Which Octane is preferred?

[yechave]

When we bought our R1100RT, I was told to only use 91 or better octane. I read another post someone was using 89. Is there one correct answer here? No sense spending extra money if the higher octane is not necessary.

 

Thanks!

[OoPEZoO]

Try running the lower octane and see how your bike reacts. If you notice pinging on hard or loaded acceleration, move back to the high test. Personaly, it depends on where I fill up. If I fill up in PA (near home), I use midgrade. If I fill up in MD (near work), I use premium. The MD gas is pure crap and I try to avoid it, but sometimes I get stuck with it when I'm not paying attention to the odometer. I don't know what they put in their gas, but I know my bike doesn't like it.

 

PA midgrade gets me 41-44 mpg

MD premium gets me 37-40 mpg

I don't notice a difference between the PA midgrade and premium so I tend to stick with the midgrade, but anything less than premium in MD makes my bike run awefull.

 

I would say just experiment and see what your bike likes. I'm pretty sure you could easily get away with midgrade. When I'm out of town, I always go with the premium. Just my $.02

[NonComp]

If your ears are better than mine, try filling up with the lower octane and then drive while keeping an ear open for pinging. If you hear pinging, then you need to boost the octane to prevent detination. If you want a controlled experiment, you can purchase octane boost additive at an auto supply store before you try this. Fill with regular, drive, add some octane boost if hear pinging (to prevent engine damage).

[russell_bynum]

Run the lowest octane that you can get away with.

 

My R1100RT did fine with the cheap stuff except in the hottest summer months...then I'd switch to mid-grade.

[swfraley]

I figure the book says 91 for a reason.

 

As I understand it, "pinging" and detonation are not the same thing. Pinging (a/k/a knocking) is pre-ignition, and you can hear it. You can't hear detonation, which happens when a too-lean fuel-air mixture explodes instead of burning. So, you can have detonation threatening to tear up your engine and not know it. Burning a fuel with lower than recommended octane predisposes to detonation.

 

I heard all of this from a flight instructor, talking about airplane engines. It may not be true for oilhead boxers. For that matter, it may not even be true for airplane engines. Flight instructors have been known to talk out of their hats, especially about engines. It makes sense to me, though.

 

And again, I can't imagine why the manual would say 91 if you could safely and reliably use 87 or 89.

[Tony_K]

And again, I can't imagine why the manual would say 91 if you could safely and reliably use 87 or 89.

 

BMW also said that the 1200rt series had lifetime oil in the FD.

 

Now who you going to trust or believe?

[Antimatter]

I've been running 87 octane in my 2000 RT for the last 10,000 miles with no apparent ill effects.

[smiller]

I've been running 87 octane in my 2000 RT for the last 10,000 miles with no apparent ill effects.

I've been running 87 octane in my 1996 RT for the last 90,000 miles with no apparent ill effects.

[WaywardSon]

Ran premium for several months after getting my 96 R1100RT & then switched to mid-grade after reading a similar thread (here I think). I have since started using 87 octane & have run that for a few thousand miles. Haven't heard a ping yet & the bike runs great.

[Tipover_Bob]

When we bought our R1100RT, I was told to only use 91 or better octane. I read another post someone was using 89. Is there one correct answer here? No sense spending extra money if the higher octane is not necessary.

 

Wayne:

I believe these bikes are air/oil cooled, insinuating their operating temperatures may vary a bit. On a hot day, idling in traffic, would be a good day to have 91 octane fuel in the bike. If you can pick and choose when these conditions arise, you might be just fine running a regular grade fuel. Like it or not, BMW is probably being cautious on their octane recommendations.

Tipover Bob

[T__]

I figure the book says 91 for a reason.

 

As I understand it, "pinging" and detonation are not the same thing. Pinging (a/k/a knocking) is pre-ignition, and you can hear it. You can't hear detonation, which happens when a too-lean fuel-air mixture explodes instead of burning. So, you can have detonation threatening to tear up your engine and not know it. Burning a fuel with lower than recommended octane predisposes to detonation.

