I have a 1999 F4. Lately it has started missing out when it gets warm. When it is cold and starting up, it runs fine. As it warms up, it starts and feels like a plug isn't firing. Friend of mine suggested it might be a gasket that is bad causing the misfire. Just had the carb cleaned about 300 miles ago. Anyone else had this happen or have any other suggestions?

Thanks
SK

 

Sounds like it's running lean, when it's cold and the choke is closed it'll run rich but when the choke is opened, it'll lean misfire. When you cleaned the carb, did you only clean out the bowls or did you pull the jets out as well?

 

Might have been lean. Replaced the plugs to the higher quality spark and it fixed it. But now when I turn it off, I get a pulse of air now. Its not supposed to put positive pressure in the airbox system is it? Would be nice to just rip out all the extra emission crap for the air system.

 

so your saying it's running fine?

 

yeah.