2004 R1150RT Wideband O2 Sensor Project (and AF-XIED for BMW)

Interesting point. At 49 degrees throttle there is 10 degrees more advance. I wondered about a second spring to increase resistance at 50 degrees.

The GS uses a different coding plug. I will have to use that some time and see how the advance plots.

Good stuff. These Spark-Advance/TPS/RPM graphs really get inside the brain of the Motronic.

If this is true, would it make the GS's different coding plug irrelevant?

Since the 1150 GS has different heads, cams and intake manifolds I believe there ARE differences in the VE (fueling) and Spark Advance tables. I plan to put a GS Coding Plug in my bike to see if there are any obvious Spark Advance differences.

What I was getting at with my comment is that I see several ways to adjust the fueling of the 1150 but I see no real way to adjust timing. Timing looks like a very dynamic matrix that you might change by swapping coding plug but not be able to effectively adjust by several degrees to a new value. For instance you can use a Wideband O2 to adjust closed loop fueling 4% richer or use a powerfommander to shift fueling but I don't see a way to adjust timing by 3 degrees at 5000 RPM with 50 degrees of throttle.

When I get a chance I will plot the 1150 GS plug. Then at least we will know the landscape.

It is also worth mentioning (even though I didn't plot it) that the dwell angle is very dynamic and changes somewhat differently from the advance curve. So the dwell time is variable based on TPS and RPM.

I for one, and I'm sure there are many others, that would love to see what the coding plugs do.

I know mine runs best on 91 octane gas, with the steptoe jumper, and it prefers the fancy plugs over the Autolite AP 3923s or whatever they are (single spark 2001). I suspect it is a bit richer with no CCP (which is how it came to me, I'm the second owner). It pings the same if I use mid grade gas whether I have the steptoe jumper on or not.

Thanks for all your hard work.

Tim

Have you seen Poolside's - Timing Adjustment How-to? It's not a dynamic change, but may allow you to shift the curve.

Keep up the good fight!

Let me pile on the thanks, and accolades Roger, great info!

I fully retard my HES plate a while ago to try and reduce the pinging I get with low octane fuel in the summer months, it really made difference that I could tell in the pinging, but I do feel like I lost some low end 'snap' from the engine.

Yes, I did see it. Quite an ingenious way to set the static timing.

Looking at the scatter-plots a few steps back and given that the timing varies from 5 degrees or so (at idle) up to almost 45 degrees of advance (at high rpm and middle throttle), I don't feel I know enough to make a shift of the whole curve.

However, a richer mixture does burn faster (I'm 6% richer than stoic at the moment) so it may be that I have advanced the point of peak cylinder pressure somewhat (chart of flame speed below). So I guess one could argue that I should retard the timing curve a bit since I've richened the mixture. Or maybe I should just accept a bit of advance and some additional part throttle power that I've gotten from sliding the dotted line to the left (second chart below).

Thanks. Any idea how many degrees you moved the timing by rotating the plate the way you did?

In the spirit of a picture is worth a thousand words, I've added a block diagram of the Motronic MA 2.4. This is my interpretation from research, the data I've taken throughout this thread and some deduction. I believe it to be a good-fit, functional representation of how the Motronic does it's job as a fueling and spark computer. As I find errors, I'll correct the diagram. (e.g. I don't know if there is a cold oil temperature, spark timing adjustment.)

Next I plan to post other diagrams showing how the Wideband O2 mods of this thread affect the system, as well as diagrams of how the PowerCommander and Techlusion interact with the Motronic MA 2.4. Eventually I'll add all four diagrams with a PDF link.

Before going to the diagrams of the Wideband modication, here is a view of the differences between the Open Loop and Closed Loop fueling.

Open Loop fueling starts with the TPS and HES signals and proceeds through adjustments for air temperature, barometric pressure, etc., proceeding to a fuel pulse being injected into the engine (ignoring the Adapt box for a minute).

Closed Loop fueling is a software program that begins with an Open Loop fuel pulse but then quickly uses measured Oxygen from the exhaust (the O2 sensor) to determine whether the mixture is richer or leaner than the target set by the O2 Sensor (switch). With a bit of trial and error, it locks into a range of fuel pulses that alternate between being a bit rich and a bit lean. The Closed Loop program is an aggressive "enforcer" of the mixture specifed by the O2 sensor. In a stock system that mixture is a lean 14.7:1 (for gasoline).

