I got it for 100 dollars, didnt run. I put a bunch of new parts on it, fixed the wiring idiocracy from the previous owner(wire nuts. everywhere. bad splices. bad connections) Changed oil, new lots. Then I go to start it, cranks over and runs!!!!

However, it runs at a REALLY fast idle. Not so fast I cant give it throttle, but it only goes a tiny bit higher with throttle. I did put a new carb on but reused the throttle cable "cap" ontop of the carburetor, just used new gasket(same with choke). I don't think that would be an issue... but idk. I turned the idle set screw(on the bottom) all the way down, basically its hardly threaded in(threaded out lowers idle per service manual). Still idles fast.

One thing I have noticed is the tube duct thing from the carb to the intake manifold has.... cracks? Around the base of the flange to the intake manifold. Is it possible those are causing the idle? Im not sure how its cracked... but I see they can be ordered(looked at yamahs part website). Is that something that happens?

Are there other things I should look at?

Im mechanically inclined but ATVs are a beast i Have not yet mastered. Willing and love to learn, though.

 

Sucking in extra air could very well increase idle speed. Also causes a very lean condition, check your plug...should be tan- brown color.

 

Well, this atv hasnt run since the 90s... and its a new plug. i think it would take a while to get tan and brown.

 

Are you sure there is some play in the throttle cable when on idle, some people try to adjust idle by shortening cable on the cable adjuster instead of the carb idle stop screw.

Never tried it myself, but an air leak in the carb manifold can be tested by spraying oil or carb cleaner onto it, this temporarily blocks the leak and changes engine note.

 

I did not play with the cable, and the throttle... pole? Sits fully down(and the needle, too) when the throttle isntpressed and goes up with the throttle being pressed, but its not a bad idea to look into.