Briggs 287707 B fire while running

Mower Envy · 06-12-2009, 09:12 PM

Hi All 1st timer here

I have a 14 hp B & S on a mastercraft mower .First the lovely plastic ring gear when last week .I replaced it with the aluminum one as well as new gear on starter . My bad was I never cleaned oil off the tapered shaft when returning flywheel and maybe didn't have proper torgue on bolt .Spun the key timing went out .Took it apart again ,replaced key with same B&S key cleaned all parts even tooka little light emery to the shaft ,torgued it properly to 65lbs which I believe was right .fired up the engine seemed to run great took it out on a maiden trip to cut 10 mins later it was loosing power and getting hot .once back in the shop I noticed the muffler was glowing bright orange the whole thing .Now I let it cool checked the key it spun again ! so I replaced key with a 3/16 piece of keystock .re-set flywheel etc.Replaced coil beacuse the wire melted .Set coil at .005" from flywheel .While all was apart decided to clean carb .Set carb in ultrasonic cleaner came out like new .I re -installed fuel line fuel would not stop flowing .flooded everthing started draining the tank ! Put in new float needle all is well again .Starts great,idles great sound good .soon as I excellerate it starts popping and backfiring .I can run the mower it cuts has enough power .It just keeps backfiring with a bit of a hesitation almost like a short curcit .I checked wire from coil it is good . I re-checked keyway in flywheel it never moved .Is this a carb adjustment issue .Oh I did drop a little seafoam in the tank .I'm at my witts end on this .Does anyone have any ideas I would apprieciate it .

Thanks

**octaneman** · 06-13-2009, 09:23 PM

Hi mowerenvy

When using seafoam the amount used is about 1/2 of 1 ounce into the fuel tank the engine has to be warm and then run it at full throttle to clear it , if not the engine will stall out. ( In containers remember, 1 oz for every gallon of gas !)If you added it to the crankcase you are supposed to run it for about an hour ( give or take) and then do an oil change. My guess is the seafoam is causing the backfire because it has to be run at full throttle. Burn off the seafoam ,add fresh gas, do an oil change and see what effect it has.

post back your findings.

Mower Envy · 06-13-2009, 10:39 PM

Thanks Octane man I'll give this a try and see what happens .I was thinking fresh gas could be the answer as well .

Thanks Again

06-12-2009, 09:12 PM	#1 (permalink)
Mower Envy Registered User Join Date: Jun 2009 Posts: 2 OS: Windows XP	Briggs 287707 B fire while running Hi All 1st timer here I have a 14 hp B & S on a mastercraft mower .First the lovely plastic ring gear when last week .I replaced it with the aluminum one as well as new gear on starter . My bad was I never cleaned oil off the tapered shaft when returning flywheel and maybe didn't have proper torgue on bolt .Spun the key timing went out .Took it apart again ,replaced key with same B&S key cleaned all parts even tooka little light emery to the shaft ,torgued it properly to 65lbs which I believe was right .fired up the engine seemed to run great took it out on a maiden trip to cut 10 mins later it was loosing power and getting hot .once back in the shop I noticed the muffler was glowing bright orange the whole thing .Now I let it cool checked the key it spun again ! so I replaced key with a 3/16 piece of keystock .re-set flywheel etc.Replaced coil beacuse the wire melted .Set coil at .005" from flywheel .While all was apart decided to clean carb .Set carb in ultrasonic cleaner came out like new .I re -installed fuel line fuel would not stop flowing .flooded everthing started draining the tank ! Put in new float needle all is well again .Starts great,idles great sound good .soon as I excellerate it starts popping and backfiring .I can run the mower it cuts has enough power .It just keeps backfiring with a bit of a hesitation almost like a short curcit .I checked wire from coil it is good . I re-checked keyway in flywheel it never moved .Is this a carb adjustment issue .Oh I did drop a little seafoam in the tank .I'm at my witts end on this .Does anyone have any ideas I would apprieciate it . Thanks

06-13-2009, 09:23 PM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 544 OS: WINXP	Re: Briggs 287707 B fire while running Hi mowerenvy When using seafoam the amount used is about 1/2 of 1 ounce into the fuel tank the engine has to be warm and then run it at full throttle to clear it , if not the engine will stall out. ( In containers remember, 1 oz for every gallon of gas !)If you added it to the crankcase you are supposed to run it for about an hour ( give or take) and then do an oil change. My guess is the seafoam is causing the backfire because it has to be run at full throttle. Burn off the seafoam ,add fresh gas, do an oil change and see what effect it has. post back your findings.

06-13-2009, 10:39 PM	#3 (permalink)
Mower Envy Registered User Join Date: Jun 2009 Posts: 2 OS: Windows XP	Re: Briggs 287707 B fire while running Thanks Octane man I'll give this a try and see what happens .I was thinking fresh gas could be the answer as well . Thanks Again