Forums > Maintenance > Surging

I've got an '03 RT and it can surge something fierce.  Personally, I like the surging.  It's like a young horse who just wants to go faster and keeps testing the reigns.

The reason that the bike surges is that there is a lot of horsepower flowing through two big pistons and the computer is constantly searching for an efficient burn as defined by its programming.  The computer does this via microscopic adjustments to the air/fuel mixture at the injectors, based on feedback from the oxygen sensor in the exhaust pipe under the engine.

In theory these microscopic mixture adjustments shouldn't be felt.  In practice, in the real world, of course they are.

The best way to minimize feeling the surging is to keep the bike in a very high state of tune.  For a home tuner, this is done by keeping all of the valve lashes precisely balanced, and the vacuum through the throttle-bodies precisely balanced.

Noticed that I used the word balanced and not "set".

Think of the computer as an electronic instrument tuner and the engine as a two-stringed instrument.  The computer only has one ear located in the exhaust stream after the two exhaust streams are combined.  The computer only has one ear and is listening to the combined pitch of two strings.  The computer is looking for a perfect pitch from plucking both strings.

If you don't have the two sides of the engine balanced, the computer will be constantly plucking and adjusting both strings at the same time, but it will never find a perfect pitch.

Get both sides of the engine humming together like the Andrews sisters, and you won't have any surging.

99% of professional wrenches do not have the time to mess around with your engine like a stringed instrument.  They'll achieve a minimum level of spec, close it up, and call it good.

There is a special feeling that comes out of a balanced engine that isn't surging and is singing like the Andrews sisters.  To get there you're going to have to take yourself, or pay a a good wrench to do it in his home garage on Saturday night.

I'm just saying . . .

C

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Another sunrise, These bright and crystal moments, Crow flies overhead.

Hey Sercher...

My R1100S surged noticably at first and of course BMW admits nothing. This has been discussed for a decade on the 'net and there are lots and lots of articles on it..... You can do somethign about it though. If you are mechanically inclined you can do some adjustments that will dramatically improve the smoothness... Best to make sure the bike is out of warranty first though...

In a nutshell:

1. Adjust the valves very carefully. This is easier then it sounds, especially if you have ever done it on a Japanese four cylinder with shim-under-bucket valves. The BMW is a breeze with the cylinders hanging out there in the wind. Buy a set of the proper feeler gauges (two of each size), get the factory manual or a Haynes/Clymer. Search the internet for "Oilhead Valve Adjustment for Dummies". The first time will take you a few hours, but after that it doesn't take much time. I check/adjust mine every spring when I take it out, and every oil change thereafter.
2. Sync the throttle bodies precisely. Once again easier then it sounds, but you should get a TwinMax to do this with (Google it). Search the internet for "Oilhead Throttle Body Synching for Dummies". I check/adjust mine every spring when I take it out.
3. If you want to go whole hog, then perform the ZERO = ZERO as described by the late Rob Lentini... Just Google it once again. It only needs to be done once.

Doing this will significantly balance the cylinders and improve the responsiveness and smoothness of the engine.

As a final tweak install a Techlusion R259 box to improve the fule injection. Once again Google it. Many places seel these and they are easy to install and set up.

Hope that helps!!

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Shaun , 2001 BMW R1100S (The Yellow Hornet!)

I have owned an example of every type of oil head and they all surge!  The later twin plug 1150s seemed to surge the least and the new 1200s don't seem to surge at all.

I bought a new 1100GS from the first batch manufactured for Europe (a 1994 model) and wrote a whole document for the BMW club in the UK about the issue.  I was amazed how long it took for the fix..............about 10 years!

It is true that careful setup can reduce the amount of surging but the simple fact is that it is a characteristic of the bikes.  In my case the worst one I had was a '99 1100 GS, closely followed by a '00 1150 GS.  The best one was an '04 Rockster.  My recent 1200s show no sign of the problem.

You can get used to it and once familiar simply ride around it.  Try to forget the problem is there and you'll do just fine.

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Everyone is entitled to my opinion!

Boxer surging occurs for several reasons;

1- Valve lash out of spec. Carefully adjust valve lash. Absolute clearance is not as important as equal between valves.

2- TB Sync. While not as important as valve lash, it will help.

3- Vacuum leaks in the intake track. Check all clamps in the induction system. Remove and lube the orings to eliminate any air leaks.

