my nut is welded to the pulley any ideas on how to get that off?

 
Now that you are in the right place, here is an answer.

First, why did the previous owner weld the nut (and I bet he welded the pulley itself too, didn't he?) to the output shaft?

Previous owner was unscrupulous.  Front pulley splines were totally stripped out and he just wanted the shebang to hang together long enough to palm the mess off on you.

Answer, don't mess with it at all -- if you grind that nut and pulley free you are signing up for a full split the cases tear down and the labor charges and parts to do that will cost more than a used replacement engine would cost.  

If it is hanging in there good, let it be.

Should it ever manage to break itself free (very unlikely) you have your answer right there already.

First off sorry for posting in the wrong section was just reading and forgot where i was. Now to answer JOG's question i have had the bike for nearly ten years but it was in storage for most of that time and i havnt really been interested until lately because i need something to get to work and back and this seems like my least costly option.

As for the spline i think the nut is just welded to the pulley meaning i could probably get it all off in one piece but a socket wont fit on there anymore. I would just leave it alone but it doesnt look to be welded all that well and i wanted to eventualy do a chain conversion.

thats what i was thinking but feel like i run the risk of rounding off the nut thus making it almost impossible to remove

How much weld metal is in there?  If all he did was tack it in place in a couple of places, you could use a Dremel with the really thin cutoff wheel to surgically cut through the welds.  He was a jerk to do this in the first place, so many he was jerky enough to not get much penetration in the welds.  If he did a high heat, high flow, and high amperage MIG welding sesssion,.. and slobbed in lots of metal,.. you're screwed. If there isn't much metal added, though, you can do some miraculous things with that thin dremel cut-off wheel and a lot of patience.  It can make some real tidy slices.  Make sure to wear ear muffs and goggles.

A picture of this would be great so that we know more of what your dealing with.  

After seeing said picture then we can make more informed advise on what your options are or if your basically screwed.

R.F.

i will try to borrow a camera from somebody and get pics, theres a decent amount of metal there, crappy looking welds though. The thing with just leaving it alone is it was in storage for about 7 years and sitting out in the weather for another 3 and i dont know how safe i would feel driving it without replacing the belt.

One other consideration, if it has been in storage for 7 years, and out in the weather for three, the tires are probably unsafe, even if they look okay, and even if they were good the last time it was used.