How do I square up the rear axle to the frame
 

as you can see in this picture the rear axle is not square to the frame it is about 1/2" to 3/4" off I tried to loosen all for bolts like I was going to adjust the chain but I can only get it to move so much. Any ideas???
Attachment 12509

Not sure what bike you have ,but I have had several China atv’s with rear axles welded crooked just like your picture or some even worse .Cut and paste was the only fix .

Agreed. I tried to find an old example pic, but they were all stored in PB. If you remove your swingarm and place a long bolt through the pivot hole, you'll quickly reveal if it is crooked.

I was once instructed to use a tie-down strap to pull the axle straight, prior to tightening. It worked well for about a week and the axle made its way back sideways. I readjusted the chain and left it crooked. It didn't make it ride sideways or weird so I quit sweating about it.

2LZ- thanks I remembered reading something like that on here I just couldn't find it again. But don't worry too much it won't cause tires to wear wrong?
also any tips on checking toe in on front wheels?

Pivot hole on frame or swingarm? I assume the frame. But I try not to assume things tends to make an ass out of people. lol

The hole in the swingarm. In other words, completely remove the swingarm from the quad and then place a long bolt through the hole, which will show you just how far out of whack the welding can be. You'll see how the bolt should be perpendicular to the sides of the swingarm, but it is not.

I have had a few that were so bad the chain flew off every 10 feet or less ,very frustrating .

can I buy a better swing arm??

I think that would be a crapshoot .It has never been hard to cut and reweld them properly ,I would be afraid of getting something shipped in that is just as messed up as the one you are starting with .

I've given some thought to transplanting a quality swingarm onto my quad, like maybe from a Yamaha Blaster. Not sure how much fab work it would take, but it would be straight and it would have superior chain adjusters.

chain adjustment
 

Hello.... search ... CHAIN ADJUSTMENT... ON PAGE 2 is my post to adjust the chain... and then TIGHTEN THE BOLTS GOOD so they do not come loose... it fixes this.. spread within 1/2 inch front to back on both sides... you can use a 1 inch ratchet strap to help adjust...