R1150RT backfire

[lomaxcm]

I know this is sacrilegious but my 2004 R1150RT came with a Two Brothers cat eliminator exhaust system on it. I am kind of getting used to the sound but on deceleration it back fires something awful. I have looked closely and there are no exhaust leaks.

 

Has anyone ever come up with a solution for this other that doing a power commander?

 

If it continues then the stock system is going back on as I just can't stand it. LOL:

 

Marc

[essman]

I have a Two Brothers that was too loud (2003 R 1150 RTP 103K) and it just didn't sound good, though it seemed to make the bike peppier and. I took out the baffles and welded additional baffles to the original ones-adjusted the Techusion. Sounds better now ( quieter and less raspy) and runs better. I'm running a Ztechnic on a R1200C and that sounds real nice out of the box, a nice low rumble.

[T__]

Marc, is it really backfiring or more like post firing out the exhaust? I’m guessing you are getting dropped throttle post firing in the exhaust or muffler?

 

Usually when you have a popping or post firing in the muffler or exhaust it is from a very lean mixture in the exhaust that ignites when it gets near the end of the muffler or tail pipe.. On your BMW the computer actually turns the fuel off during a lot of closed throttle decels..

 

Popping in the muffler of aftermarket exhaust systems kind of comes with the territory as there are few baffles in the system,, no cat to continue burning the exhaust,, & due to the straight through design allow a negative pressure wave to travel back into the exhaust system & allow combustion way up in the system..

 

You might want to verify your TPS is set correctly & if that is OK then try adding an aftermarket fuel controller to add fuel on decel,, or add some more restriction to the negative wave like more muffler baffles,, or some sort of a wave breaker (like a washer or baffle in the muffler outlet)..

 

I seriously doubt you will completely remove the post firing but with diligent work you can probably lower it to an acceptable level..

 

 

Twisty

 

[lomaxcm]

Twisty,

 

I think you are explaining it better than I with the post firing. On deceleration if I close the throttle ALL of the way it is just fine, but crack the throttle any at all and bing, bam, boom. It also seems to get less noticeable the hotter everything gets, like after a 1/2 hour of riding. I might play with increasing the back pressure somehow and then probably give up and put a stock exhaust back on. After all it is an RT. LOL:

 

Marc

[T__]

Marc, when you close the throttle ALL the way your fueling system shuts the fuel completely off (no fuel = no post firing).. When you don’t close it completely the darn thing won’t shut the fuel off on decel & you get just enough unburnt fuel in the exhaust system to go lean then pop & fart..

 

You really don’t want or need to add back pressure (back pressure is a bad thing) you just need to break up the negative wave traveling back into the muffler.. Even then on a straight through muffler it is difficult to stop post firing without also adding more fuel into the exhaust gas (or alternately shutting the fuel off completely)..

 

 

Twisty

 

[David R]

I just removed the cat from my stock muffler. What a job. I did it and got it right. I get the same post firing as you correctly call it if I don't close the throttle all the way. I can live with it.

 

107,000 miles on the cat and it still looked fine, no signs of it getting plugged.

 

Took 6 hours most of it tig welding the muffler back together. I performed the surgery on the top of the muffler so you can't even see what I did. Used a plasma cutter and 308L stainless filler.

 

It is only a little louder, not enough to notice and a little deeper tone.

 

I also removed the o2 sensor (it was unhooked anyhow)

 

Today I shut off the techlusion. Bike seems to run fine. Idle is the same as before, power is there with no surging. Throttle response is smooth.

 

David

[lomaxcm]

I gave up and put the stock exhaust back on this morning. I think it actually runs better with the huge piece of lead hanging under it LOL: No more after pop and cackle and it sounds more like a BMW motorcycle instead of a 1966 VW with and exhaust leak.

 

I guess I will make a planter box out of the Two Brothers exhaust.

 

Marc