andrewslarge
Well-Known Member
I didn’t see where you removed the flywheel to inspect the key?
I think you are working on spark at the correct time?
I think you are working on spark at the correct time?
B&S 550 EX stopped - won't restart
- Thread starter BobbyC777
- Start date
Sorry - I somehow missed your earlier reply - just went back & found it. I removed the flywheel nut so I could see the key but I have not removed the flywheel. I have good compression. I've tried a couple of coils. I have not hit anything to knock timing off. When it died initially, I was able to restart it twice but it only ran for about 20 seconds each time. If the timing had gone off I don't think it would have started at all. Ether (carb off) got it running twice - but only twice. Kill switch wire removed from coil. Spark is OK when grounded to block.
I have a few things left to try - remove flywheel to check spark timing (key); new gas (what I was using was very new but can't vouch for quality). Remove head.
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Take out the
Stop. No head removal. Take out the spark plug and insert screw driver blade. Apply pressure to the driver against piston.Turn engine over by hand til the blade is pushed out the maximum it can go befire it starts to retreat with the piston going down. This is one of two top dead centers, either at the end of the exhaust stroke or the beginning of the power stroke. In either case look at the magnet on the flywheel in relation to the coil as the crank turns in the operation direction. It should be well toward the end of the magnet as the induced magnetic field in the coil begins to collapse. In either case the plug will spark twice for 4 piston cycles up and down, up and down as this is a wasted spark ignition. Only one will be timed correctly at close to the end of the compression stroke where it does any good. There is always a bit of advance in the spark to account for flame propagation as the fuel fires to extract as much energy from the burning fuel as the piston passes top dead center. All things being equal you can be a few degrees off from the proper spark timing and still run just not as well or optimally.
Great idea - will do ! Thanks!
I am going to be out of town for several days but I will get back on this upon my return. I will certainly post what happens going forward.
One more thought ... since the intake valve is only open about 25% of the time, I wonder if my ether spray was not making it to the combustion chamber? I can't remember if I ever tried it directly into the spark plug hole, then quickly replaced the plug & tried to start it. Things are all a blur.
Thanks for all your help!
Bob
One more thought ... since the intake valve is only open about 25% of the time, I wonder if my ether spray was not making it to the combustion chamber? I can't remember if I ever tried it directly into the spark plug hole, then quickly replaced the plug & tried to start it. Things are all a blur.
Thanks for all your help!
Bob
A few drops of gas thru the plug hole has always been my go to.
Carb probably needs rebuilt.
Should test for spark in low light or lights off conditions. Easier to see the spark color and intensity.
Again test with an open gap spark tester. Best tool for checking spark.
OR a simple 12 volt test light grounded to the engine block. You can move the pointed tip away from the plug boot which stresses out the ignition coil.
Most good new push mower coils can barely jump a 1/4" gap.
Buddies old Corolla jumped a solid 2 inch gap. Nearly maxed out the tester below. Jumped to the middle of the 4|0 mark with a purpose.
Should test for spark in low light or lights off conditions. Easier to see the spark color and intensity.
Again test with an open gap spark tester. Best tool for checking spark.
OR a simple 12 volt test light grounded to the engine block. You can move the pointed tip away from the plug boot which stresses out the ignition coil.
Most good new push mower coils can barely jump a 1/4" gap.
Buddies old Corolla jumped a solid 2 inch gap. Nearly maxed out the tester below. Jumped to the middle of the 4|0 mark with a purpose.
I'm back - as promised! I hate throwing parts at things but many people encouraged me to buy a new carburetor. I was reluctant as starter fluid wouldn't get it to run. But I sent Jeff Bezos $14 and he delivered a new carb to my door.
(Rakiyada 799584). I had to clean up one of the throttle pieces just a little with a Dremel as it was hanging up on another piece. I was not optimistic but it started up on the first pull! Maybe I should mow the lawn before sending this but I'll tempt fate and declare victory. Thanks for your support and suggestions!
And if anyone has any theories as to why starter fluid spray wouldn't get it to run for a few seconds, I'd love to hear them!
Bob
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