 

I heard all of this from a flight instructor, talking about airplane engines. It may not be true for oilhead boxers. For that matter, it may not even be true for airplane engines. Flight instructors have been known to talk out of their hats, especially about engines. It makes sense to me, though.

 

And again, I can't imagine why the manual would say 91 if you could safely and reliably use 87 or 89.

 

 

And again, I can't imagine why the manual would say 91 if you could safely and reliably use 87 or 89.

 

Stuart, mostly because the manual doesn’t know where you ride,, what altitude you ride at,, how hot it is where you ride,, the time of year it is when your ride,, the load you carry when you ride..

 

I seriously doubt you would want to pull Baker Grade on a hot dry mid summer day with a passenger & luggage on 87 octane fuel..

 

On the other hand I doubt you would need 91 octane on a cool moist 1000 foot above sea level one up morning ride.. Altitude figures in here,, as you go up in altitude the octane requirement goes down..

 

The problem is if you go too low on the octane you can damage your engine.. While you can usually easily hear low speed poor fuel related pinging (that doesn’t damage much anyway).. I seriously doubt anybody could hear high speed detonation & that is an engine killer..

 

If you install a fuel controller or other way to richen the fuel mixture you probably could use a lower octane fuel.. Most production 1100 or 1150 boxers operate in the 14.7 stokeometric window while cruising down the hiway & that is plenty lean to use low octane fuel under high loads in hot weather..

 

Just watch your spark plugs if you choose to run lower octane fuel.. Those will show the first signs of impending engine damage.. Eroded electrodes & signs of aluminum on the plug porcelains are danger signs..

 

If you run a lot of very high speed freeways probably using a low octane fuel isn’t a good idea unless you can figure out a way to hear your engine over the high ambient wind & traffic noise..

 

Twisty

[philbytx]

I run Premium in mine...as per the book. Then again, I am entirely anal and just HATE to second guess myself

[dave_jo]

93 octane...about $1 more than 87 octane per tankfull. About half a cent per mile.

 

I just figure that's one thing I don't have to worry about.

[realshelby]

Pinging or Detonation are simply terms that cover the noise heard in an engine that is suffering from uncontrolled fuel burn. "Pre-ignition" is simply a fuel/air mix that was ignited by something in the combustion chamber other than the intended source (spark plug). Usually a piece of carbon build up that stays hot enough to ignite the mixture but can be spark plugs overheated or sharp metal edges in the combustion chamber. "Pinging" under light throttle load may not be harmful, some auto companies suggest this to be allowable in the owners manual.

"Detonation" is the uncontrolled burn of fuel/air after it has been ignited by the spark plug or injection circuit. It is literally an explosion instead of a smooth linear expansion of the flame kernel. You CAN hear detonation. More apt to hear this under heavy load/throttle position. Left unchecked it can cause catastrophic engine failure. Combustion pressures in the combustion chamber can be several times the standard pressure during a detonation burn.

[NonComp]

Pinging or Detonation are simply terms that cover the noise heard in an engine that is suffering from uncontrolled fuel burn. "Pre-ignition" is simply a fuel/air mix that was ignited by something in the combustion chamber other than the intended source (spark plug). Usually a piece of carbon build up that stays hot enough to ignite the mixture but can be spark plugs overheated or sharp metal edges in the combustion chamber. "Pinging" under light throttle load may not be harmful, some auto companies suggest this to be allowable in the owners manual.

"Detonation" is the uncontrolled burn of fuel/air after it has been ignited by the spark plug or injection circuit. It is literally an explosion instead of a smooth linear expansion of the flame kernel. You CAN hear detonation. More apt to hear this under heavy load/throttle position. Left unchecked it can cause catastrophic engine failure. Combustion pressures in the combustion chamber can be several times the standard pressure during a detonation burn.

