B.S. Engine 128m02-1612-f1-12041958 DOM Apr 2012
190 cc Platinum 7.25 on a 22" walk behind mower
I've worked on a lot of engines, but this ones got me stumped!
This engine has a very weak spark when started with starter rope. With a neon tester connected to the spark plug, it barely glow while pulling the rope starter. If you pull it moderately, there is no spark at all. only at the fastest pull will it generate a pulse.
Compression at the spark plug is less than 4 lbs,(It has a compression release built in to the cam wheel), so it' easy to spin over,but the engine will not start with pull rope.
When starter rope is removed and flywheel exposed, using a drill and socket on the flywheel to generate a higher starting speed, the engine will start and run well but only after higher rpm,s than can be generated with pull rope. The spark is great while it is running. Engine runs very well after it is started.
Have serviced carburetor ( that was clean to start with but cleaned it any way), checked valves and lashing, changed out spark plug, changed out Magnetron (coil pack) and set at 10 thousandths inch. Checked éeady start system ( auto choke mechanism with thermostat on exhaust that interfaces with auto choke), checked all carburetor linkage and governor. These are all functioning correctly.
I suspected a problem with the magnetron coil pack, but Engine runs great with new and old magnetron, once you get it started. Also checked that the kill switch connection is not grounded and it works the same with it connected or disconnected from the Magnetron.
Starting speed of engine is only factor that changes. Once the starting speed is increased, the engine will start and run great, but pull with all my might, I cannot get enough speed to start the engine with the pull rope, let alone someone not as strong or big as I.
I have tried to prime the start with a little gasoline in the carburetor, but it just fouls the spark plug.
I have also pulled the plug after a lot of unproductive pulls with the starter to find the plug moist and fouled with gasoline.
This has been a real problem. What can be done to fix this issue?
Briggs and Stratton have been of no help, only telling me that it take one of their specialist to adjust the ready start system.
One last observance, it take 4-5 seconds of turning with the drill before the first pop of the engine, followed by a couple more hit and misses, then it starts
CONCLUSION:
the magnetron will produce a good spark, but only at rpm,s above about 600-700
The extremely low compression must be ok becuase it runs great once it's started.
If anyone has had experience correcting these symptoms, I would be very thankful for any advice.
190 cc Platinum 7.25 on a 22" walk behind mower
I've worked on a lot of engines, but this ones got me stumped!
This engine has a very weak spark when started with starter rope. With a neon tester connected to the spark plug, it barely glow while pulling the rope starter. If you pull it moderately, there is no spark at all. only at the fastest pull will it generate a pulse.
Compression at the spark plug is less than 4 lbs,(It has a compression release built in to the cam wheel), so it' easy to spin over,but the engine will not start with pull rope.
When starter rope is removed and flywheel exposed, using a drill and socket on the flywheel to generate a higher starting speed, the engine will start and run well but only after higher rpm,s than can be generated with pull rope. The spark is great while it is running. Engine runs very well after it is started.
Have serviced carburetor ( that was clean to start with but cleaned it any way), checked valves and lashing, changed out spark plug, changed out Magnetron (coil pack) and set at 10 thousandths inch. Checked éeady start system ( auto choke mechanism with thermostat on exhaust that interfaces with auto choke), checked all carburetor linkage and governor. These are all functioning correctly.
I suspected a problem with the magnetron coil pack, but Engine runs great with new and old magnetron, once you get it started. Also checked that the kill switch connection is not grounded and it works the same with it connected or disconnected from the Magnetron.
Starting speed of engine is only factor that changes. Once the starting speed is increased, the engine will start and run great, but pull with all my might, I cannot get enough speed to start the engine with the pull rope, let alone someone not as strong or big as I.
I have tried to prime the start with a little gasoline in the carburetor, but it just fouls the spark plug.
I have also pulled the plug after a lot of unproductive pulls with the starter to find the plug moist and fouled with gasoline.
This has been a real problem. What can be done to fix this issue?
Briggs and Stratton have been of no help, only telling me that it take one of their specialist to adjust the ready start system.
One last observance, it take 4-5 seconds of turning with the drill before the first pop of the engine, followed by a couple more hit and misses, then it starts
CONCLUSION:
the magnetron will produce a good spark, but only at rpm,s above about 600-700
The extremely low compression must be ok becuase it runs great once it's started.
If anyone has had experience correcting these symptoms, I would be very thankful for any advice.