My 22 hp Briggs and Stratton engine is running rough at high rpm. I checked the spark plugs and one of them is white. I changed the plugs and it still doesn't run properly. The new plug was also turning white. Do I have a head gasket problem? I have checked both the bolts on the intake and on the cylinder head and none were loose. Could it sill be the gasket or should I be looking at something else?

Dave, August 2009

I assume the mower is a twin cylinder,where one spark plug is operating showing a straw colour electrod and the other electrod is white, which we will call it no. 1
Possible faults.
Inlet manifold gasket loose or needs changing.
Insufficient petrol going to no.1
Compression low on no.1 could be piston ring or valve
Note. you can buy piston ring sealer from a car part shop.
Check spark plug is correct type and gap.
Air pressure test with no.1 on compression stroke ie, both valves closed, a gauge is fitted in plug hole.
Head gasket maybe about to blow around no.1
Always check the simple things first.

Will the off roader, August 2009

are you using the correct mix? Sounds like it is running lean

Tony, August 2009

Check the inlet manifold gaskets for leaks.

John, August 2009