Excellent explanation.

[NonComp]

P.S. Carbon build up, in addition to causing pre-ignition, could also cause run-on in older carburated engines (runs for a short time after the ignition is turned off).

[AndyS]

Pinging or Detonation are simply terms that cover the noise heard in an engine that is suffering from uncontrolled fuel burn. "Pre-ignition" is simply a fuel/air mix that was ignited by something in the combustion chamber other than the intended source (spark plug). Usually a piece of carbon build up that stays hot enough to ignite the mixture but can be spark plugs overheated or sharp metal edges in the combustion chamber. "Pinging" under light throttle load may not be harmful, some auto companies suggest this to be allowable in the owners manual.

"Detonation" is the uncontrolled burn of fuel/air after it has been ignited by the spark plug or injection circuit. It is literally an explosion instead of a smooth linear expansion of the flame kernel. You CAN hear detonation. More apt to hear this under heavy load/throttle position. Left unchecked it can cause catastrophic engine failure. Combustion pressures in the combustion chamber can be several times the standard pressure during a detonation burn.

Where do you get your info from??

Surely the whole idea of a good combustion is to burn the fuel as quickly as possible at the instant the spark plug is energised. The result is fundamentally an explosion - which is what we use to push the pistons down.

Surely pinking or detonation are the same thing - In so much as the fuel is being burnt at the wrong time. This could be pre-ignition brought on by a timing problem, or by a carbon build up in the combustion area or air leaks etc.

Andy

[NonComp]

Where do you get your info from??

Surely the whole idea of a good combustion is to burn the fuel as quickly as possible at the instant the spark plug is energised. The result is fundamentally an explosion - which is what we use to push the pistons down.

I would say that this statement is dead wrong. Engines are carefully designed for a controlled burn. There is a lot of science behind how this is controlled and why it is necessary. My information comes from autoshop 101 circa 1972 or so.

[GregB]

"Pinging" is simply a common name for Preignition or Detonation that you can hear. It describes the sound, not the source of the noise.

Normal ignition is a controlled flame front expanding across a combusion chamber that is expanding (piston travelling down) in controlled manner to create maximum BMEP and therefore eficiency. The person that explains normal ignition and pinging as explosions is incorrect. An explosion causes all kinds of problems such as destroying the boundry layer of cooler gases that exists in a combustion chamber that helps keep the heat of combustion creating power instead of going into the cooling system.

There are a variety of causes of pinging such as:

- Ignition of the normal spark too early so that the flame front is expanding into a combustion chamber that is contracting or not expanding at the proper rate.

- Too-low octane gas so that the heat of compression fires the mixture in the same way that a diesel engine works normally.

- hot spots in a combustion chamber that fire the mixture.

 

Any extra firing (by something other than the sparkplug) can cause two flame fronts to hit each other causing pinging.

 

To answer the original question: Any gasoline that works without pinging is good enough. Nothing is gained by using higher octane gas if the lower does not ping. The specification of the manufacturer is simply what is required for normal use. Other factores change that such as temperature, altitude, carbon build up, etc.

[T__]

snip~ Surely the whole idea of a good combustion is to burn the fuel as quickly as possible at the instant the spark plug is energised. The result is fundamentally an explosion - which is what we use to push the pistons down.

Surely pinking or detonation are the same thing - In so much as the fuel is being burnt at the wrong time. This could be pre-ignition brought on by a timing problem, or by a carbon build up in the combustion area or air leaks etc.

Andy

 

 

 

Andy, pinging & detonation are NOT the same thing.. Pinging is usually PRE-IGNITION.. That is the fuel air mixture igniting BEFORE the spark occurs either due to low octane fuel igniting on the compression heat, or something glowing hot in the combustion chamber igniting it before the actual spark takes place..

