New R1250RS “Pinking” noise

[squibb34]

Whilst I don't get this syndrome with my 1250RS (7k miles) ....yet, I have noticed it happening on other bikes & cars, indeed one car where it would take a second or two for the knock sensors/ECU to adjust to pre-ignition when under load at low speed - an occasional annoyance that never developed into a problem.

Surely it has to relate to the effect lean fuelling with all modern ICEs, as it disappears when engines are de-catted &/or mixtures richened slightly in certain parts of the rev range (Hilltop?). Hopefully the mothership has provided us with piston crowns capable of dealing with occasional pinking.

 

[jetjock]

My R1250RS seems to pink with 95 octane only

 

[the woodster]

Hi, new member, new bike. I took delivery of a new 1250 RS in August having had a 1200 RT and a Nine T in the past. From new, I have a “Pinking” noise when accelerating under load in lower gears at around 3000 revs. I am not “lugging” the bike and it revs very smoothly when not in gear. It has been through its 600 mile service and dealer says all ok. This gets some mention online but it all seems inconclusive with “some of them do that”. Do other owners experience the same ? Is this just a feature of Euro 5 fueling for this engine and bike ? Thanks for taking the time to read.

Hi, I noticed this straight away when my 1250 was new. I call it a 'tinkle'. It's fine and I've come to like it.

 

[Caterham07]

Whilst I don't get this syndrome with my 1250RS (7k miles) ....yet, I have noticed it happening on other bikes & cars, indeed one car where it would take a second or two for the knock sensors/ECU to adjust to pre-ignition when under load at low speed - an occasional annoyance that never developed into a problem.

Surely it has to relate to the effect lean fuelling with all modern ICEs, as it disappears when engines are de-catted &/or mixtures richened slightly in certain parts of the rev range (Hilltop?). Hopefully the mothership has provided us with piston crowns capable of dealing with occasional pinking.

Thank you. The thing that interests me is how modern highly developed engines manufactured to such high engineering and quality standards from a single plant differ in terms of exhibiting this sound out of the crate.

 

[Caterham07]

Hi, I noticed this straight away when my 1250 was new. I call it a 'tinkle'. It's fine and I've come to like it.

I like that … I will embrace the “tinkle”.

 

[Caterham07]

My R1250RS seems to pink with 95 octane only

It seems to be so random. Thank you.

 

[Morety]

From my own experience with boxers, I'm convinced that with increase back pressure under a closed flapper valve right in the lean running area is a contributing factor and bikes will (and mine have) varied with regards to the position of the valve, or more accurately, with whether it was a bit "sticky". Another good reason to either bypass the flapper or to ensure it's regularly serviced (I do mine every 5 months).

 

[Caterham07]

From my own experience with boxers, I'm convinced that with increase back pressure under a closed flapper valve right in the lean running area is a contributing factor and bikes will (and mine have) varied with regards to the position of the valve, or more accurately, with whether it was a bit "sticky". Another good reason to either bypass the flapper or to ensure it's regularly serviced (I do mine every 5 months).

That makes a lot of sense. If you assume the EUC’s are identical as are injectors / plugs, the two mechanical elements are cams /valves and the “flap”. You would hope a new bike would have tight tolerances on cams and be timed to spec. The one area that may have a little wiggle room would be the valve. This may account for the variation in experiencing te “tinkle”. I would not delete it but I have read on the forums it is worth keeping an eye on.

 

[Hann]

My bike has a Healtech and the silencer can has been completely de-baffled resulting in - if it even is a thing - minimal `backpressure`.
It still has the pinking noise on occasion - my bike is (and was before the previously mentioned mods were performed) only mildly affected and only does it for less than a second or so when initially opening the throttle to accelerate when under moderate load generally in the lower gears. Classic pinking symptoms.

Once it`s done it (the noise) i have noticed that on subsequent throttle openings - for example the next gear changes in similar conditions to when i first noticed the sound - the engine cannot be provoked to make the noise reoccur. This to me suggests that the ECU has detected from the knock sensors that the engine conditions have been unsuitable/is knocking and has adapted the mapping to prevent that knocking from occuring again.

 

[Caterham07]

My bike has a Healtech and the silencer can has been completely de-baffled resulting in - if it even is a thing - minimal `backpressure`.
It still has the pinking noise on occasion - my bike is (and was before the previously mentioned mods were performed) only mildly affected and only does it for less than a second or so when initially opening the throttle to accelerate when under moderate load generally in the lower gears. Classic pinking symptoms.

Once it`s done it (the noise) i have noticed that on subsequent throttle openings - for example the next gear changes in similar conditions to when i first noticed the sound - the engine cannot be provoked to make the noise reoccur. This to me suggests that the ECU has detected from the knock sensors that the engine conditions have been unsuitable/is knocking and has adapted the mapping to prevent that knocking from occuring again.

That’s something I will test when the riding season returns. It’s an interesting subject that you would think BMW would have a formal position on that would reassure owners. As I read the the forums, a few owners have changed out of 1250’s because of the uncertainty and the lack of explanation from BMW. For many the sound comes with the onset of higher mileage and others like me have it from new. Some are making all sorts of changes to cam timings and exhaust flaps. This tends to be on higher mileage bikes. I am going to ride around or through it like any other engine characteristic and enjoy the bike. Many thanks for responding.