The Closed Loop program also has another activity which is to compare (the Compare box) the Closed Loop result with the Open Loop calculation. Over time, if these fuel pulses are different, the Closed Loop program "teaches" the Open Loop program some adjustments (the Adapt box). This means the Open Loop program gets corrections that can take into account: fuel type (e.g. E10 or gasoline), fuel pressure, air filter restrictions, fuel injector contamination, and throttle body, valve & cylinder accumulations. A weakness of the 1150 Motronic is that it treats both cylinders equally, which means we have to manually balance (left and right cylinders) the air (TB and valves) and fuel (injector cleaning and matching).

The diagram below can give an idea of which engine modifications will have a long-term effect on engine performance and which will be "learned out" by the Motronic's Closed Loop program.

My objective with the Wideband O2 project was to leave the many functions of the Motronic intact even while richening the overall mixture.

Before posting the next few diagrams, I spotted a function that I'd originally left off the Motronic diagram that is relevant to any fueling modifications that disable the Motronic's Closed Loop operation (1150 Motronic MA 2.4). If you look back at the previous two charts, they have a "Limp" function in the final fueling decision box.

The Limp box is the final step in Open Loop fueling, just after Adapt values have been applied. The Limp function as I have measured it (plot below) expands the variation of Open Loop fueling to a 10% variation. That is twice the amount of mixture variation that occurs in Closed Loop. The full post was here, Open Loop fueling variation. Although there is speculation that the Limp-Home function uses is a rich mixture, the measurements say that it runs 5% richer than and 5% leaner than the fuel table cruising target of 14.7:1.

What that means on an 1150 is that if you disconnect the O2 sensor and run a Powercommander, Techlusion, 3.5 Bar pressure regulator or BoosterPlug as an Open Loop fueling enhancement you can count on the Motronic to vary the fueling in a 10% range, like the plot below.

The next post will be a block diagram of the Wideband O2 system.

I read somewhere ( likely here) that the plate gives about +/- 5 degrees of adjustment.
I retarded it as far as possible, and began using 91 octane ( minimum), the pinging stopped, but in that same time period, our daytime temps went from 100 degrees, to about 60, so not sure which factor played the largest role.

My gut guess is the higher octane fuel, and the cooler temps.

Here is the block diagram showing how I've installed the Innovate Motorsports LC-1. The stock Narrowband O2 sensor has been removed, and in its place the LC-1 is installed. With months of measurements under my belt, I'm now confident that the Motronic functions the same with this sensor as it does with the stock sensor, it just programs and enforces a richer mixture.

Looking at the diagram you can also see that I've boosted the fuel pressure. This is an optional enhancement. When you shift the O2 setting from Lambda = 1 (stock) to Lambda = 0.94 as I've done, if you do nothing else the ADAPT box in the diagram will learn, over time, how much it needs to adjust the fueling to get the L=0.94 result. It takes time to adapt but eventually it does. Every pulse it sends out would become several percent longer.

The other option is to give the Motronic a headstart. One way is to add something like a BoosterPlug. It tells the Motronic the air is 20C colder and that results in a 6% richer mixture. The Motronic then has less adapting to do and gets to the final result faster.

The option I choose was to boost the fuel pressure by an amount that was equal to the shift in Lambda (plus an amount for E10 fuel) so that the Motronic would have almost no Adaptation work. (Fuel Pressure balances Lambda shift.) That means two practical things: as soon as you fire up the Motronic it's in the right ballpark; and every cell of the fueling table has been corrected (every pulse is affected by the increased fuel pressure), versus the coarser correction of the Adaptation process.

It seems like I've made a lot of measurements and tests to arrive at a simple solution for mixture enrichening but a side benefit is that a lot was learned about how the Motronic does its job and I've got a good confidence that the LC-1 implementation is compatible and that the Motronic is fully functional and operating as intended by the designers, just richer.

Tomorrow I'll add a block diagram for a Powercommander and Techlusion implementation.

EDIT: THIS EXPLANATION IS INCORRECT. PLEASE LOOK FURTHER INTO THE THREAD FOR A CORRECTED EXPLANATION. The error was due to an omission in the PC III Installation document that has since been discovered. Further, I have been in touch with Dynojet who have provided good detailed answers to some questions on the connection of their Wideband sensor to the Motronic that is not in any of their documentation.