 

Detonation is the fuel air mixture igniting with the spark at the CORRECT TIME but instead of burning in a controlled fashion it EXPLODES uncontrollably therefore pressurizing the remaining fuel air mixture so it ignites on the heat/pressure of the explosion rather than a controlled burn.. Detonation produces one heck of a shock wave & is very detrimental to engine parts..

 

Twisty

[smiller]

I've heard all manner of pinging from more engines than I can count but I'm wondering if I've ever heard true detonation. Is the sound of the latter different in any way?

[philbytx]

I reckon you HAVE heard it!

 

Bet you been behind a Harley with straight pipes at least once in your life :

[onoboy1]

Eh Brah, no be cheap after you went drop 20 grand on one beema. Just bite da bullet and spring for da highest da kine octane heh. My manual says 98 octane for optimal performance. So I even trow some Primo beer in da tank because I like to fly all da time. Aloha!

[wilee]

93 octane...about $1 more than 87 octane per tankfull. About half a cent per mile.

 

I just figure that's one thing I don't have to worry about.

 

Truer words could not be spoken.

[ShovelStrokeEd]

Jeepers, 3 pages and not a single mention of how the octane is calculated. There are two different methods in conventional use plus an amalgam of the two commonly used here in the US of A.

 

R method produces a high number such as the 97 or 98 octane mentioned used in EU countries.

N method, I forget what it stands for, produces a low number, as low as 83 for regular gas. I don't know where this is in common use outside of fuel company laboratories.

(R+N)/2 method, in common use here, is the mean between the two. So, mfg recommends 91 octane. By which method. A 91 octane fuel measured by the research method is likely to mean 89 here in the states.

[Boffin]

Jeepers, 3 pages and not a single mention of how the octane is calculated. There are two different methods in conventional use plus an amalgam of the two commonly used here in the US of A.

 

R method produces a high number such as the 97 or 98 octane mentioned used in EU countries.

N method, I forget what it stands for, produces a low number, as low as 83 for regular gas. I don't know where this is in common use outside of fuel company laboratories.

(R+N)/2 method, in common use here, is the mean between the two. So, mfg recommends 91 octane. By which method. A 91 octane fuel measured by the research method is likely to mean 89 here in the states.

 

Ed, That is RON for Research Octane Number and MON for Motor Octane Number. At normal road fuel values they are approximately 10 units apart so 95 RON is 85 MON or 90 AKI.

 

AKI stands for Anti Knock Index and is, as you say, RON+MON/2.

 

Andy.

[Little Joe]

1 gallon of 89 octane mid-grade: $3.05

1 gallon of 91 octane premium: $3.17

Cost difference of a 5 gallon, $15.00 fill-up: $0.60

Cost of a new RT: about $18,000

Peace of mind that comes from knowing I'm not doing anything to unnecessarily jeopardize my bike's reliability: priceless.

[Dick_at_Lake_Tahoe_NV]

93 octane...about $1 more than 87 octane per tankfull. About half a cent per mile.

 

I just figure that's one thing I don't have to worry about.

 

Here's another perspective: I just paid $260 for a pair of Conti Toad attacks mounted on my bike. I got 7,000 miles out of them and that's almost 4-cents/mile for tires. I'll easily go the 1/2-cent per mile for 91 over 87 octane.

 

Truer words could not be spoken.

[Little Joe]

I just paid $260 for a pair of Conti Toad Attacks mounted on my bike.

If you lick the Toad Attacks, will you hallucinate?

[Bob Palin]

1 gallon of 89 octane mid-grade: $3.05

1 gallon of 91 octane premium: $3.17

Cost difference of a 5 gallon, $15.00 fill-up: $0.60

Cost of a new RT: about $18,000

Peace of mind that comes from knowing I'm not doing anything to unnecessarily jeopardize my bike's reliability: priceless.

126,000 miles at 40mpg = 3150 gallons at 12c/gal = $378, not as bad as I thought, glad I've been using 91

[smiller]

126,000 miles at 40mpg = 3150 gallons at 12c/gal = $378, not as bad as I thought, glad I've been using 91

Unless of course using 91 octane has been unnecessary, in which case you spent $378 for nothing.

[RFW]

When we bought our R1100RT, I was told to only use 91 or better octane. I read another post someone was using 89. Is there one correct answer here? No sense spending extra money if the higher octane is not necessary.

Your last sentence is absolutely right.

 

But never mind what octane rating you were "told" to use. Opinions are simply opinions. Best is to simply use the octane rating that BMW has stated to use in the manual. If you have no manual, then the dealer can tell you what BMW's requirement is.

[Bob Palin]

126,000 miles at 40mpg = 3150 gallons at 12c/gal = $378, not as bad as I thought, glad I've been using 91

Unless of course using 91 octane has been unnecessary, in which case you spent $378 for nothing.

True, I tried a couple of tanks of 89 during my trip to the Un and got instant pinging, it was hot there of course. Up here in the cold I should be able to use a lower octane but we usually get 85, 87 and 90 anyway.

[smiller]

I tried a couple of tanks of 89 during my trip to the Un and got instant pinging,

Well in that case I would say that you are correct in going with the 91.

 

In my case I can't get my bike to ping on 87 octane if I try. I can remember it occurring only once in 90k miles, at 100+ temperatures with the RID at seven bars. But there is apparently a lot of variation between bikes so an owner's personal experience should be the guide.

[Bob Palin]

I am a bit disappointed with the pinging, it's always done it since new though. I'm a regular practitioner of the Italian Tuneup and run a couple of tanks worth of Techron through before each oil change so I shouldn't have carbon buildup.

[ShovelStrokeEd]

Bob,

Doesn't have to be carbon buildup. It is quite possible that your ignition advance, while in specification, is on the high side of said spec. It may even be out of specification. Resetting the ignition timing down a couple of degrees might allow you to switch to 87 and save that $378 over the next 125K miles.

[Capt_Ron]

I began noticing some pinging in my engine during our last road trip to NC. Assumed it was bad gas. Doesn't happen unless I'm in a tall gear headed up a slope. Pouring on the fuel then really makes it clatter. The condition has persisted after our return. If I'm headed up a fairly steep hill, the bike seems to have the power to hold speed but I don't want to hear the clatter, so I throttle back a bit and down shift if I have to before reaching the top.

 

Got my 24K and annual service done at the BMW shop yesterday and the bike is running fine, but at highway speed, if I roll on the throttle for a hard acceleration, I still get that knocking sound (sounds like a machine gun). I always fuel up with the highest octane gasoline available, usually 91-93.

 

Please tell me its just the gas. Maybe I should try some octane booster. I've had the bike about 6 months and I didn't notice this pinging until last month.

 

Ron

 

 

 

I thought maybe the timing is out of adjustment slightly

[ShovelStrokeEd]

Not enough information to determine the cause of pinging on your bike. What speeds? What RPM? What is the history of your driving the bike? Are you a shift at 3000 RPM guy or do you run it up through the gears? When was the last time you rode, non-stop, for a couple of tanks full of gas at highway speeds?

 

I would guess that you are suffering from a little carbon buildup in the combustion chambers. Techron, a Chevron product, can help with this but don't expect any miracles. Dirty injectors can lead to pinging as well. Sea Foam fuel injector cleaner can help with this. Ignition timing can certainly cause it but, if you are already running 91 octane fuel and still experience the ping, my bets would be with riding habits. When I rode my oilhead bike, I never was under 4K RPM if I wasn't just accelerating away from a stop. Rarely in 5th gear below 70 mph or so. Never had any pinging and my fuel consumption was within the average for everybody else who ran at sea level.

