22 hp vtwin ohv B&S. I pulled the valve cover and found both pushrods bent. Replaced them and hand turned the flywheel to check valve operation and bent the exhaust rod again. Valves can be depressed with my thumb and don't appear to be sticking. Removed the head and there are no signs of valves contacting the piston due to a timing issue. Any ideas?

Terry, August 2010

If the valve guide has backed out of the head toward the spring it will keep the rocker from compressing the spring all the way causing excessive pressure on the push rod.

Terry, August 2010

Check valve guides to ensure they are fully seated and haven't shifted which allows too much play/sloppiness in valve train.

Terry, August 2010