Another way to add fueling to an 1150 (or 1100) is by using a PowerCommander III, block diagram below. This product includes a Wideband O2 sensor and an Add-On Fuel Table computer. It is a standard product, that can easily be added to an 1100 or 1150. Many believe that it is necessary to "Dyno Tune" the Powercommander after installation, but you could richen the mixture without having to go to that expense.

One reasonable way to use the PC III would be to install it along with its Wideband O2 sensor, use the included software to program the O2 sensor Lambda to 13.8, and fill in the fuel table with 6% everywhere, perhaps tapering off toward the high RPMs and high TPS angles. In this mode it would be similar to the LC-1 and somewhat easier to install.

With the O2 sensor programmed to 13.8, the Powercommander claims to operate its own proprietary Closed Loop program (see the shaded Closed Loop area in the second chart). That said, major parts of the Motronic are disabled when the PC III is installed, particularly the Adaptive ability. Powercommander makes no claim of Closed Loop adaptation within its module. Also, the Limp function of the Motronic is enabled when the O2 sensor input is disconnected. This means the pulse stream going into the PC III will have the 10% variation I wrote about a couple posts back.

The PC III looks pretty straight-forward to install but you do have to disconnect the O2, add two connectors to each injector, and install a piggy-back onto the TPS connector. So I would say it's fairly invasive to the Motronic system--if that matters to you. The PC gets its throttle position information from the TPS piggy-back but doesn't seem to have a TPS learn function like the Motronic. The PC III gets its RPM information from the injectors by measuring the frequency of fueling pulses. That works well but during Overrun Fuel Cutoff, the PC III doesn't have an RPM input. I think that might be a nit, but I mention it.

At its list price of $495.95, it's about three times the cost of an LC-1 but it is a Plug and Play solution. In terms of software, it's not clear to me whether the PC III has the logging capability of the LC-1 which I see as an important diagnostic tool. All the AFR charts of this thread have been made using that capability. It does come with a good suite of software for populating and managing the fuel tables should you wish to adjust them.





A further note on using the PC III for richening:

I mentioned that a simple way to use the PC III would be to program the Wideband O2 that comes with it to (say) 13.8:1 and fill in the fuel table with 6% (maybe tapering to a lower number at the high RPMs and high TPSs). However, 6% is only the right number if you're running pure gasoline.

Since I haven't seen any documentation on the PC III's Closed Loop capability and haven't measured it; and since the Motronic's Closed Loop ability (and therefore its Adaptation capability) is disabled by a PC III; I believe that the fuel table should have 10% added for motorcycles that run E10 fuel. That would be 4% for E10 and (say) 6% for the richer Lambda setting on the Wideband O2.

Another method for richening the mixture is through the use of a Dobeck Engineering product. I'm aware of a couple: one disables Closed Loop (Techlusion) and the other allows Closed Loop in part of the RPM range (Electronic Jet Kit). Both products use the same technical approach of monitoring the injector electrical pulse but not intercepting it. By measuring the time between injector pulses and their inection-on-time, the Dobeck technology can cleverly approximate the Load and RPM of the motorcycle. Neither product employs a Wideband O2 sensor like the LC-1 or PC III (although a gen 4 version does use a Wideband O2, I don't see it listed for the 1100s or 1150s).

The rider can then add fuel (lengthen the pulses) using three/four rotary dials (or plus/minus buttons) that allow different amounts of fuel to be added in cruise, acceleration or WOT. For me, the challenge of this approach is you can't specify how much fuel to add with a concrete setting (e.g. you can't specify 4% more than Closed Loop), and their is no Closed Loop monitoring of the result of the adjustment. However, with skill, it can be made to work--provided that Closed Loop is disabled. With Closed Loop disabled, the fueling additions are made to the Limp Home pulse train with its 10% fueling variation that I showed a few posts back.

Looking at the block diagram below, the Narrowband sensor gets connected to the Techlusion but there is no indication in the documentation that suggests the O2 sensor signal is used to calculate the fueling addition:

Hi Roger, great thread! Just came over from the Pinging thread. It would be nice to know if the OPEN loop adaptation (+/- 10%) is also disabled by the PCIII wideband. My understanding is this is exactly what is disabled with the older non-wideband PCIII when you also use an O2 eliminator. SInce the PCIII Wideband does have a plug for the stock O2 sensor wiring harness, you gotta wonder just what it does.