[Tipover_Bob]

When I rode my oilhead bike, I never was under 4K RPM

 

Yo, this makes no sense. Put your bike on its center stand. Rev it up to 2500 rpms and listen to it. Then rev it up to 4500 rpms and listen to it some more. Loud isn't it. Lots more throttle needed isn't there. Now since your bike is in neutral, you are not going anywhere, just sitting there. Now think how much more gas you are burning at the higher rpms. Think also at how many more rpms you are turning at the higher rpms for the same distance. So, the guy running say 5000 rpms going 50 mph will twist his engine twice as many times as the guy turning 2500 rpms at 50 mph. Ok, that is the equivilent of driving 100,000 miles while the lower rpm guy only goes 50,000 miles. So, whose bike will last longer? I expect I know. Which bike will be more reliable? I expect I know. Is this rocket science? I don't think so.

Tipover Bob

[ShovelStrokeEd]

Not rocket science, Bob, pseudo science.

 

Let me ask you a question or 2. How much HP does it take to run the bike down the road at say, 60 mph? What proportion of that HP is engine friction?

 

Oh yeah, a third one, why do you think the engine will be more efficient at small throttle openings rather than larger?

[elkroeger]

The program I'm on is to use the lowest octane I can so that it doesn't knock. If it knocks regularly, then move to the next grade higher. If it knocks a lot on premium grade, then consider the possibility something's wrong, like it's time for a tune-up (but I could be wrong).

[Capt_Ron]

Not enough information to determine the cause of pinging on your bike. What speeds? What RPM? What is the history of your driving the bike? Are you a shift at 3000 RPM guy or do you run it up through the gears? When was the last time you rode, non-stop, for a couple of tanks full of gas at highway speeds?

 

I would guess that you are suffering from a little carbon buildup in the combustion chambers. Techron, a Chevron product, can help with this but don't expect any miracles. Dirty injectors can lead to pinging as well. Sea Foam fuel injector cleaner can help with this. Ignition timing can certainly cause it but, if you are already running 91 octane fuel and still experience the ping, my bets would be with riding habits. When I rode my oilhead bike, I never was under 4K RPM if I wasn't just accelerating away from a stop. Rarely in 5th gear below 70 mph or so. Never had any pinging and my fuel consumption was within the average for everybody else who ran at sea level.

Maybe I can provide a little more information.

 

I'm not normally heavy on the throttle, but I do like a little acceleration once in a while. However, the bike is nor a rocket. Try as I may, I often can't beat a Ford pickup off the light. Usually, I accelerate expeditiously through the gears, shifting anywhere at 3000 to 4000 rpms. I cruise along in a gear selected to keep me at around 3800 to 4000 rpms.

 

I only notice the pinging (knocking) sound in 5th or 6th gear when the rpms are between 3000 and 4000 AND I'm accelerating hard or pulling a pretty good grade.

 

The last time I rode "non-stop" was last weekend, Austin to New Branfels to Houston to Brownwood. As a matter of fact, I first noticed this condition in NC on our September 9 states in 9 days trip.

 

I do all of the speed limit wherever I go (hate to waste any of it). I've tried getting gas from different suppliers, Chevron, Texaco, Shell, etc. Sometimes I think there's an improvement, but then I find the condition is not entirely gone. I can induce the effect if I choose to by pulling hard on the throttle while heading up a hill in 6th gear from 70 mph. That would be about 3800 rpm or so.

 

Ed, tell me what I'm doing wrong here. Am I supposed to drive this thing like a sportbike?

Ron

[russell_bynum]

Try as I may, I often can't beat a Ford pickup off the light. Usually, I accelerate expeditiously through the gears, shifting anywhere at 3000 to 4000 rpms.

 

 

Ride it like you stole it.

 

When you're trying to accelerate hard, do it with the throttle pinned, and don't shift until redline.

 

If you bounce off the rev limiter now and then, all the better.

 

Oilheads respond best when you're wringing their necks.

[Tipover_Bob]

Let me ask you a question or 2. How much HP does it take to run the bike down the road at say, 60 mph? What proportion of that HP is engine friction?

