I need help finding out thread size on bolt?

I have a 1994 Yamaha YZ 125 dirtbike, and the threads are stripped out on the crank where there flywheel goes. The nut that holds the flywheel back on the crankshaft has really messed up threads. I want to use a tap and die set to restore the threads, but I don't have a kit, so I will buy one die to fix it. I need to know what size it is though. Should be the same for all YZ 125's according to bikebandit.com



"3BM nut" is what bike bandit calls it.



What size die do i need??I need help finding out thread size on bolt?
Print out the US and Metric Thread Gauge

http://www.boltdepot.com/Fastener-Inform鈥?/a>

Put it up to the threads on the crankshaft.

Measure the diameter of the crankshaft where the threads are.

The tap %26amp; die size will read like this 12 x1.5

The very large number (like 38) will be the size of the wrench the fastener uses to tighten %26amp; loosen it.I need help finding out thread size on bolt?
Try a thread file (metric) instead:



http://www.webbikeworld.com/motorcycle-t鈥?/a>I need help finding out thread size on bolt?
are you sure thats not 38 mm