B&S 15 hp on a Bolens lawn tractor

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  #1  
Old 03-29-08, 08:29 PM
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B&S 15 hp on a Bolens lawn tractor

I was given this lawn tractor and it had been sitting a while. I have changed the oil, plug, fuel filter and taken the carb apart and cleaned with carb and choke cleaner. I also replaced the fuel solenoid when I took the carb apart this was coated with fuel that had gunked up, pretty much I have cleaned what could be cleaned, replaced all the gaskets, ie the valve cover, head gasket, crankcase gasket. Pretty much tore the engine down and replaced and gaskets and rebuilt it.

Now when I try to start it up the engine backfires really bad and shoots flames out the exhaust, when trying to turn the engine over. I am at a loss for what to do next.
 
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Old 03-29-08, 09:26 PM
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did you rebuild the carb and not just cleaned it.
 
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Old 03-29-08, 10:59 PM
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Sounds to me like the exhaust valve clearance is too tight. I'd take a look and adjust the valves. That's assuming you got the timing marks aligned on the crank and cam shafts, and the flywheel key isn't sheared. When you say you rebuilt it... what exactly did you do?
 
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Old 03-29-08, 11:45 PM
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I replaced the rings, and put everything back in the same way it came out then replaced the crankcase gasket and that was it, didn't mess with the valves at all, just sprayed some carb and choke cleaner in and worked a lot of the junk that was built up off the valve stems and made sure the valves were seated right and replaced the head with a new gasket and then installed a new valve cover gasket.
 
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Old 03-30-08, 06:35 AM
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In that case the timing might be off. The timing is adjusted by having the correct distance from the flywheel. If you send me the serial number i can look up in my books what the distance should be. Right now i am thinking 0.015-0.017, but memory can be misleading sometimes.

Rob
 
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Old 03-30-08, 09:51 AM
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The coil gap shouldn't have an effect like this, and probably wasn't changed during the rebuild. It should be .010" FYI.

Did you line up timing marks on the gears in the engine? Also, you had to remove the head to get the piston out...so the valve settings were lost. You have to reset them.
 
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