R1200RT Exhaust Noise on Deceleration

[St0nkingByte]

My RT, I think, has always burbled a little on deceleration. Its mainly noticeable if I'm running 4-5k RPM in first and then close the throttle. In the past I'm pretty sure I'd hear a little burbling deep in the pipe on deceleration. No big deal I figure it's the PAIR valve doing its emissions control thing by injecting clean air into the exhaust to burn off unused fuel. However lately the burbling has been getting louder and the past couple days I've gotten what almost sound like backfires but they're not quite that loud. More like a loud slap than a burble. So I'm wondering if this is normal on other R1200RTs or if I should consider a trip to the shop.

 

There are two potentially mitigating factors in my observations of the burbling. First off I've been running higher RPMs than I was in the past. Before I had cruiser-guy'itis and was always shifting at or just below 4k. These days I'm not shifting until over 4k somewhere. This is causing me to do alot of my 25-30mph riding in first and thus more 'violent' drop in RPMs if I come off the throttle.

 

Second I'm running a tank of gas from a station I don't normally fill up at. Typically I feed the RT premium from the same Chevron all the time but right now I've got some different gas in there. Obviously if the RT is a touring machine visiting a strange gas station probably shouldn't cause it to go nuts but just an observation.

 

Right now I'm thinking of running through this tank and seeing if the louder more frequent burbling with the loud bang/slaps goes away before I really start to freak out.

[Mudman]

There is no air injection into the exhaust side on your engine. In fact the engine injectors should be turned off on decleration and come back on at 1500 RPM if the throttle is chopped.

 

Two things to consider,

An exhaust leak between the muffler and exhaust port of the heads. This will cause popping and backfires when there is residual un burned fuel remaining in the system.

 

Second guess is your throttle isn't telling the BMS that you have released the throttle. Check your throttle cables for adequate free play at the handlebar and run a throttle pot range procedure with the key on, kill switch in run, and engine not started. You should slowly roll the throttle all the way to full and slowly back to off throttle three times to set the system. Turn off the key and then restart. Hope this helps.

[HexST]

I believe you are hearing it more now because of you different riding style. The catalitic converter can only hide so much of the normal backfires from a big twin engine.

[weshsu]

what almost sound like backfires but they're not quite that loud.

 

I noticed what sounds like the same thing on my brand new R12RT. I've been riding my R1100S for years where I never heard these "backfires", so it certainly surprised me. It only happens on deceleration and it does happen often. I need to analyze this some more to see if it's due to my riding style. So far, I had just assumed this was normal. Is it not?

 

Wes Hsu

'06 R1200RT

'01 R1100S

[Rusty1945]

My RT, I think, has always burbled a little on deceleration. However lately the burbling has been getting louder and the past couple days I've gotten what almost sound like backfires but they're not quite that loud. More like a loud slap than a burble. So I'm wondering if this is normal on other R1200RTs or if I should consider a trip to the shop.

Mine has made similar noises since birth. I noticed its a bit worse during warmup which I suppose is due to a richer mixture. It hasn't really bothered me - the bike is running fine so I consider it to be just a part of the experience.

[crashtap]

I'll throw my hat in, my 2005 R1200RT does the same thing. The more RPM before decelleration, the more I notice the burbing and belching. Kind of reminds me an indy car under the same circumstances, albeit a much different note.

[black99S]

I noticed what sounds like the same thing on my brand new R12RT. I've been riding my R1100S for years where I never heard these "backfires" ... It only happens on deceleration and it does happen often ... So far, I had just assumed this was normal. Is it not?

 

It's normal for the RT to 'pop' as described in this thread.

 

My 99R11S with Z-technik exhaust sometimes gave some real good 'shotgun loud pops' on deceleration if you had closed the throttle from high revs then rolled it open slightly or modulated the throttle near the closed position. This was partly due to an air leak at the up pipe junction, the rest was agressive riding style. All adjustments were perfect otherwise.

The RT has a tight exhaust system with no air leaks so this can't be the source. I have noticed my RT 'popping' a little more after the 1000k service, but at the same time it is idling rougher, so I think correct TPS / cable adjustment will lessen the 'pops' but won't eliminate them.

[St0nkingByte]

Sweet. Thanks for the feedback. The biggest reason I ask is this week I've gotten a couple Harley-esque loud pop noises that seemed no quite right but if you guys say its just part of the boxer character I'll stop worrying and start relishing the racket

[sb955i]

Have you seen my previous thread..

 

R1200RT Backfire Scares Harleys at Americade

 

Mine makes the same burbling... and other notable anomolies