Recently when I start the Big Bear 400 in the morning, after it has sat all night outside, it idles really high at start-up. Has happened now three mornings in a row. As I get it warmed up in neutral it continues to idle high. I have been turning it off and re-starting to engage into first gear, because I do not like putting it into first gear while it is idling so high.

OK, so as I give it gas in first gear and shift through the gears it seems to run fine. I did notice a blip or miss today when shifting gears. However, after I have driven for a bit, and come to a stop, the idle is real low and it is killing the engine. When I re-start the idle is still really low until I give it gas and take off.

So, idling high at start-up and after driving and engine is fully warmed up it is idling really low causing the engine to kill. This morning when I was on a slight upgrade in the horse corral, I could not even get it started. I pushed the ATV out of the corral, and went back 20 minutes later and it started up.

Not sure what is happening and/or what to do. Any helpful comments or advice would be most appreciated.

 

Yamahas are known for getting air leaks in the inlet manifold, so check the rubber isn't split. Clean the carb out, unlikely to be the problem but won't hurt. Check the choke is working properly, if slightly open, the bike will run fine when revving, but gets a much richer mix on idle. Check the throttle cable, and that the lever in the carb touches the stop when idling.