Cb500t won't start and keeps backfiring out the carbs

[Chenz]

I recently picked up a cb500t that wasn't running and have not been able to get it to start. It seems like the timing is off because it keeps popping and back firing when I try to start it. I set the timing with a test lite how it shows in the book but the weird part about it is to get it all set so the test light comes on at the right mark I had to advance it as far as it would go. I've checks it a few time and it lines up the same every time. Not sure if I'm doing something wrong or if it's something else. It won't even start up for a second with starter fluid.
Here's everything else I'm adjusted:
- Set the plug gap
- Set points gap
- Set timing
- Set valve lash
- Checked for spark
- Charged the battery
- Cleaned the carbs
- Right cylinder has 130psi of compression
- Left cylinder has 120psi of compression
- Changed the oil

 

[Bert Jan]

Switch the coil leads from left to right. You have the plug wires on the wrong spark plug