Reply With QuoteNeed to no, should yes. It will take a custom tune to fully rid the pop and it still may do it. I think of my Buell as a old American hot rod, it's crude but oh so fun
Like the title says. backfiring in deceleration. Probably lean.
Bike has: K@N...Jardine and Dobeck TFI. Do I need to re-map or get Race ECM?
2003 XB9S
Need to no, should yes. It will take a custom tune to fully rid the pop and it still may do it. I think of my Buell as a old American hot rod, it's crude but oh so fun
you should tune it, but the decel pop is normal
You need some cake!! That will take care of the popping for sure. If that doesnt work for ya and you Need a little less sugar with some nice crust cherry pie is the next best thing.
have an '03 9S...factory installed race ecm, pro-series exhaust, K&N filter...she always pops when rolling off the throttle
If you "tune" it not to pop, then you are actually de-tuning.
I dont know what I would do without decel pop. It is part of our bikes character. I get pissed when it doesnt do it, which isnt too often. :D
This isn't specifically about Buells, but it doesn't matter what bike it is it will happen. Then pair valve mentioned is not something that is on a Buell and is only refering to other engines.
Deceleration Backfire is caused by fuel burning in the exhaust manifold or header.
No ifs ands or buts, that’s what causes it. But the bigger question is how does gas get there in the first place, and that’s a bit more complicated. Generally, there are a variety of ways it gets there, and a variety of things that can make the backfiring worse. But there’s a kicker, and something you should understand before we go any farther:
A motor in perfect tune will exhibit deceleration backfiring.
Therefore, just because your motor is banging it up, doesn’t mean there’s anything wrong. And consequently:
Getting rid of the noise means de-tuning your motor.
Yup. If you’ve just have to eliminate that popping, you’ll have to accept the fact that your motor is going to be forced to run rich to do it, and that isn’t necessarily a good thing. So lets talk about what causes the problem.
Ok, so you’re riding along at some given rpm, and suddenly you decide to decelerate, and you reduce the amount of throttle. This causes an “overrun” – that is, the motors rpm is turning faster than the fuel provided can support, so the motor begins to spool down. This causes a couple of things to happen.
First, when you close the throttle, you are also closing the throttle plates. This reduces the air and fuel flowing into the motor, and increases the vacuum (lowers the pressure). This results in less air and fuel in the cylinder during the power stroke, which in turn results in a lower pressure in the combustion chamber. Remember I said earlier, that the A/F mix burns faster in proportion to the pressure applied? Well, when we reduce pressure this way, the mix burns slower. This results in two things happening.
1. The lower burning fuel generates less heat, and the cooling effect of the non-burning fuel tends to “quench” the flame front, or slow it down even further. Because the mix is burning much slower, the exhaust valve can open before all the fuel is consumed, and the unburnt fuel is ejected into the exhaust.
2. The engine designers, in order to promote smoother idling and better combustion, retard the spark when the throttle is shut, and this results in the mix being lit later.
So, now we end up with unburnt fuel in the exhaust, and burning fuel being ejected into the exhaust, and bang! Backfire. In addition, Honda has added a device called a “programmed air injection valve” (Pair Valve) that actually injects some fresh air into the exhaust to help this process along – since fully burning the fuel results in cleaner exhaust. So the backfiring is not only a normal part of the engines operation, it’s also intentionally amplified by Honda! Of course, normally, that massive bazooka pipe Honda hangs on your bike hides most of the noise, but it’s there, even when you can’t hear it.
So the bottom line, is: That backfiring is perfectly normal and expected. If you’ve just got get rid of it, that’s up to you. You’re entitled to set your motor up the way you want, and your goals are your goals. But don’t refer to it as “fixing” the popping. Rather, the correct way to think of it is “de-tuning a bit to get rid of the popping”.
There are a few ways you can do this.
First, use the stock pipe. It will hide the sound, by absorbing it into mass, and masking it with the larger baffle space. Second, you can add more fuel during deceleration. This has the effect of raising the chamber pressure slightly, which burns a little more before the exhaust valve opens. Lastly, you can remove the Pair valve, which reduces the amount of available oxygen in the pipe to burn the unburnt fuel.
I remember the day i drove off with my brand new 2010 XB it had a decel pop on it in 100% stock condition. Its just the nature of our bikes IMO.
I kinda like the decel pop...doesn't mean your lean. I love when I'm hard on it and everybody knows I'm comin, then when I let off it goes POP, POP, POP...they now know I'm there! LOL
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