B&S 22hp Intek twin valve, bent push rod

I have a yard machine with a B&S 22hp (family YBSXS-7242BF) Intek Twin, First time out Was running fine then backfired, now running on one cylinder, removed overhead valve cover to find a bent pushrod ( right side cylinder, bottom rod). What might have caused this? and what is the gap when putting back together and anything else I should know/do

It can happen due to various reasons. Some times there is no explanation. first make sure the valve guide hasn't backed out and allowed the rocker arm to hit it. That will bend a push rod every time. If the guide has drifted out, you will need to replace the head, because even though you can press it back in place, it will not stay there, and migrate again.

The valve clearance should be .005-.007

Cruizer.. most things have reasons, but I agree with ILENGINE that sometimes there seems to be no reason. Heat is a major culprit, but unless you put on an oil cooler you cannot improve the marginal cooling . You can put on a sump temp gauge for less than $50 which will give you INDIRECT indication of head temperature. My Intek craftsman 24 runs oil temp near 300 F doing heavy work at 85F ambient. Anyway one cause of bent pushrod can be heavy deposits in the valve guides which can freeze the valve closed. Another is lack of valve adjustment ( I wish I had bought a hydraulic lifter engine). And as ILENGINE knows valve guides can loosen. Search this forum for extensive discussions.

Thanks for the replys, I will check the valve guide