The church bought an almost new, very lightly used consumer grade "bolens" lawn tractor a month or so back. It looked to be in VERY nice shape, ran well, and the price was right. On Friday I got a call from the older gentleman who does the lawn mowing, saying the tractor had lost power and he just barely got it back in the shed. It has a B&S "Powermore" 500cc 13.5 HP OHV single engine. When I got there this afternoon to check it out it would not turn over. When I pulled the plug it cranked OK but even then the battery voltage dropped to about
9 volts. I took the battery to the battery shop to have it checked and the guy said it was a 135CCA battery, usually used on 5HP tractors, and only tested at about 95cca. I bought a new "east penn" 350cca battery for $70 including tax and gave it a try. Still didn't crank, (I eventually did get it to make one full revolution and the engine started) but the voltage didn't drop as far. When it started it hardly had any power at all so I popped off the rocker cover to check valve clearance and found the one rocker stud (the bottom one) backed out almost 1/4" (and the thead is only about 7/16 inch long) and the adjuster nut was loose on the stud.
I cleaned it up and Loc-Tited the stud into the head, re-adjusted the clearance and tightened the little Torx jam-screw in the end of the adjuster nut and it spun over perfectly. Buttoned it up and it's running like new. Those darn engines are so noisy you can't even begin to hear a loose valve adjustment.
Pretty crappy assembly to have the rocker stud come loose before the muffler is even discoloured!!