Are you holding the axle with one wrench while you tighten the nut with the other so the axle can't turn when you tighten?

 

I hold the left side with a vise grip while i hammer the **** out of the other side....

 

^^^

What he said. Maybe you already know this?

You gotta hold the weld nut in place on the left side while tightening the cone nut on the right side. Any movement at all.......you've got to do it over.

And yes.......your belt will most likely be looser in some locations than others on the rotation of the belt. Adjust from the tightest spot you find.

 

If the motor mounts are going south it wont stay adjusted. That would be the first thing i would check.

 

Don't forget to put a little "sharpie" mark by the welded nub...
After torqued looked to see if it is in the same position.
Does the torque value on the axle remain the same after it's loose?

Rotate the wheel for a minute or 2 and then check the belt in various positions...

or is is flat out really loose?, if so it's got to be the axle and the little welds, or try an extra 19-20lbs on the torque. also you still have the little locking clip for the axle nut?

 

+++1 One of my friends found they were loose.

 

See what happens when ya ride a "old" bike..lol.. makes ya wonder why they did away with em now don't it??

 

Are you doing it with the wheel raised up off the ground, or on the jiffy stand??? Made a difference on mine.