# Help 05 750 sputtering and backfire



## FL.cowboy (Oct 15, 2010)

05 750. Starts up and when you give it gas it revs up then down and the back cylinder is sputtering and backfires. What could be causing this 

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## NMKawierider (Apr 11, 2009)

FL.cowboy said:


> 05 750. Starts up and when you give it gas it revs up then down and the back cylinder is sputtering and backfires. What could be causing this
> 
> Sent from my PG86100 using Tapatalk


Tight valves,cracked intake boot,water in the bowl, low fuel supply,weak spark, blown head gasket, plugged passages in carb,...


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## FL.cowboy (Oct 15, 2010)

If it helps we pulled the rear plug boot and it runs the same but no back fire 

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## FL.cowboy (Oct 15, 2010)

here is the story. we changed the oil, and spark plugs with ngk cr7e plugs. and now its sputtering and back firing on the back cylinder. we took the carbs off and are going to clean them up but i do not think that was it. any ideas?


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## NMKawierider (Apr 11, 2009)

FL.cowboy said:


> here is the story. we changed the oil, and spark plugs with ngk cr7e plugs. and now its sputtering and back firing on the back cylinder. we took the carbs off and are going to clean them up but i do not think that was it. any ideas?


Might just be a bad plug. Put an old one back in the rear cylinder and see.


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## FL.cowboy (Oct 15, 2010)

tried that and it still ran the same...


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## Waddaman (Oct 3, 2010)

You just said in another thread you just got a Big Gun. Did you put a tuner on it as well?


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## FL.cowboy (Oct 15, 2010)

This is a diff bike. Mine with a big gun is an 09. The bike with the problem is an 05

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## FL.cowboy (Oct 15, 2010)

Any way to tell if the spark plug boot is good or the wire. I pulled the plug and turned it over with it still in the boot and I saw a spark. But no telling if its enough or anything

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## tony1j (Mar 11, 2011)

Had a similar issue with mine not long ago, it was a bad vent line on my carb. mine is snorkled so it runs up into my pod yet somehow it still ended up clogged.


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## bfbrian (Dec 20, 2010)

I have a 06 750 and it was doing the same thing. Mine had a split carb boot. Does it get better if you choke the carbs a little? This will richen up the fuel mixture and it will run better. Check to see if the carb boot is split.


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## FL.cowboy (Oct 15, 2010)

check thanks guys. i am going to work on it in 30 minns ill keep everyone updated


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## KMKjr (Jan 9, 2009)

Mine did the same and was just dirty carbs. Had to pour Seafoam into them and let sit and soak.


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## FL.cowboy (Oct 15, 2010)

i think we have located a prob. it seems like its dumping to much fuel in the rear carb


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## KidRock (Nov 19, 2010)

Float stuck?


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