I agree with the folks who suggest listening for valve rattle a sign. If it wasn't for the tediousness of having to spend at least an hour scraping off the gasket seal gunk, I would check them as part of annual routine maintenance.
Bert- I agree with ya on making the gaskets. I do it too.
Getting to be a lost art. I keep various gasket material around, for just those occasions.
I've made a lot of gaskets, too. I keep a tiny ball-peen hammer and multi diameter leather punch tool just for making gaskets.
With regard to using valve clatter as a guide to when to adjust valves, that's good but sometimes valves recede into the seat and valve clearance decreases. They don't clatter and are more likely to lead to valve and seat damage than a loose valve.
Not much of a believer in gasket sealer, either. Sometimes it takes a ton of effort to clean those surfaces.
As previously mentioned.
If you can hear the rockers over the sound of the exhaust then the valve lash needs to be looked at.
Also if the mower is hard to pull start and sort of jerks is a sign that the valve lash is too big.
I do them every second service on most customers mowers so for most that would be every 4 years or so.
Don't mean to push in but I'm wondering if the^^^^^ above post would help my problems with my BR700 at all.?. The issue is this; it is very difficult to pull the cord, feels like there is way to much compression. So when I pull the starter rope either i have to pull it hard enough that it snaps back or I pull it out to maximum length. I've had a BR600, and another BR700 both were very easy to start. BTW it's about two months old and did it from day one. What should I look at? Thx in advance.