YZ125 runs good but fouls plugs after it is warm on trying to start
I am sure I have seen something posted like this before but can't find what I want. My buddies 2000 YZ125 starts and runs great with a new plug in it. He can turn several laps come in and shut it off, pull the plug out and look at it. It has good color to it, that nice tan mocha coloration, he also says it runs like a champ during that time frame. He goes to start it and it ends up fouling the plug out. The other day he couldn't even pull start it using a tie down and a friends quad. Will anybody point us in the right direction. We have adjusted the jetting and we really don't think it is that because of the way it runs and plug coloration. One of us thinks it might be the ignition, I say it could be some type of air leak. I don't know how new the top end is on it. As far as I know everything is clean as far as air filter, carb, ect is clean. I think it has to be something simple so if you would launch some ideas our way I would appreciate it.
I am sure I have seen something posted like this before but can't find what I want. My buddies 2000 YZ125 starts and runs great with a new plug in it. He can turn several laps come in and shut it off, pull the plug out and look at it. It has good color to it, that nice tan mocha coloration, he also says it runs like a champ during that time frame. He goes to start it and it ends up fouling the plug out. The other day he couldn't even pull start it using a tie down and a friends quad. Will anybody point us in the right direction. We have adjusted the jetting and we really don't think it is that because of the way it runs and plug coloration. One of us thinks it might be the ignition, I say it could be some type of air leak. I don't know how new the top end is on it. As far as I know everything is clean as far as air filter, carb, ect is clean. I think it has to be something simple so if you would launch some ideas our way I would appreciate it.
Last edited:
