what is that noise

[Jharpphoto]

A couple of weeks ago I accidentally filled the tank of my 2011 RT with "regular" gas.  By midway through the tank I started hearing what I think was combustion clatter sounds while the engine was under load/low RPM's.  I quickly filled the tank with supreme unleaded and the sounds started to dissipate.  Now, my mind/ears might be playing tricks on me but I think I occasionally hear a similar sound only much fainter at around 3-4k rpms while the engine is under load.  The bike has 17.5K miles and It is due for it's 18k service and I know they will address this issue but I want to make sure I'm not doing any additional damage to the engine by riding it.

 

[dirtrider]

13 minutes ago, Jharpphoto said:

A couple of weeks ago I accidentally filled the tank of my 2011 RT with "regular" gas.  By midway through the tank I started hearing what I think was combustion clatter sounds while the engine was under load/low RPM's.  I quickly filled the tank with supreme unleaded and the sounds started to dissipate.  Now, my mind/ears might be playing tricks on me but I think I occasionally hear a similar sound only much fainter at around 3-4k rpms while the engine is under load.  The bike has 17.5K miles and It is due for it's 18k service and I know they will address this issue but I want to make sure I'm not doing any additional damage to the engine by riding it.

 

 

Morning  Jharpphoto

 

You are not the only one to do that, shouldn't have caused any long term problems as your engine has knock sensors (ping sensors) to retard the spark timing when it senses a combustion related knock due to lower octane gasoline.

 

It's not a good policy to run lower octane fuel in your BMW but it won't hurt anything if it happens occasionally.

 

What you are hearing is probably a combination of increased awareness & possibly some valve clatter if you are nearing a service interval.   

[JAllen]

Have been running Regular gas in my 2011 RT for 90000kms. Runs fine. Remember that TV show Long Way Run with Round with Ewan McGregor and Charlie Boorman? Do you think they pulled up to a station in the outback of Kazakstan or the out back of Mongolia and found Premium for their BMW? Hey you dont have to get that crazy. Have you ever done the Alaska Highway. Most of those old stations along the route dont have Premium. In fact when my brother bought his 2010RT the deal breaker was the fact it "needed" premium. Dealer told him not to sweat it, as all would happen is he would not have the 115 hp, say maybe only 100hp.

[dirtrider]

3 hours ago, JAllen said:

Have been running Regular gas in my 2011 RT for 90000kms. Runs fine. Remember that TV show Long Way Run with Round with Ewan McGregor and Charlie Boorman? Do you think they pulled up to a station in the outback of Kazakstan or the out back of Mongolia and found Premium for their BMW? Hey you dont have to get that crazy. Have you ever done the Alaska Highway. Most of those old stations along the route dont have Premium. In fact when my brother bought his 2010RT the deal breaker was the fact it "needed" premium. Dealer told him not to sweat it, as all would happen is he would not have the 115 hp, say maybe only 100hp.

 

 

Morning JAllen   

 

There is a difference between the 1150 bikes that Ewan McGregor and Charlie Boorman were riding & the production 1200 RT.

 

Those BMW 1150 bikes were supplied by BMW so they were probably supplied with the low octane calibration BMW made available for low octane regions.

[JAllen]

Ah point taken on the old bikes. Forgot how long ago that was. None the less I guess we could argue till blue in face, but over on one of the other forums the same subject came up. A chap with a 2007 has never run a tankful of premium in 179000 miles and the bike has not blown up. I guess if you are a rider that has to wring every possible bit of power out your engine in every gear all the time one better stay with  premium. I know my bike runs perfectly fine on regular and in Canada the land of pay pay pay, premium is 90cents a gal more than regular. That like $5 a tank. Means nothing if your bike is a garage Queen

[dirtrider]

36 minutes ago, JAllen said:

Ah point taken on the old bikes. Forgot how long ago that was. None the less I guess we could argue till blue in face, but over on one of the other forums the same subject came up. A chap with a 2007 has never run a tankful of premium in 179000 miles and the bike has not blown up. I guess if you are a rider that has to wring every possible bit of power out your engine in every gear all the time one better stay with  premium. I know my bike runs perfectly fine on regular and in Canada the land of pay pay pay, premium is 90cents a gal more than regular. That like $5 a tank. Means nothing if your bike is a garage Queen

 

Evening JAllen

 

That kind of depends on how a rider rides the bike.   The knock sensors in conjunction with the BMS-K have the ability to retard the spark but there is a limit on how much spark advance  it can remove.

 

Remember it IS a high compression engine without variable cam timing so if pushed hard enough, especially sustained high speed under load (like into a strong headwind at high speeds)  then engine damage can result.

 

Canada is kind of strict on speeding so when I travel there I don't see the sustained  speeds that we see in the US  but in the US in some states we can do a couple of hours at  95mph+  & THAT can do damage if sustained with low octane fuel & a load.

 

In fact BMW published a service bulletin covering extended hard usage causing engine damage if at least 91 AKI fuel was not used.  (I think they even had an updated computer calibration for police bikes due to that)

 

Light duty or moderate riding then I doubt that a rider would ever experience a problem with lower octane fuel.

 

I know a couple of riders that use (mostly) regular gasoline in their 1200 bikes but their idea of speeding is doing 74mph in  posted 70 zone.

[JAllen]

Point taken.

[RTJohn]

I was in Canada recently with my low fuel icon flashing at me. I pulled into a gas station in Awana. All they had was regular. I fueled up and took off. My 2013 RT never noticed the difference. I still fill up with premium but I don't hesitate to use regular if I have to.