82 kx80 firing problem. Need help

[brokekx80]

I recently bought a 82 kx80.. The problem Im having,is tat it will only fire every now and then...
I put a new coil on it,but it does te same thing..

It will fire a few times in a row,and then wont fire a few times.

I dont know what to ty next,I dont want to just throw parts at it.I need some advice on where to look next..

There is another black box next to the coil,does this have anything to do with it?
Any help would be awesome...Thanks

 

[jason33]

take the magneto electrical side of bike- off and check the (woodruff key),see if its broken,it will fire oddly,and out of time so it will never start-lol