Surging - where the engine speeds up and slows down - is caused by a lean fuel air mixture. The carburetors built after Sep 1997 were not adjustable or equipped with adjustable needle valves. Mixtures can be adjusted with replaceable jets located inside the carburetor.

If the carburetor was rebuilt correctly, there are other things to check. If the fuel tank is mounted higher than the engine, remove the fuel line from the carburetor to see if fuel flows freely. Aim the fuel into a jar to see if there is dirt or water present. Flush any debris from the end of the fuel line before reattaching.

Another check is to connect a vacuum gauge to the carburetor fuel fitting. This section of the carburetor is actually a vacuum operated fuel pump. Crank the engine to see if suction is present. If there is no suction, check the vacuum hose connection from the the crankcase. Sometimes the hose ends become cracked and vacuum is loss.

Is the fuel tank in the rear of the tractor? Assuming the fuel pump has suction, attach the vacuum gauge to the end of the fuel hose to see if the fuel line is good. sometimes cracks form in the fuel line and air is drawn in. Look for cracks or loose clams on all fuel connections. Look for dirt and debris in the fuel tank.

If the fuel lines are good, check the gaskets around the intake manifold to cylinder. A lean fuel air mixture could also be caused by worn valve guides - but is not likely on the opposed twin.

Most likely there is still some dirt in the carburetor. If the float is the plastic style and the float has warped, the fuel level in the float bowl is too low. If the person who rebuilt the carburetor used fuel to wash the parts, the carburetor could still be varnished. A carburetor spray must be used to clean the internal parts.

B & S 15 HP Mod 402707 Type 1242-01 Code 94042257

1 Short Block
1 Fly Wheel added
1 Complete Gasket Set

Send costs on these Items to: and how to pay ?

George Head
620 South Route 59
Ingleside, Illinois, 60041
E-Mail lemilyflong@yahoo.com
Ph 847-973-0054

Thank You 6/15/11

I have a Murray riding mower. When I push the brake to start it, it starts but when I release it the motor quits running. Wonder of the switch needs replaced on the brake clutch?