However you do raise an important point, on the GS + wideband PCIII, or any other bike running without a connected narrowband O2 but using O2 simulator. That is what if any ability does the remaining hybrid system have for E10? I am guessing none. But all gas in my area seems to be e10 so maybe that point is moot.

Another thought, my car is DI (335xi), and you have to code injectors before replacing them (system ID essentially), it would be nice if there were a way to model each injector for response times and so forth on the GS. I know the PCIII can do individual cylinder mapping in advanced mode, I wonder if there is any benefit in looking at that capability. Obviously the wideband does not see each exhaust pulse (the more modern systems do actually, by time windowing the O2 sensor output) but the fuel tables for each cylinder can be tweaked and then the wideband in closed loop would I guess blanket the whole thing and adjust globally.

Great stuff here.

Thanks for the feedback and comments. I've read and re-read the PCIII installation manual and intructions. It's not that the PC disables Adaptation it's more that without a valid O2 signal, it can't adapt.

Looking at it from the PC viewpoint it doesn't want the Motronic to adapt because the PC wants to be able to add fuel without being countermanded by the Motronic's adaptation.

I'm told the widebands are fast enough to look at individual exhaust pulses but am sure that neither the PC or Motronic are set up for this nor are they fast enough.

My experience with this is that 4-6% more fuel, open and closed loop make a great-running 1150. Either PCIII or LC-1 can do the job but they have different pluses and minuses.

I've been doing some further research on the Powercommander III for Oilheads and now have a much different view of how the PC and Motronic work together. My prior view that the PC didn't drive the Motronic's O2 sensor input was wrong and was due to a lack of documentation. But that said, here is an update for those interested:

I've heard from Dynoject and although I'd like some further clarifications, I don't think I'll hear more. The product was designed nearly 10 years ago and as you would expect the designers have moved on.

" the testing was done so long ago I may not be able to answer your question thoroughly."​

The BMW Powercommander III USB Wideband is essentially a Wideband Commander coupled to a Powercommander III USB.

The essence of what I've heard fro Dynojet is:

"The connection to the stock ECU narrow band input is tied to our Wideband sensor. We are able to offset the narrowband signal based on our wideband input."​

This is how the Innovate LC-1 works, although the LC-1 is a later, better performing design with data logging capability.

The BMW Powercommander and Motronic runs closed loop and develops Adaptation values everywhere the Motronic would on its own. That's because the Wideband signal, converted to narrowband format, is "Always connected". The shaded area on the PC fuel map (see photos several posts back) is just a guess on PC's part about where the Motronic is in closed loop.

"The highlighted area is what we have interpreted as the closed loop area of the stock ECU."​

I have many measurements that show the closed loop area of the Motronic is up to 62.5% throttle and up to 6250 RPM. I think we should expect that it is closed loop everywhere below those numbers.

I did some digging and found letters from Dynoject to Harley forums where there was a clamor for this capability. Here is part of what the design manager wrote:

"Let us start with why the BMW uses a wide band O2 sensor as part of the unit. The bike already has a "closed loop" circuit as part of the OEM injection system. It does not "auto map" the entire rpm/throttle position range of the fuel map. Generally speaking, the closed loop system only adjusts the fuel curve below 40% throttle. Above that the system is "open loop". The new Wide Band BMW unit only controls the stock "closed loop" area. Outside of that the bike is mapped in the normal fashion, on the dyno.

We would actually prefer not to maintain the closed loop section. Due to the design of the OEM injection system it is not possible to bypass it as we do with other models. Closed Loop systems are not the "magic" that most people believe they are. There are a number of problems that keep it from being the best choice for high performance applications."​

This all means that the PC III for USB works very differently on an Oilhead than on any other motorcycle most Dyno tuners work on. It also means that the WOT "pulls" aren't likely to provide an optimal tuning since most dyno tuners don't seem to understand the interaction with Closed Loop Adaptation Values. There's no reason that they should be familiar since this product works differently than most every other PC they would work with.

With this information, it is now pretty clear to me how the Powercommander and Motronic work together. My plan is to update the block and show a recommended fuel map for implementation. I am a lot more positive on the Powercommander as a tool now than before. It can be implemented on the majority of BMW Oilheads with NO Dyno tuning.

