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17 hp Briggs on a Scotts Rider, Please Read! I need help!

ketchone

LawnSite Member
Hey,

I hope you Guru's out there can help me because I am looking for a piece of C4 and a cap to take this Mower out just for the pleasure of seeing it go. The Problem: 17 hp Briggs

Customer reports engine backfiring profusely. I ran Engine The mower started fine and immediately started backfiring through the carb. I noticed an blue flame arcing between the headgasket area and the muffler (igniting off the hot muffler)

Conclusion: blown head gasket. Fix: replaced gasket. Result: It would not restart, however lots of fuel vapor was being pushed out of the carborator intake. Making carb adjustments makes no difference. Lots of fuel vapors coming from carb. Constant flooding. What next?:blob4:
 

sdwally

LawnSite Senior Member
Location
San Diego, CA
Possible sheared flywheel key, would throw timing off. Check valves and valve clearance. Hope this helps.
 
OP
K

ketchone

LawnSite Member
Ran and backfired prior to head gasket replacement. So, you're surmising that the flywheel is spinning free or partly free resulting in mis-timing? Check this how? Yes, I am a newbie! But learning through a trial of fire!

Charles
 

sdwally

LawnSite Senior Member
Location
San Diego, CA
If the engine had a sudden impact of load the key has been known to shear. Flywheel will rotate a little bit out of posistion when this happens. Flywheel is still tight on shaft just rotate slightly out of posistion. Pull flywheel nut, check keyway alignment, if not visible then flywheel will have to be pulled.
Another problem B&S has had on occassion is that the valve seats work loose. If this happens sometime stake the seat back into place works. Of course valve seats and valve will have to be recut and lapped in. If valve seat is really loose in block, then you would be looking at a new shortblock.
 
OP
K

ketchone

LawnSite Member
Ok, starting from the begining. New Plug gapped to .035 with good spark. Compression checked and it holds. Gauged the valves and they are within tolerance. So next I will check the flywheel keyway alignment. As a point of interest when I pulled the valve cover the exhaust valve was very dirty however, the valves measure within tolerance.
 
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