Atv help

[Barndog56]

I've got a 2000 Yamaha Kodiak 400. Had it out today and made a couple of laps around the property with no problem. Then the engine starts idling faster for no reason. Hit and let off the throttle a few times, but it didn't appear that the throttle was sticking.

I let it sit for a couple hours and tried again. It ran fine for a couple laps, then started idling faster again. So appears as though it comes on once it's fully warmed up. It was about 20 degrees today.

Any thoughts?

 

[Bill]

Check the vacuum lines on the carb. A vacuum leak can cause a higher idle.
Don’t know why it doesn’t do it cold. Maybe the rubber line has to warm up to get pliable enough to leak.

 

[Catscratch]

Spray ether (starting fuel) around the carb while it's idling to see if the idle changes speed.

Check carb base bolts to make sure they haven't loosened.

Check vacuums lines for cracks around fittings and attachment points.

Check fuel filter.

New carbs for that thing are $70 on Amazon...

 

[buckdeer1]

I have one right around that age but motor knocked and I quit running it, wish motors were that cheap guess I need to sell for parts

 

[jsasker007]

Carb could be sticking. Old gas will make internal carb parts gummy.

 

[Catscratch]

Does that thing have a fuel select, a petcock valve? If so I believe the line that comes out of the fuel tank has a screen filter on it (inside the tank). If so that screen could be clogged with debris or gummed up. Starving for fuel at low vacuum could cause idling issues that smooth out at higher rpm's and stronger suction.