 

Oh yeah, a third one, why do you think the engine will be more efficient at small throttle openings rather than larger?

 

Mr. Ed:

Oh dear, oh dear. The answer to number one is lots and lots more because by just turning over an engine uses lots of energy due to internal friction and oil pumping and generator generating and air compressing etc. ad nauseum and the answer to number two is.... I dunno.

 

Might the answer to 2 be the very flat torque curve indicating an engine that is equally efficient at high and low rpms?

Tipover Bob

[Paul Mihalka]

When I rode my oilhead bike, I never was under 4K RPM

 

Yo, this makes no sense. Put your bike on its center stand. Rev it up to 2500 rpms and listen to it. Then rev it up to 4500 rpms and listen to it some more. Loud isn't it. Lots more throttle needed isn't there. Now since your bike is in neutral, you are not going anywhere, just sitting there. Now think how much more gas you are burning at the higher rpms. Think also at how many more rpms you are turning at the higher rpms for the same distance. So, the guy running say 5000 rpms going 50 mph will twist his engine twice as many times as the guy turning 2500 rpms at 50 mph. Ok, that is the equivilent of driving 100,000 miles while the lower rpm guy only goes 50,000 miles. So, whose bike will last longer? I expect I know. Which bike will be more reliable? I expect I know. Is this rocket science? I don't think so.

Tipover Bob

'99 R1100RT bought new, sold in 2005 with over 170K miles in perfect running condition, still running strong with around 200K miles. As much as possible never under 4000rpm. Many two-lane passes at close to rev. limiter. Couple of Reg Pridmore CLASS track events red lining all day. Never had any repair done to the engine. Never had the cylinders/heads off the engine. I rest my case.

[Tipover_Bob]

'99 R1100RT bought new, sold in 2005 with over 170K miles in perfect running condition, still running strong with around 200K miles. As much as possible never under 4000rpm. Many two-lane passes at close to rev. limiter. Couple of Reg Pridmore CLASS track events red lining all day. Never had any repair done to the engine. Never had the cylinders/heads off the engine. I rest my case.

 

Paul:

Absolute proof positive that BMW makes fine products.

Tipover Bob

[ShovelStrokeEd]

I only notice the pinging (knocking) sound in 5th or 6th gear when the rpms are between 3000 and 4000 AND I'm accelerating hard or pulling a pretty good grade.

 

I do all of the speed limit wherever I go (hate to waste any of it). I've tried getting gas from different suppliers, Chevron, Texaco, Shell, etc. Sometimes I think there's an improvement, but then I find the condition is not entirely gone. I can induce the effect if I choose to by pulling hard on the throttle while heading up a hill in 6th gear from 70 mph. That would be about 3800 rpm or so.

 

OK, there are your problems and the bike is probably fine, albeit with a little carbon buildup. Wide throttle openings (accelerating hard) and relatively low RPM, coupled with a high compression engine are going to lead to pinging and possibly even knocking. If you are below 4000 RPM and find yourself in need of quick acceleration, downshift. Don't be afraid, the motor won't come apart. Ditto pulling a long grade.

 

The BMW boxer motor is a wonderfully flexible engine. It does produce a nice, broad spread of torque which makes it easy to fall into the trap of thinking it is tractor kinda motor. Fact is, though, it is a pretty high RPM motor with a high, for a twin, red line. Drop down a gear or even two if the situation calls for it and your pinging will be gone.

[Bob Palin]

When I rode my oilhead bike, I never was under 4K RPM

Yo, this makes no sense.

It makes perfect sense, he is using the motor in the way it was designed to be used, it will operate better and last longer when used in that way. The boxer motor is not intended to be 'lugged', the exact definition of lugging is somewhat disputed but IMHO never cruise under 3500, never accelerate under 4000. I've been doing that for most of 126,000 miles on my '02 1150RT and have had no engine related problems at all. Indeed, during the time before I followed this practice the bike surged and pinged quite badly despite many attempts to tune it by various 'experts'. Run it hard, use the red line/rev limiter regularly and your bike will be happy.

