hellpppp vmax back firing

[paulhaworth]

hey guys my vmax is back firing on over run i have checked the air filter box and fitting and there fine and i have checked my exhaust headers and pipe and there all tight no leaks (kerker full system) help please

 

[donnelly317]

You got any jetting? Are u running K&N and full exhaust? Sounds like its running lean.. did this just come out pf the blue or after u installed exhaust? If it came out of blue.. might be a plugged up jet.. try the pea shooter / shotgun

 

[Dr.n2o]

Popping through carbs or exhaust ?

 

[paulhaworth]

exhaust i have a k n filter fitted i have checked all carbs jets and they are all the same

 

[tugla]

just started to pop all of a sudden?

 

[Dr.n2o]

Popping in the exhaust is generally a rich condition. Did you pull the plugs and eye em' up ?

 

[donnelly317]

Popping in the exhaust is generally a rich condition. Did you pull the plugs and eye em' up ?

http://en.wikipedia.org/wiki/Back-fire

Also lean condition. which generally speaking if you put full exhaust and k&n on a carburated engine you will be running lean. Running lean will cause the exhaust to have high heat. high enough where it will ignite the unburnt fuel inside your exhaust usually causes alot of popping on deceleration.

Once again was the bike running fine then all of a sudden acted up out of no where or did u install an exhaust or K&N then it started acting up?

 

[donnelly317]

or did it start after you had done this??

http://www.vmaxforum.net/showthread.php?t=24879

 

[wildweasel_pt]

http://en.wikipedia.org/wiki/Back-fire

Also lean condition. which generally speaking if you put full exhaust and k&n on a carburated engine you will be running lean. Running lean will cause the exhaust to have high heat. high enough where it will ignite the unburnt fuel inside your exhaust usually causes alot of popping on deceleration.

Once again was the bike running fine then all of a sudden acted up out of no where or did u install an exhaust or K&N then it started acting up?

I do not agree. Popping through exhaust (backfire?) means theres unburnt fuel on exhaust that is being lit up by exhaust heat (rich mixture). Usually happens when one or more cylinders are not burning (fouled plug for instance) and their mixture hits the exhaust and is ignited by the heated gases from remaining cylinders... If you are lean theres no extra fuel to burn and pop but the heat will increase in the engine, headers and exhaust (too much O2)...

 

[mr.maxx]

he says it backfiring on over run? after he shuts it off i assume??

 

[donnelly317]

I do not agree. Popping through exhaust (backfire?) means theres unburnt fuel on exhaust that is being lit up by exhaust heat (rich mixture). Usually happens when one or more cylinders are not burning (fouled plug for instance) and their mixture hits the exhaust and is ignited by the heated gases from remaining cylinders... If you are lean theres no extra fuel to burn and pop but the heat will increase in the engine, headers and exhaust (too much O2)...

Bahhumbahhumbug lol. It could be either depending on when it happens and how it sounds.

 

[Dr.n2o]

What do you mean by "over run"? When you accellerate to redline and close the throttle you would then be in a very rich condition when the motor spins down and the throttle plates are closed there is extremely high vacuum through the carb venturi. Being carburated, the engines vacuum is sucking raw fuel down into the cylinder. But before we get crazy here, if you say it happened instantly I would think you have a small piece of shit stuck somewhere in the PAJ's or something. Try the shotgun technique for starters and see if that helps out.....good luck man

 

[98Redlne]

Beginning of this season my Max was popping and backfiring at highway speeds when you eased up on the throttle (slight coasting) or on decel.

Did the peashooter and shotgun and the problem disappeared.

I tend to agree, a little piece of shit in one of the PAJs.