high grade. I realize that it costs more but it contains less abrasive and corrosive particles than the lower grade. Lower grade fuels plug carburetors and eat away gaskets. Also check to see if there are any bare wires. Hopefully this can help you out.

 

Carb was a mess, air filter was dry and extremely dirty. Cleaned everything up and still no difference. As I stated before will start right up everytime and run fine for about 5 to 10 seconds and then go to missing just like a rev limiter, will idle all day long.

 

Found out that if I turn ignition switch to the light position it runs great. Turn back to run and it misses like before.