24 hp Briggs intek V twin that backfires continuously thru carb at cutting speeds. Checked compression, set valves, new head gaskets, brand new carb. Still backfires.
Please help with diagnosis. Engine only has 70 hours on it.
#2
Catherine
Welcome to the forum! :welcome:
I have moved your thread over to our Briggs & Stratton section.
Hopefully someone over there will have an answer.
That engine should have been under warrantee if it only had 70 hours on it.
A bit late now.
Start by pulling the plugs out one at a time.
If it only does it on one side then that is the problem and usually it will be either a sticky / leaking inlet valve
or
The diode between the two ignition coils
Check the diode by unplugging both coils from it.
Don't run the engine forr too long without the cover on the engine or you will oveheat the block.
If it backfires with either plug removed then pull the flywheel and replace the key which will most likely be broken.
70 hours? Isn't it still under warranty? Perhaps a valve is sticking, might try some top cylinder lube such as Marvel Mystery Oil per instructions on container.
Just fyi, the fix was a new camshaft. Camshaft exhaust lobe was rounded off. Must of been a poor quality cam to round off a lobe after 70 hours. Now after a new $100 cam, engine running great.
