I don't know much about my ATV but I am hoping that someone can help me figure out what is wrong with my '86 250 Quadrunner. Every time I take it out it starts making a humming noise. I have taken it in 3 times and they have been unable to fix it.

The noise is coming from the rear of the quad and sounds similar to when you drag a wet finger around the rim of a crystal glass (sorry for the goofy description).

Any ideas?

 

bearing heats up and is going out ??

 

Brakes dragging?
Skid plate rattling?

 

deanz400:
that could be. is that something a mechanic would have a hard time catching? its been happening for about two years, w/ little use, how long does it take for a bearing to go out once you hear the noise?

thanks for your thoughts!

 

GrnXnham:

Each time we have taken it in we have been told it is not the brakes, also, I haven't noticed them catching when i let off the throttle. I will check the skid plate.

Thanks!!

 

probably just need to check any thing that rotates ,bearings and chain and such

 

Does it make the sound when idling or only when riding? If it does it only when riding, jack up the rear end and have someone sit on it and gas it while you probe around the rear end looking for the sound.

Sometimes a humming noise can be something as simple as a rattling plastic fender.