4- Dirty TBs. The throttle bodies can get dirty and cause air flow irregularities. Clean your TBs thoroughly.

5- Spark plugs. I run Autolite 3923s with success. They aid starting, produce better fuel mileage and smooth the engine a bit.

6- Poor fuel. Be careful where you fuel.

7- Dirty injectors. Add a bit of Techron to clean up the injectors.

Boxers delivered in the US run on the lean side of stoichiometric fuel/air ratio. Keep your boxer well tuned, fuel with quality gas and maintain your valve lash carefully.

I rountiely lug my boxer in higher gears at 2500 RPM in town commuting. I have no surging.

A late-model boxer will not surge if properly tuned.

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Dennis

Seacher,

All the above may or may not help.  The cause of surging is very simple.  Your bike is running too lean to meet strict EPA emission guidelines. You can tune it all you want, and that will only help if the surging problem is very mild.  However, it sounds like your surge is more severe and can't be tuned out. What is puzzling about surging is when you test the emissions using an exhaust gas analyzer, an oilhead (R1100 series motor) should be 1.5 HC +/- .5%.  However, some surging bikes read richer and surge, while others that are leaner don't.   The bottom line is your bike is too lean.  The fuel - air mixture needs to be moved closer to a stoichometric mixture. 

I have fixed surging on oilheads using two solutions.  The best way for an older R1100 series bike is converting back to the European open-loop standard with a Bosch potentiometer.   The other way is using a Techlusion device.  I've tested and used all the versions of the Techlusion products and even co-authored an article in BMWON with Paul Glaves on this subject. For older oilheads, a Bosch potentiometer or Techlusion will fix the problem.

However, your bike is not designed to use the Bosch potentiometer, since all were made world-wide to run closed-loop.  So, your best bet is to try the Techlusion R259 designed to run on closed-loop bikes.  This product has eliminated or reduced about 90% of all surging on almost all BMW oiheads  that have severe surging problems by extending the duration the fuel injectors stay open to richen the air-fuel mixture.  They cost about $250 and are well worth buying vis selling your bike.

However...a word of caution.  This device can be considered a defeat mechanism to the EPA certification.  This is the primary reason why I believe BMW can't endorse.  However, many if not most BMW dealers sell these devices and even install.  

The down side is a Techlusion device will increase your fuel consumption dropping MPG by 3-5 miles per gallon.  However, they are adjustable and very safe to use.  If it fails, your bike starts to surge again since it returns to a lean mixture.  

I've used a Techlusion on an RT for over 100,000 miles and recently pulled the heads.   The valves and heads look great.  

Kenk said:

 

I have fixed surging on oilheads using two solutions.  The best way for an older R1100 series bike is converting back to the European open-loop standard with a Bosch potentiometer.   The other way is using a Techlusion device.  I've tested and used all the versions of the Techlusion products and even co-authored an article in BMWON with Paul Glaves on this subject. For older oilheads, a Bosch potentiometer or Techlusion will fix the problem.

However, your bike is not designed to use the Bosch potentiometer, since all were made world-wide to run closed-loop.  So, your best bet is to try the Techlusion R259 designed to run on closed-loop bikes.  This product has eliminated or reduced about 90% of all surging on almost all BMW oiheads  that have severe surging problems by extending the duration the fuel injectors stay open to richen the air-fuel mixture.  They cost about $250 and are well worth buying vis selling your bike.

My UK '99 1100GS had no cat and did have the pot you refer to - it was still pretty bad!  Tried all things including richening the mixture, changing the plugs, of course always ensuring that it was in good tune - in my experience there is no real cure (though I did not try any of the after market fixes).  I just found that I got used to it and would ride around it.  Only now the with my new 1200 has the problem gone, thoguh I did find the twin plug 1150 to behave 95%. 

I also had the same issue with some cars in the early '90s in the UK.....just as you ease of the throttle in heavy traffic the car would try to accelerate!

The oil head surging is well known about in the industry and it is not just BMW.............most of the jap bikes have had similar troubles.  I note, however that Ducati have always been perfect in this respect.  I had a '90 851 that ran uust as though it had carbs and I understand that that was a given...............so it does beg the question why can't all manufacturers get it tuned in right? 

Of course BMW never had trouble with the K bikes??

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Everyone is entitled to my opinion!

