woodruff key

[tumbler440Ex]

i having a problem when i put my trx 250r 86 together had to replace case halve and when i got it all together i bought a new key the half moon one that goes on the rotter by the magnetto the key goes on the crank shaft but everytime i get it started let it worm up i give it half throttle she bogs out then i let off it and give it full and then the key brakes i bought like 4 of them and all them broke anyone would know what would be wrong
please help me out asp please:confused:

[UglyMotha™]

i do know if there not the right size and a little under they will get sheared right in half but if you getting the right ones i have no clue what else could be causeing it:confused:

[tumbler440Ex]

well i had the wrong nut at first for the rotor but i had the right key after that broke a guy made me a few of them the right size almost prolly not right on the right shape but i took it to the best macanic's around this eara and order the right nut and 4 keys haha so hopefu;ly i find out whats causing it but i would like ot find out befor they get the keys lol try to be a bit smater tham them ahaha