Author Topic: Popping backfiring during heavy acceleration  (Read 234 times)

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Offline DC Concours

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Popping backfiring during heavy acceleration
« on: September 23, 2017, 02:20:50 am »

Quick question...


Yesterday when I was accelerating at high rpms (while my gas was low) my bike was producing some loud popping/backfiring. Why and how did that happen? Never happened before. Is it time for more carb work?


I did realize soon after that I was running out of gas so I switched to reserve and all seemed fine.


Offline Mettler1

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Re: Popping backfiring during heavy acceleration
« Reply #1 on: September 23, 2017, 03:21:30 am »
   Nice fix!! And you did it all by yourself!! :beerchug:
'94 Concours 115,000 miles-- 7th gear,2MM,KB fork brace,Over flowtubes,Stick coils,Tcro shifter,GPS,SiSF'sTorque cams,SPOOKFAK,block off plates, SS brake & clutch lines,KB risers, FENDA EXTENDA, emulators, SiSF carb Spa, Delkevic exhaust, Murphs' knee savers +grips, etc

Offline MAN OF BLUES

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Re: Popping backfiring during heavy acceleration
« Reply #2 on: September 23, 2017, 04:22:54 am »
Dump in a full bottle of IsoHeet, you got some water in there and when you got lo on fuel, it shook it up and was creating that...
Might wanna set it on the centerstand overnight tho, before adding the IsoHeet, and drain the floarbowls int a glass container to do a quick check...

But popping and bacfires when accelerating at high rpms is a telltale sign of water for sure...

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline DC Concours

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Re: Popping backfiring during heavy acceleration
« Reply #3 on: September 23, 2017, 09:03:50 pm »
Thanks MOB. I knew there was more to this than just a fluke. I will do as you recommend. Already bought the isoheet last evening.

Just because I am curious... what causes the actual pop? How does diluted fuel do that?

Offline MAN OF BLUES

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Re: Popping backfiring during heavy acceleration
« Reply #4 on: September 23, 2017, 10:34:41 pm »
Thanks MOB. I knew there was more to this than just a fluke. I will do as you recommend. Already bought the isoheet last evening.

Just because I am curious... what causes the actual pop? How does diluted fuel do that?

As I noted, do a pre drain of the bowls, to get that water out.
Then add the IsoHeet.. and ride at least a hunderd or so miles, more is better, just figure on a four hour ride, 2 hours out, 2 hours back... burning as much as possible.. the isoheet binds the water to the fuel on a molecular level, it doesn't remove it, it binds it so it can be burned...
Pouring the additive into a tank, and letting it sit, does nothing, and actually can make it worse, as if the tank isn't full, the isomer qualities of the chemicalnreaction will continue to absorb moisture, and when let set, it will eventually come out of suspension, and go to the tank bottom once again... and make future attempts at binding it with further additions futile and difficult, end result is draining and cleaning the tank dry, and starting from scratch again...

As for the popping and backfiring, its all a product of water globules trying to make their way thru the emulsion tubes and jets in the carbs, and water compared to fuel, is very blocking in that respect.. so blocking and unblocking those small holes, creates an imbalance in steady state fuel flow, sometimes more fuel, sometimes less, all on the same intake stroke.. this enriches and starves the combustion process, and when the engine is trying tonaccelerate changes the combustion properties to a point where oxygen and vapors start igniting in an uncontrolled manner... thus, bang, pop, etc.

Once stabilization has been done, and the fuel is consistant, and not containing water globs, it ceases to buck and snort, and pop, and bang... and will run smoothly, via the properties that constant velocity carbs were designed for...

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline DC Concours

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Re: Popping backfiring during heavy acceleration
« Reply #5 on: September 24, 2017, 12:16:40 am »
Thanks mob. I always learn something with you.