Yamaha phazer MBRP exhaust backfire.

[Devin yamaha man]

Hello guys last winter i installed a mbrp pipe for my 2007 phazer fx and when i use the engine breaking rolling up to a stop sign it makes a snapping noise.......and at night i see a small blue flame shoot from the pipe, is this good or bad??

heres a vid of what the issue looks like
https://www.youtube.com/watch?v=FxS3PMDOWP4

 

[maim]

usually indicates a lean condition when a 4 stroke does that.

 

[Devin yamaha man]

what do you mean by lean condition?

 

[Devin yamaha man]

would it be too much fuel or air.....or not enough of one or the other, or not enough pressure in the pipe itself?

 

[Devin yamaha man]

heres a vid also of what this "backfire" looks like during the night, everything is stock on it besides the pipe which was welded right where the stock muffler sits.

https://www.youtube.com/watch?v=FxS3PMDOWP4

 

[maim]

Most likely a lean condition from better exh flow. A dirty trick so you do not need a programer is to run 1heat range colder plug and close the gap ten thou. Had to do that to a truck before and it also works on motorcycles and sleds.

 

[Devin yamaha man]

Can you better explain this method of fixing it?

 

[maim]

I was told this is how they jet bikes and cars with mods overseas. They typically go one heat range colder than the stock spark plug and close the electrode gap 10 thou less than the gap it came with. Running an iridium plug in the stock heat range also let's the engine run richer than stock jetting.

 

[Devin yamaha man]

So, if I keep running the sled like this will it damage anything, or is it fine backfiring the odd time when the sleds running hot?

 

[maim]

should be ok if it is just pop'ing . if it is actually backfiring , it needs to be looked after.

 

[Devin yamaha man]

Hmm, well it's sounds purely from the pipe, I just don't know where the blue flame gets generated in an all stock sled besides the can

 

[kirkswim]

It is a lean condition. What is happening is there is not enough fuel for combustion so the unburned fuel is pushed into the exhaust system. this unhurt fuel and O2 sits in the exhaust until there is enough fuel or the air to fuel ratio is enough for combustion. With the right temp/heat/flame from an exhaust stroke the unburied gases in the exhaust ignite and cause the blue flame that you see. Like maim said quick and dirty fix to try is go to a colder plug CR10EKB, or the half step is CR9EIX as the iridium will run slightly colder. The spark plug also helps to control cylinder temps. I would try the colder plug first and if it makes it better then use a programer if you wish. If it does not work it was less than $20 to try and you would know that a programer is needed. It could also be that your cdi/computer is doing something weird and not telling the injectors to put enough fuel in, or you could have and injector that is partially plugged/not fuelling enough.

Just some thoughts to try.

 

[Devin yamaha man]

thankyou very much, it ran perfect with the stock exaust....since the mbrp it started doing a backfire fairly rare hope its not terrible and not blow up the motor.....