2006 Suzuki Boulevard C90T Back fire

[texrider]

Sounds like all's well that ends well here.

The air injection system is usually there to promote afterburning of exhaust gasses, once they have exited the cylinders. Air injection also helps maintain high temperatures in the catalytic converters that are inside many stock exhaust systems, as they must be hot to work effectively...

[fotodude1]

I have an 05 90T with Vance and Hines pipes. It backfires when I let off the throttle. There is a possible fix out there and some may be able to help with this. That is a Power Commander. I haven't purchased one yet but just got back from a rally where power commander was set up and talked to the guys there. I know they sell these things but they say they really work. We discussed this in a forum in the mechanics corner several months ago.

[AZRyder]

Originally Posted by Dan Janousek

I purchased a brand new C90T April 26, 2006. It back fires when I let off the throttle. I have 540 miles on it. It is completle showroom stock with no after market air breathers or pipes. It is back in the dealers shop at this time for the second time right now for this problem. The dealer keeps telling me that there is nothing they can do about it as the timing is preset and cant be adjusted,and that this is characteristic of the C90T. I cant belive that Suzuki built this bike to back fire but thats what the dealer is telling me. I was just wondering if anyone has had this problem and if you solved it how did you solve it. At this point im very un happy as i spent $12000.oo plus on this bike and it back fires and all im being told is thats just the way it is and I'll just have to live with it.

How often does it backfire? Mine does it every so often on decelleration. I've also found that using the lower (87) octane gas helps as well. Mine runs really lean. The dealer is right, it is a characteristic, but it really shouldn't be doing it that often. Try switching gas.

[mrzip]

Hello all just joined and are very interested in all of your knowledge.My C50 was having similar problem when cold . Went to dealer and the changed to higher temp spark plugs seems to have helped a great deal

[wizardone]

BE WARE... Diisconnecting and blocking the two hoses leading from the pair valve to the cylinders will cause an FI failure, maybe not immediately but it WILL happened. I had/have the same problem and after finding that in relation to work that had to be done which required the pipes to be removed 2 or 3 times, the techs did not replace the exhaust gaskets which after being tightened down multiple times, caused them to not seat properly causing air leaks and making the problem worse. They also suggested to bypass the pair valve, in the manner described and sure enough while riding down the highway in heavy traffic, FI failure which almost caused an accident.

If you want to bypass the pair valve, block off the hose ends on the air box and on the input to the pair valve from the air box. For whatever reason, there is enough air flow or vacuum to activate the pair valve and if it is not present it will fail, stalling the engine. You can simply turn the bike off completely and start it again and it will run again until it fails again, but I found this to be a unrecommended situation.

I put aftermarket pipes on with a Dyno Jet Power Commander (fuel management system - recommended by the dealership which I found out later is not necessary on the C90) and a K&N filter in, and all of that enhanced the backfiring problem. As I found out, when the PC was installed, the connections for the power were accomplished with wire tap connections. This eventually cut through the power wires causing intermittent connections, which cause the PC to "reboot" especially at lower RPM's. After having the connections soldered, a vast majority of the coughing and a lot of the backfiring went away.

What really made a difference was replacing the exhaust gaskets (every time you remove the pipes), blocking the pair valve the way I described, and having a Dyno Test performed, creating a custom fuel management map for the way my bike is set up and running.

Probably better than 80% of the roughness, backfiring, sputtering has been eliminated, and the power and mpg has increased by 42%. An amazing turnaround.

Insidentally, I also bought mine new, and had the dealership put on the pipes and the PC, and they loaded a map that was no where in the same ballpark as what was needed, and Dyno Jet did not even have a solution.

Hope this helps, let me know.

[E. Yoang]

Hi, I'm an idiot, I bought a new c90, mine started slight popping and gurgling on decel, after I installed aftermarket parts, I thought it sounded pretty cool, everybody says that it sounds mean also, a few guys even wanted to know how I did it cause they wanted theirs to sound like mine, but after reading this post, the popping and gurgling is not good to have, huh?

[frostbitevinnie]

Popping on decel sounds cool?? Since when?? It would help if you were more specific as to what you have installed. Pipes, FI controller, high flow filter, etc... Usually if just a new pipe install a FI processor is not necessary. The popping could also, I know from experience, be caused by your exhaust crush gaskets either being damaged on install or not properly seated. Did you put new ones in?? They are typically a one time use gasket. Did you torque the header bolts down slowly and evenly to 17ftlbs?? Blah, blah, blah...