Blaster nut size?

[Jpass]

Does anyone know what size the nut is that holds the ride plate on a '93 B1? The bolt is just spinning and when I look in the rear compartment I can see the nut and bolt spinning. I've tried numerous size box wrenches on it (10mm-13mm) with no luck. It's very hard to reach and was wondering if anyone knew the correct size of the nut?

No idea how I am going to get this off.

Suggestions?

 

[Jpass]

Anyone?

 

[TOBTEK]

yamaha uses 8x125 thread pitch with a 12mm head. im assuming it also has a 12mm nut. pretty sure Yamaha uses 8,10,12 & 14mm head sizes. no 13's like the older Kawi's.

If that doesnt work.....grab the Vise-Grips

 

[Jpass]

It was a 12mm. Had to use an open end wrech while my neighbor hit it with the air ratchet after it soaked in some penetrating oil. It was ridiculously corroded. New hardware is ready to go.