Lean
Check for airleaks. Your main jet may be too small, it may be partially blocked. Were you using the same gas as usual or was it more than a couple of months old? Had you been running the thing full open throttle where you usually do forest & hadn’t had problems with it being lean?
Small possibility of the ignition timing being too advanced, but that would leave the plug covered in Aluminium & a pit in the top of the piston.
As for the waterpump the simple way to check it is take the cover off it, kick it over & see if it turns. Unlikely to fail.
Check for airleaks. Your main jet may be too small, it may be partially blocked. Were you using the same gas as usual or was it more than a couple of months old? Had you been running the thing full open throttle where you usually do forest & hadn’t had problems with it being lean?
Small possibility of the ignition timing being too advanced, but that would leave the plug covered in Aluminium & a pit in the top of the piston.
As for the waterpump the simple way to check it is take the cover off it, kick it over & see if it turns. Unlikely to fail.
