reasons for bike to pop on decel

[gage]

the octane has nothing to do with your air/fuel mixture... if your bike has an 02 sensor (not running a DP ECU), then try getting a fatduc to richen your mixture.

Octane does impact air/fuel ratio... Here is a pretty basic description with the formulas etc... http://en.wikipedia.org/wiki/Air-fuel_ratio

i didn't realize your bike was closed loop... good luck!

[ducpainter]

popping on decel has nothing to do with octane.

It can be caused by a lean mixture...

an airleak in the exhaust,

or a very rich mixture that explodes in the hot exhaust and shoots flames about 3 feet long.

The last one is cool.

[gage]

popping on decel has nothing to do with octane.

It can be caused by a lean mixture...

an airleak in the exhaust,

or a very rich mixture that explodes in the hot exhaust and shoots flames about 3 feet long.

The last one is cool.

I still disagree because AFR is impacted by octane... However, the key distinction and one that I had started to overlook -is popping on decel - if the fault were octane related it would be evidenced by knocking or pinging which happen under load.

[ducpainter]

I still disagree because AFR is impacted by octane... <snip>

I need documentation on that.

[gage]

Here is a pretty basic description with the formulas etc... http://en.wikipedia.org/wiki/Air-fuel_ratio

see above link.

-The professor

[OT]

but it's never been a problem before so I can't imagine it's a fuel/air mixture.

Check to see if the bolts holding the exhaust headers onto the cylinder heads have come loose.  My top header bolts get a bit loose about once a year....I know it's happened 'cause the bike makes a nice loud pop on decel once in a while....tighten the bolts and the pop goes away

[ducpainter]

see above link.

-The professor

This article does not cite any references or sources.

not biting.

[LowThudd]

Octane does impact air/fuel ratio... Here is a pretty basic description with the formulas etc... http://en.wikipedia.org/wiki/Air-fuel_ratio

i didn't realize your bike was closed loop... good luck!

I disagree entirely that octane is a pure regulator of A/F ratio, and the article did not state that. For example, ethanol has a much higher octaune than "Pure" gasoline, however it's BTU content is much lower. Therefore, an alcohol powered vehicle must run much richer in order to produce much power. And the C/R or intake PSI must be dramatically increased to take advantage of the higher octane. I think you are exagerating the effect that a few octane points(that are mostly there from ethanol) can have on the "Effective" AFR.

[Howie]

Wiki is almost correct on the octane/air fuel ratio issue.  It all depends on how the octane is built.  In the past, with oxygenated fuels (EPA type, not the race type) and the absence of lead to build octane, MTBE and alcohol were often used to raise octane level, thereby leaning the mixture.  I have no idea if lead had any effect on mixture.

popping on decel has nothing to do with octane.

It can be caused by a lean mixture...

an airleak in the exhaust,

or a very rich mixture that explodes in the hot exhaust and shoots flames about 3 feet long.

The last one is cool.

Pay attention to what Nate wrote.  What you hear  is an after burn of unburnt fuel in the exhaust.  Introduced air, excessive hydrocarbons and from running too lean or too rich can cause this problem.  

[muskrat]

no open air box.
have DP ECU, full Termis on bike too.

Will check plugs later today.

[muskrat]

found the leak.  the mid pipe was the cause, not saying what part