Weird Noise

[rsaxa]

My son has a KX 65, I have had nothing but bad luck with this bike, from the eng lower end blowing and now there is a weird sound to it when I let the throttle go, like a low buzz or a whirl. I have checked every bolt on the bike to make sure that they are tight. I removed the cylinder to make sure the lower bearings were tight and they are, replaced the piston. Still the same weird sound???
The Bike is running with lots of power, its just that sound that is driving me NUTS. Something I was wondering, does anyone use belray in the transmission? After running the bike, how does the oil in the sight glass look? Does it look like a bunch of little bubbles in the oil, and how long does it take for the oil to settle to its original state? I am wondering if I have an air leak somewhere?? Or whatever it is causing this sound. I listened to another kx 65 and it did not have that sound.

Thanks for any help,
Bob

 

[kdx633]

little bubbles normal,may take hours to settle,when draining oil is there white pukey stuff in it?had same noise in sons kx 85 only did it when at operating temp.tore my hair out looking for it.turned out to be clutch free play was too tight and when bike warmed up it was putting load on throw out bearing making it buzz.wiw

 

[Red Rider 53]

It could mean that it is time for a bottom end rebuild. There also could be an air leak. ( I read that in Eric Gorr's Off-Road Motorcycle Performance Handbook)

 

[rsaxa]

How would you check the clutch plates for tightness? I have not drained the oil to check for water in the oil, but if there is water would that be from the water pump? would that involve a complete teardown of the eng? Or are there some seals on the water pump that can be changed.

Thanks,
Bob

 

[Jasle]

do yourself a favor and put some epoxy in the 3 little cutouts behind the stator. these motors tend to leak air due to porosity of the case in this location which usually leads to the bottom end bearings going south. I would do a pressure test to see if you currently have an air leak though. hows the plug?

 

[kdx633]

How would you check the clutch plates for tightness?
warm the bike up good and hot, check clutch lever free play.adjust accordingly

Thanks,
Bob