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B&S 15.5hp ohv i/c engine backfiring when trying to start

#1

M

MyBallsHurt

So awhile ago the mower wouldn't start and had been having some problems a few weeks before and i just sprayed carb cleaner, now the engine will not start and backfires loudly. So i thought i should do a value adjustment, everything looked good inside, did the adjustment at 004 on both. It will still not start but does not backfire as loud or as often.


#2

G

gregjo1948

MyBallsHurt said:
So awhile ago the mower wouldn't start and had been having some problems a few weeks before and i just sprayed carb cleaner, now the engine will not start and backfires loudly. So i thought i should do a value adjustment, everything looked good inside, did the adjustment at 004 on both. It will still not start but does not backfire as loud or as often.
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It does sound like a valve problem. Check the adjustment on the exhaust. There is a compression release that causes the exhaust valve to be partially open. Rotate the engine and you can see the intake and exhaust both open at the same time. gregjo1948


#3

I

ILENGINE

I would also make sure the flywheel key isn't sheared or offset. Strange things can happen sometimes.


#4

C

choogie62557

Your cam lobe may be worn off. Check lifter movement.


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