Kenk said:

 

I have fixed surging on oilheads using two solutions.  The best way for an older R1100 series bike is converting back to the European open-loop standard with a Bosch potentiometer.   The other way is using a Techlusion device.  I've tested and used all the versions of the Techlusion products and even co-authored an article in BMWON with Paul Glaves on this subject. For older oilheads, a Bosch potentiometer or Techlusion will fix the problem.

However, your bike is not designed to use the Bosch potentiometer, since all were made world-wide to run closed-loop.  So, your best bet is to try the Techlusion R259 designed to run on closed-loop bikes.  This product has eliminated or reduced about 90% of all surging on almost all BMW oiheads  that have severe surging problems by extending the duration the fuel injectors stay open to richen the air-fuel mixture.  They cost about $250 and are well worth buying vis selling your bike.

[/quote]

My UK '99 1100GS had no cat and did have the pot you refer to - it was still pretty bad!  Tried all things including richening the mixture, changing the plugs, of course always ensuring that it was in good tune - in my experience there is no real cure (though I did not try any of the after market fixes).  I just found that I got used to it and would ride around it.  Only now the with my new 1200 has the problem gone, thoguh I did find the twin plug 1150 to behave 95%. 

I also had the same issue with some cars in the early '90s in the UK.....just as you ease of the throttle in heavy traffic the car would try to accelerate!

The oil head surging is well known about in the industry and it is not just BMW.............most of the jap bikes have had similar troubles.  I note, however that Ducati have always been perfect in this respect.  I had a '90 851 that ran uust as though it had carbs and I understand that that was a given...............so it does beg the question why can't all manufacturers get it tuned in right? 

Of course BMW never had trouble with the K bikes??

My 2004 Ducati ST3 surged terribly for the first year.  Ducati recognized the problem and warranted all 2004 ST3s with a new 2005 ST3 ECU.  Totally fixed the problem.  

On the issue of your UK GS surging. If your bike has no CAT and O2 sensor, it most likely isn't a lean-fuel closed loop surging problem we commonly refer to on the  US bike.  Open-loop bikes have no 02 sensor to provide a signal to the ECU when the air-fuel mixture strays from predetermined stoichometric mixture.  I don't doubt your bike is having surging like symptoms.

Kenk said:

On the issue of your UK GS surging. If your bike has no CAT and O2 sensor, it most likely isn't a lean-fuel closed loop surging problem we commonly refer to on the  US bike.  Open-loop bikes have no 02 sensor to provide a signal to the ECU when the air-fuel mixture strays from predetermined stoichometric mixture.  I don't doubt your bike is having surging like symptoms.

Bikes without the cat (it was an option in Europe until the late '90's) do have a potentiometer - but this only sets the 'base' mixture.  The bike still adjusts the mixture according to inputs from the various sensors, temp, pressure, tps etc............all the bikes (inlcuding the 850s) - those with and those without cats have the problem with surging.  Some are worse than others, and yes a good tune can help it does not remove the problem.  Only with the twin plug 1150s did the problem start to get better and then the 1200 with even more sensors and a more detailed ECU removed the problem all together.

Interesting to hear about your ducati.............

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Everyone is entitled to my opinion!

Jonp said:

[quote user='Kenk']

On the issue of your UK GS surging. If your bike has no CAT and O2 sensor, it most likely isn't a lean-fuel closed loop surging problem we commonly refer to on the  US bike.  Open-loop bikes have no 02 sensor to provide a signal to the ECU when the air-fuel mixture strays from predetermined stoichometric mixture.  I don't doubt your bike is having surging like symptoms.

[/quote]

Bikes without the cat (it was an option in Europe until the late '90's) do have a potentiometer - but this only sets the 'base' mixture.  The bike still adjusts the mixture according to inputs from the various sensors, temp, pressure, tps etc............all the bikes (inlcuding the 850s) - those with and those without cats have the problem with surging.  Some are worse than others, and yes a good tune can help it does not remove the problem.  Only with the twin plug 1150s did the problem start to get better and then the 1200 with even more sensors and a more detailed ECU removed the problem all together.

Interesting to hear about your ducati.............

A bike without a CAT and 02 Sensor can't surge since the bike has no 02 sensor providing a signal to the ECU causing it to hunt for a correct air-fuel mixture.  There's good reason why Mark Dobeck from Techlusion connects the R259 to the 02 sensor and fuel injectors.  Unfortunately, disconnecting the 02 sensor on an 1150 series bike is not an option since the ECU went from 2.2 to 2.4....all worldwide were closed-loop.  His only real options are selling the bike, living with the problem or a Techlusion device.  Hundreds of BMW owners use them with great success.  

