Removing the "pops" after installing a new exhaust system

[mfischler]

After installing the TBR exhaust along with the Power Commander and K&N, I was disappointed with all the "popping" that was happening. While a dyno-tune got rid of most of it (a multitude of "pops" between 5000 and 3500 rpms), there was still a single "pop" at around 2500 rpm during decel, and there was always a single "pop" on acceleration at any rpm. Now, this only happened if I went to 0% throttle - thus, if I was decelerating and was at 0%, I would get a "pop" around 22-2500 rpm. And if I was decelerating and at 0% throttle and then rolled on the throttle, I would get a single "pop" at no matter what rpm I was at. This has to do with the air cut-off system designed by Yamaha and is flashed into the ECU. There are also several other variables, engine temp, etc, and is all part of the emissions control system and comes into play whenever you are at 0% throttle. The "popping" is caused by un-spent fuel igniting in the exhaust after leaving the cylinder.

If you like the "popping" you need to do nothing. Some people like the momentary flames that can come out of the exhaust and I've been told that it doesn't do any harm to the bike or the exhaust.

However, I, for one, was brought up that a street vehicle that "backfires" is doing something wrong. So not only was I dealing with the loudness of the exhaust, but every time I slowed to a light - backfire. Every time I came into traffic and slowed and then accelerated - backfire. And trying to decelerate without going to 0% throttle is difficult at best.

So I did two things. I bought the P-1-X silencer from TBR which is awesome. The second thing I did also worked like a charm. No more "popping" under any circumstance! And it didn't effect the performance or longevity of the bike.

It did, however, effect the emissions control system. So if you can live with this one subtle change, go for it.

1) Raise the fuel tank.
2) Find the air cut-off hose located at the top front right of the air filter case (as you are sitting on the bike).
3) Disconnect the air cut-off hose from the air filter case exposing the male nipple on the air filter case.
4) Take a piece of multi-ply plastic (thick plastic drop cloth will work, and the corner of a plastic baggy may work as well), and press your finger into it to make a dimple.
5) Place the dimple over the male connector of the air filter case and replace the hose. The goal here is to block any air from coming or going to the case through the hose.
6) Replace the clip holding the hose in place.
7) Lower and secure the fuel tank.

That's it. The air cut-off circuit is now blocked and all your "popping" should be gone. I used thick plastic, though as I mentioned above, the corner of a plastic baggie could work - for either you need to cut to size.

Good luck!

[99vengeur]

Hmmm....I might have to try this the next time I've got some free time.

[cbzdel]

Is this what they consider the smog system?? what it does it just dump fresh air into the exhaust system to help clean it up??

[arcflash316]

so you pretty much removed the hose, placed plastic over the male side and reconnected it back together? thats all??? sounds easy, except for the tank removal... and how much was the silencer from TBR?

[PuRpl3_Dr4nK]

If it's not too much trouble could you take pics of what you did? I know it's a pain lifting up the gas tank but it would be much appreciated!

[stroke]

this mod works GREAT my exhaust has no backpops any more... and it is very simple to do the hose is an ease to find.. its actually i think the only one visible coming off the air filter box.. just unclamp, fit the plastic around the opening and reclamp.. BAM your done just like that lol... then start her up and enjoy the fruits of your labor..

[cbzdel]

would this accomplish anything by doing it to a stock bike? noticable gains or losses?

[arcflash316]

Originally Posted by PuRpl3_Dr4nK

If it's not too much trouble could you take pics of what you did? I know it's a pain lifting up the gas tank but it would be much appreciated!

I took a few minutes after work to do this mod and let me tell you it is easier than I thought.... . Get a 5mm allen wrench and a 10mm socket and wratchet.... look just below your triple clamps where your handle bar pivots and meets the frame and there are two 5mm bolts, remove them without scratching the tank.
Now remove passenger and main seats(5mm allen) including the plastic piece that allows you to raise or lower the main seat with the 10mm socket.... now remove the bolt that holds the tank down, under the seat(also 5mm) and carefully lift the tank up and wedge a small block of wood between the tank and air box to allow access to the only visible hose located on the air box (on the right side) and loosen the clamp and plug the hole with the plastic as descibed before, Reconnect the hose with the plastic in place and reassemble and like they have said, it works with very minimal popping only on deaccelleration.... so far its the cheapest and easiest mod i've done... and its effective..... give it a try and if you don't like it it easily reversable

[toekneedee]

Originally Posted by cbzdel

would this accomplish anything by doing it to a stock bike? noticable gains or losses?

I don't think this would be a good idea on a bike with stock exhaust. The additional air is most likely used to keep the catalyst at proper operating temp.
td

[arcflash316]

my ride to work this morning was much more enjoyable than I expected because I didn't have to try and control all the popping upon deaccelleration.... think I will leave the plastic in there.....my wife liked the popping because she could hear me slowing down at the stop light near our house....