[T__]

Not enough information to determine the cause of pinging on your bike. What speeds? What RPM? What is the history of your driving the bike? Are you a shift at 3000 RPM guy or do you run it up through the gears? When was the last time you rode, non-stop, for a couple of tanks full of gas at highway speeds?

 

I would guess that you are suffering from a little carbon buildup in the combustion chambers. Techron, a Chevron product, can help with this but don't expect any miracles. Dirty injectors can lead to pinging as well. Sea Foam fuel injector cleaner can help with this. Ignition timing can certainly cause it but, if you are already running 91 octane fuel and still experience the ping, my bets would be with riding habits. When I rode my oilhead bike, I never was under 4K RPM if I wasn't just accelerating away from a stop. Rarely in 5th gear below 70 mph or so. Never had any pinging and my fuel consumption was within the average for everybody else who ran at sea level.

Maybe I can provide a little more information.

 

I'm not normally heavy on the throttle, but I do like a little acceleration once in a while. However, the bike is nor a rocket. Try as I may, I often can't beat a Ford pickup off the light. Usually, I accelerate expeditiously through the gears, shifting anywhere at 3000 to 4000 rpms. I cruise along in a gear selected to keep me at around 3800 to 4000 rpms.

 

I only notice the pinging (knocking) sound in 5th or 6th gear when the rpms are between 3000 and 4000 AND I'm accelerating hard or pulling a pretty good grade.

 

The last time I rode "non-stop" was last weekend, Austin to New Branfels to Houston to Brownwood. As a matter of fact, I first noticed this condition in NC on our September 9 states in 9 days trip.

 

I do all of the speed limit wherever I go (hate to waste any of it). I've tried getting gas from different suppliers, Chevron, Texaco, Shell, etc. Sometimes I think there's an improvement, but then I find the condition is not entirely gone. I can induce the effect if I choose to by pulling hard on the throttle while heading up a hill in 6th gear from 70 mph. That would be about 3800 rpm or so.

 

Ed, tell me what I'm doing wrong here. Am I supposed to drive this thing like a sportbike?

Ron

 

Ron, what you are doing is OK as far as BMW is concerned as it is in the owners manual under Flexibility.. They give you both 5th & 6th gear roll on times-to-speed from a fairly low vehicle speed.. If BMW wanted you to keep your RPM’s above 4000 they would tell you that in the owners manual..

 

You shouldn’t be getting a continuous ping as you climb a hill in the higher gears. Maybe a cackle or two as you throttle up but not a continuous pinging..

 

I don’t know which one of your bikes you are complaining about but if the 2004 RT then the first thing I would look for is a fouled lower spark plug.. It will run on the uppers only but not very good..

 

It’s also possible you do a have a carbon build up that has raised the compression slightly,, or something amiss on your base ign timing,, or a lazy fuel injector,, or something else wrong with the engine.. Probably wouldn’t hurt to do a hot engine compression test & if that comes out higher than specifications, suspect a carbon problem..

 

Season of the year can also have a bearing on your pinging.. Especially if the fuel came from the northern climates.. Late fall through late spring will usually get you very high vapor pressure gasoline designed for cold starting enhancement that is prone to spark knock in warm weather or under a hot engine load..

 

Basically a little cackle once in a while on throttle up or a burst cackle as you throttle up under load or climbing a hill won’t hurt anything but a continuous ping that stays for more than a few seconds is bad news for your engine..

 

Twisty

[smiller]

It makes perfect sense, he is using the motor in the way it was designed to be used, it will operate better and last longer when used in that way.

And get better fuel mileage as well. More than one owner of the six-speed bikes have noted better crusing mileage when they avoid dropping the engine speed too low by using sixth gear at sedate freeway speeds. For any number of reasons running at the lowest possible engine RPM for a given speed is not always desirable.