Kenk said:

A bike without a CAT and 02 Sensor can't surge since the bike has no 02 sensor providing a signal to the ECU causing it to hunt for a correct air-fuel mixture. 

Not to be rude, but oh yes it can...........as I said it is not only the O2 sensor that that gives a signal to the ECU to control the fueling.  The M2.1 (no cat or O2 sensor) operates with a CO pot that sets the basic mixture but the ECU also processes engine temp, engine load, intake air temperature and engine speed to determine fueling and spark advance.

The US is one of the smallest export markets for BMW, even little old England sells more BMWs than the US and as such you'll find that the experience gained here in the US is in fact a little bit limited.  If you look a little further afield you'll see that the surging trouble is well documented amongst all R259 series motors - those with and without cats.

The difference between US and the rest of the World spec bikes is pretty limited, obviously all the lens covers have to have a DOT sign as do the screens, the running gear is pretty much the same.  As for the motors we only get low octane fuel here in the US so the motor is set up a bit different on some models (slightly lower power as a result) and the dreaded charcoal cannister for CA (not fitted for any other markets)

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Everyone is entitled to my opinion!

Jonp said:

[quote user='Kenk']

A bike without a CAT and 02 Sensor can't surge since the bike has no 02 sensor providing a signal to the ECU causing it to hunt for a correct air-fuel mixture. 

[/quote]

Not to be rude, but oh yes it can...........as I said it is not only the O2 sensor that that gives a signal to the ECU to control the fueling.  The M2.1 (no cat or O2 sensor) operates with a CO pot that sets the basic mixture but the ECU also processes engine temp, engine load, intake air temperature and engine speed to determine fueling and spark advance.

The US is one of the smallest export markets for BMW, even little old England sells more BMWs than the US and as such you'll find that the experience gained here in the US is in fact a little bit limited.  If you look a little further afield you'll see that the surging trouble is well documented amongst all R259 series motors - those with and without cats.

The difference between US and the rest of the World spec bikes is pretty limited, obviously all the lens covers have to have a DOT sign as do the screens, the running gear is pretty much the same.  As for the motors we only get low octane fuel here in the US so the motor is set up a bit different on some models (slightly lower power as a result) and the dreaded charcoal cannister for CA (not fitted for any other markets)

We will have to agree to disagree.  Many bikes from all different makes are running overly lean to meet the strict EU and EPA standards.   These bikes display surging like systems, since they too are running overly lean.  With my Ducati ST3, it ran very lean under 4000 rpms.  However, since my Ducati has no 02 sensor, the lean condition was very constant...like it is on all the Harleys or Japanese bikes without 02 sensors.  This condition is very different and much less irritating from the surging BMW oilhead.  If you want to call that surging...fine.  I was one of guy that helped Techlusion determine the proper setting for the R259 back in 2001.  Techlusion makes a product for just about every motorcycle since most are running overly lean.  I am not employed by Techlusion or use one today.  My only surging bike is an older R1100RT, coverted to open-loop with a Bosch pontentiometer.  It's 100% surge free now.

However, this thread shouldn't be about other bikes.  It's about Searchers bike and I stand by my advice.  

[/quote]

We will have to agree to disagree.  Many bikes from all different makes are running overly lean to meet the strict EU and EPA standards.   These bikes display surging like systems, since they too are running overly lean.  With my Ducati ST3, it ran very lean under 4000 rpms.  However, since my Ducati has no 02 sensor, the lean condition was very constant...like it is on all the Harleys or Japanese bikes without 02 sensors.  This condition is very different and much less irritating from the surging BMW oilhead.  If you want to call that surging...fine.  I was one of guy that helped Techlusion determine the proper setting for the R259 back in 2001.  Techlusion makes a product for just about every motorcycle since most are running overly lean.  I am not employed by Techlusion or use one today.  My only surging bike is an older R1100RT, coverted to open-loop with a Bosch pontentiometer.  It's 100% surge free now.

However, this thread shouldn't be about other bikes.  It's about Searchers bike and I stand by my advice.  

[/quote]

Without any doubt, what you say about Searchers situation is on the mark. 

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Everyone is entitled to my opinion!

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1994 K1100RS & 2005 Harley Electra Glide