If anyone reading this would like to loan me a PC for a couple weeks I'd like to run some tests. In the meantime I'm going to try and buy one used. Then later I'll resell it, all set up for installation.

Earlier in this thread I presented an incorrect explanation of how the Power Commander III USB with Wideband O2 operated when integrated with the Motronic MA 2.4. The reason for this error was an omission in the Power Commander installation manual for R1150RT. Here is the correct explanation, please refer to the diagrams at the end of the thread.

The Power Commmander III with Wideband O2 for BMW R1150 and R1100 is actually two different functions in one package. One function is that of the Power Commander III USB an Add-On Fuel matrix of values according to RPM and TPS. The second function is much like that of the Innovate Motorsports LC-1. Rather than recapitulate the Add-On Fuel function you can read about it here: Power Commander III USB.

The second function, Wideband O2, functions just the same as an LC-1 Wideband O2 controller. You can read about that in detail earlier in the thread. In short, you replace the stock Narrowband O2 sensor that has a fixed transition point at 14.7:1 AFR (actually Lambda = 1, meaning that theoretically all the oxygen has been consumed) for a Bosch LSU 4.2 Wideband O2 sensor which has a programmable transition point. By selecting a Lambda value less than 1, the Motronic will automatically richen the mixture in the Closed and in the Open loop fueling calculation. I'll rephrase that: if you drop Lambda to 0.94 the Motronic will run Closed Loop at 13.8:1 which is 6% richer than stock 14.7:1. Then through the magic of the Motronic's Adaptation Values capability it will also add fuel to all Open Loop fueling calculations after a "learning" period.

The "learning" period takes some time and is not quite perfect because you have to drive your motorcycle at steady throttle for enough time in Closed Loop at a range of throttle openings and RPMs for the Motronic to "learn" the full adaptation map. It is likely that there are fewer Adaptation Values than cells in the Base Fueling Table of the Motronic, which means that there is likely a coarser correction. But I've measured it, and Adaptation works effectively, it just takes a while. The bigger the shift in Lambda that you're making, the longer it seems to take to "Adapt".

There is a way around the "learning" time. In short, find a way to either a) add a percentage of time to the pulse coming from the Motronic; or b) increase the fuel pressure so that the pulses coming from the Motronic deliver a percentage more fuel than stock. Since the Innovate Motorsports does not have an Add-On Fuel map I added a Fuel Pressure regulator and boosted the fuel pressure. However, if you use a PC III USB, you can add the fuel through the fuel table function.

Looking at the sample Add-On fuel tables below, if you fill in the fuel matrix with a 6% addition in every cell at 60% throttle and below, and then reduce to 4% more fuel at 80% throttle and 2% fuel at 100% throttle you will have a sound starting point. Note that this approach acknowledges the great work that BMW has done in their design of the Base Fuel Map in the Motronic; it just adds a proportional percentage to account for the amount of richness you want to add. I'm sure this seems like a simplistic use of the Add-On Fuel function of the PC III but it will work and you won't need to add a BoosterPlug or Fuel Pressure regulator.

I'll end with a short comparison of LC-1 and PC III. Both are technically sound methods for controlled richening of the Oilhead's mixture, leading to much better driveability and a bit more power in the mid-band (2000-5000 RPM) which it achieves by moving up the AFR vs Power Curve earlier in the thread. (There will not be an increase in WOT horsepower because the BMW fuel tables are already near Best Power Mixture there.)

Advantages LC-1:
--Lower cost: $170 for the LC-1, $395 for PC III (although I've seen PC III for $285)
--Calibration function for the Wideband O2 sensor
--Datalogging of the realtime stream of O2 readings
--AFR gauge included in purchase price. It is an add-on for the PC III.

Advantages PC III:
--Plug & Play: The PC III has all the connectors you need to plug it in out of the box. For the LC-1 you need to wire your stock O2 sensor connector and also power leads to its cable.
--Built in Add-On fuel capability. If you use the LC-1, you either wait for Adaptation, add a BoosterPlug which shifts fueling a fixed 6% or, as I did, increase the fuel pressure. A good fuel pressure regulator costs around $100.

