# 5hp briggs backfiring



## dienam3less (Aug 9, 2007)

hi i have a 5hp briggs and stratton horizontal shaft motor. 


its not starting and when it does go to start it backfires. it was running before my sister took the gocart in to the field.  it stalled out and wouldn't start so i cleaned the mag. and the spark plug. after giving it a shot of starting fluid i got it to run. 2 days later i go to start it and it will only back fire. help me please!


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## justin3 (Apr 10, 2007)

check the flywheel key, see if its broken or out of place. Does it backfire out the muffler or carb?


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## 30yearTech (Sep 14, 2006)

Try a new spark plug, a fouling plug can make an engine backfire.


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## scrench (Dec 8, 2004)

if the spark plug dont fix it , it valve might be stuck open , pretty simple to pop the head off . and turn it over and make sure both valves are closing .


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## dienam3less (Aug 9, 2007)

i stuck a screw driver in the wire and laid it down ontop of the spark plug and the motor started to run..... should i go get a new mag.?
i have not checked the fly wheel yet but i dont think that would be the problem because of the whole screw driver... i think it is just a bad wire and when my sister was ridding in the feild it just shook the wire for its last time. and that would make since as to why every time i took the air cover off n moved the wire around to adjust the mag. it would work for a bit. btw the motor is on a manco dingo gocart.


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## dienam3less (Aug 9, 2007)

scrench said:


> if the spark plug dont fix it , it valve might be stuck open , pretty simple to pop the head off . and turn it over and make sure both valves are closing .



i already did that.. it was coved with carbon build up so i wiped it down. didnt want to brake anything but got as much off as i could.


and as for the sparkplud i took it out and laid it ontop of the motor... it is getting pleny of blue spark


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## 30yearTech (Sep 14, 2006)

dienam3less said:


> as for the sparkplud i took it out and laid it ontop of the motor... it is getting pleny of blue spark



There is your problem, the spark is supposed to be either Pink or Green!!!

Just kidding...

It's always a good idea to try a NEW spark plug, as a spark plug may seem to work alright out in the open, but they can do strange things when they operate under compression.


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## pyro_maniac69 (Aug 12, 2007)

dienam3less said:


> *i stuck a screw driver in the wire and laid it down ontop of the spark plug and the motor started to run*..... should i go get a new mag.?
> i have not checked the fly wheel yet but i dont think that would be the problem because of the whole screw driver... i think it is just a bad wire and when my sister was ridding in the feild it just shook the wire for its last time. and that would make since as to why every time i took the air cover off n moved the wire around to adjust the mag. it would work for a bit. btw the motor is on a manco dingo gocart.


something about that doesn't sound safe or right


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## 30yearTech (Sep 14, 2006)

dienam3less said:


> i stuck a screw driver in the wire and laid it down ontop of the spark plug and the motor started to run..... should i go get a new mag.?
> i have not checked the fly wheel yet but i dont think that would be the problem because of the whole screw driver... i think it is just a bad wire and when my sister was ridding in the feild it just shook the wire for its last time. and that would make since as to why every time i took the air cover off n moved the wire around to adjust the mag. it would work for a bit. btw the motor is on a manco dingo gocart.


I seemed to have overlooked this post. If it runs like this then the problem most likely is a sheared flywheel key. When the key gets sheared a little it advances the ignition timing (probable source of the backfire) the screw driver increases the the time it takes for the spark to jump the gap to the plug and then for the plug to fire (slightly retarding the timing) which would allow the engine to start. Check your flywheel key.


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## dienam3less (Aug 9, 2007)

well i changed the spark plug and changed the oil and put some restore oil in the motor. it has a lil more power to it and is now running. b-4 the oil change it was fowling out the plug and making it back fire. does anyone know the spark plug i should be useing? (just to make sure the right one is in there) and what the gap should be set to? 

i haven't run the motor up any hills yet so i dont know for sure if the new oil and restore oil is helping, but it did stop it from backfiring with no stress on the motor.


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## justin3 (Apr 10, 2007)

The engine restore should'nt keep the engine from backfiring, most likely it was just the plug that was giving your trouble. You should be using an RJ19LM or J19LM spark plug with a gap of .30. I use the restore in my snapper, it keeps the horrable oil burning smell away but it just covers up the problem.


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## dienam3less (Aug 9, 2007)

the spark plug that i had in the motor when i got it was a SE8J and the sparkplug i am useing right now is a 295 should i go out and get one of the ones listed above? what one has a hotter spark? should i go with a 2 prong? i have hurd that they burn fuel better; possibly reducing my carbon build up and add to the power?

i checked the gap on the plug that is in the engine right now it is
.038 (inches)

the plug that used to be in their had a .040 (inches) gap


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## tommyj3 (Sep 16, 2006)

Go buy a RJ19LM and set the gap at .30. The sparkplug gap to close or to wide will affect the engine timing. Make sure it's set at .30


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## dienam3less (Aug 9, 2007)

thanks i will go buy one and ill post as to how it works.. thanks everyone.. u are a big help!
should i go with a 2 prong? i have herd that they burn fuel better; possibly reducing my carbon build up and add to the power?


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## dienam3less (Aug 9, 2007)

well i got a 1 prong spark plug and it runs much better now. i havent taken it up any hill put it does go up my drive way now befor it would have trouble going down my drive way (it is almost level too) also i have a 1inch bump into my garage so i toped the cart right befor it and it went up the bump with no problem. my throttel was sticking on high to so i cleaned the area between the gas tank and motor and soaked it in some wd-40. took some oil out as well because it seemed to be a lil high (not sure if this effected the high idle randomly) but anyways the main point of this is to just say thank you guys u are all great thanks for the help!!!!!!


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