My son has a 50cc Suzuki Quad. It has been running pretty good for the last few years. Today was the first problem. I changed the spark plug and topped off the Oil resoivor. My son rode it for 15 minutes and it started having problem. It only runs when I have the throttle open. If it is at idle it will not run....

I put the old plug back in and it still does it...

Ant Suggestions.....

 

did you check your air filter...may be dirty

 

Well.. I got it running a little better..and I just sold it this afternoon...That was my main concern I did not want to sell it if it was not running good...but it was running good when I sold it