 

[casbar]

From my own experience with boxers, I'm convinced that with increase back pressure under a closed flapper valve right in the lean running area is a contributing factor and bikes will (and mine have) varied with regards to the position of the valve, or more accurately, with whether it was a bit "sticky". Another good reason to either bypass the flapper or to ensure it's regularly serviced (I do mine every 5 months).

Nope, mate has a 1250RT with the flap disconnected and open, and the eliminator thingy, still get the sound. On my own bike it has got better with more miles and goes away if you don't lug the engine and rev it.

 

[Mr Bean]

Nope, mate has a 1250RT with the flap disconnected and open, and the eliminator thingy, still get the sound. On my own bike it has got better with more miles and goes away if you don't lug the engine and rev it.

Fairly sure they fail in the open position.

 

[casbar]

Fairly sure they fail in the open position.

Yes they do, so if you disconnect it or it is failed it is normally fully open. Morety theory was the sound happens when the flap is closed. On my bike you can get the sound in any throttle posn, so the flap would be open if you are accelerating.

 

[Mr Bean]

Yes they do, so if you disconnect it or it is failed it is normally fully open. Morety theory was the sound happens when the flap is closed. On my bike you can get the sound in any throttle posn, so the flap would be open if you are accelerating.

Same as mine.

 

[Caterham07]

Nope, mate has a 1250RT with the flap disconnected and open, and the eliminator thingy, still get the sound. On my own bike it has got better with more miles and goes away if you don't lug the engine and rev it.

Helpful to know this may change over time. Thx.

 

[Caterham07]

Yes they do, so if you disconnect it or it is failed it is normally fully open. Morety theory was the sound happens when the flap is closed. On my bike you can get the sound in any throttle posn, so the flap would be open if you are accelerating.

Thanks for feedback.

 

[GelandeStress]

Thx Morety,

From all I am learning from the site I should ride and enjoy as there is no evidence of any issues with the bike and it is a delight to ride. I have a little collection of classic bikes from 50's, 60's and 70's and spend probably too much time tuning carbs, hence I have leapt to the "pinking" from lean fuelling as an explanation. I have Suzuki GT750 2 stroke triple where exhaust back pressure / expansion chambers can made a difference to performance by regulating the gas flow within and leaving the cylinder through the port. The complexity of Euro 5, the ECU and how they it responds to a knock sensor is beyond me ... better Brains than mine will have worked it all out. Thank you for taking the time to reply.

Hi, sorry for the late post. I just had my R1250GS engine replaced due to this noise. I took it to BMW and said if you can't diagnose it then it's not safe to ride, I won't accept 'we don't know what it is'. I suggest you push on this! Also, put a camera/gopro on your bike to record the noise, it's MUCH easier to get it sorted if you can provide evidence.

Here is the sound my bike made, is this similar to yours? Low RPM acceleration in any gear and 70mph on the motorway.
Rattle sound video 1
Rattle sound video 2

 

[Morety]

Yep, had that on both my 1200's from low RPM under load. Typical pinking sound. The GSA was the worst as the pinking carried on well into the mid revs region. Don't appear to have it on the 1250 now, except for a very brief rattle under load which goes away within a second or two, after the knock sensors pick it up and alter the fuelling/ignition timing (not sure if it's one or both). Not concerned about a brief moment of pinking, but was concerned on previous 1200's as it was loud and not as rev dependant in that it could occur from mid revs as well as low revs. Warm engine under low revs in lower gears was when it seemed worse.

 

[Caterham07]

Hi, sorry for the late post. I just had my R1250GS engine replaced due to this noise. I took it to BMW and said if you can't diagnose it then it's not safe to ride, I won't accept 'we don't know what it is'. I suggest you push on this! Also, put a camera/gopro on your bike to record the noise, it's MUCH easier to get it sorted if you can provide evidence.

Here is the sound my bike made, is this similar to yours? Low RPM acceleration in any gear and 70mph on the motorway.
Rattle sound video 1
Rattle sound video 2

Many thanks for the videos and your experience. The noise on the recordings is louder and rougher than the "pinking" I have at low revs. I can see why you pressed for your engine to be replaced if they could not diagnose the cause of such a mechanical sound from the engine and drive train. I hope the bike is running well now.

 

[Caterham07]

Yep, had that on both my 1200's from low RPM under load. Typical pinking sound. The GSA was the worst as the pinking carried on well into the mid revs region. Don't appear to have it on the 1250 now, except for a very brief rattle under load which goes away within a second or two, after the knock sensors pick it up and alter the fuelling/ignition timing (not sure if it's one or both). Not concerned about a brief moment of pinking, but was concerned on previous 1200's as it was loud and not as rev dependant in that it could occur from mid revs as well as low revs. Warm engine under low revs in lower gears was when it seemed worse.

Thanks for the feedback, your experience seems to mirror mine.