Hi all this is my first post on this.

I have a GCV160 that keeps breaking the exhaust rocker arm. Its not burning any oil the valve seems to move freely. I've set the adjustment correctly. When its running it runs smooth no issues starts right up. I've checked the timing marks on the cam and the top center and that seems to be right. I would think if the valve guide was bad it would burn oil. Its only the exhaust valve that this is happing to. Any help or ideas?
Thanks
Mike