RB

I've been doing some more research on the Power Commander so I'd like to update the Notes section but can't go back to edit it. Here are the notes with updates, 5) and 6):

Notes
1) I am trying to get a PC III w/Wideband but have not run one yet.
2) The fuel table on the PC III allows you to enter percent increase/decrease. Typical injectors have a 1 mS dead (on/off time), I don't know if the dead time is taken into account by the PC III.
3) At 7250 RPM the injectors fire every 8.3 mS. The longest injection pulse that I've seen is 8.2 mS. This points out that you can't add 5% to the longest pulses with making them longer than the frequency of rotation in some cases. (However, the vast majority of the time injection pulses are less than 4 mS.)
4) I don't think there's a problem but I can't tell how the PC III responds to Overrun Fuel Cutoff when no pulses occur (i.e. the PC III isn't getting any engine speed info during that time.)
5) Because the Powercommander gets its +12V from the injectors/fuel pump and since the fuel pump goes off after a couple seconds, Dynojet recommends hitting the starter button before the fuel pump cycles off.
6) The Powercommander DOES take injector dead-time into account when adding/subtracting fuel.

An update and some new info:

Lately I've moved my Lambda setting from 0.94 to 0.92 which is another couple percent richer. I did this because I noticed that just as the bike was finishing warm-up (while riding) I liked the cruise performance just a bit better than once it went Closed Loop. The biggest difference between a minute before to after Closed Loop is a few percent more fuel. I'm not sure just where I'll stop adding fuel.

There are a couple IC engine performance curves I've found that you might find interesting. Although NOT specifically for an Oilhead, interesting nonetheless.The first is HP vs AFR at various power levels:


The second is flame front speed as a function of mixture (note that it is Fuel Air ratio not AFR). This shows pretty clearly that as you richen the mixture, you speed up combustion. It looks to me to be the equivalent of 2-3 degrees more advance for an AFR of 13.8 compared with 14.7, at 3000 RPM. At 6000 rpm it might be 4-5 degrees if I'm doing the math right. Because of this effect I have been paying close attention to any hint of knock. There doesn't seem to be any probably because even though the timing advances some, knock resistance of richer mixtures is better.



So the bottom line is that when you richen the mixture several percent you're probably getting a triple benefit: a bit more torque from the extra fuel, a bit more torque from the more advanced (relatively) timing, and better efficiency due to better running and therefore into higher gears several hundred RPM sooner than at 14.7:1.

I figured out how to get Excel to add two Stock Dyno runs to the same chart so I'm reposting.

As I mentioned earlier in the thread, I realized several months ago that a GS-911 can be used as a personal Dynomometer. The key things you have to know are the vehicle's weight including rider (~800 lbs.) and aerodynamics (Cd=0.66, Frontal Area 8 sq-ft), gear ratios, and rear tire diameter (25.59" for PR2 in motion). You log the GS-911 to a data file, import it into Excel, run some math on the numbers and you have Torque, Horsepower and Acceleration. Working out how many feet/second of velocity are created per RPM in a gear is tedious but not difficult (0.01956667 for 4th gear).

It has been my belief based on the feel of my 2004 R1150RT that it has gained torque in the lower RPMs from running Closed Loop at 13.5:1 and fuel pressure at 52 psi. Spend some time looking at the charts below. The Excel chart is a scatter plot of 6 test runs that I took in 4th gear, no wind, 3 in one direction on the highway, 3 in the opposite. Some runs were better than others but I used them all. There are significant torque gains below 3500 RPM, especially between 2000 and 2500--this tracks my driving experience. My RT produces about 55 lb-ft at 2500 RPM compared to 45 lb-ft on Ron's sample. Note: The numbers I measured are actually 5% higher but, as with a Dyno, I reduced them by a factor of 0.956 to account for weather conditions.

Between 3000 RPM and 5000, my bike accelerates at about 12 ft/s². Anything over 10 ft/s² gives you reasonable acceleration. In fourth gear that requires 48 lb-ft of engine torque, the curves on my RT show that at 2000 RPM. There are also gains at higher RPMs.

While I believe my data is accurate, the one thing I would say is that I was careful to get the run prepped for low RPMs by running along at idle in 4th or 5th gear, then crank open the throttle. I did not run quite to the Rev Limiter, choosing to let go of the throttle at around 7000 RPM. So my numbers might be a bit better due to the care of low RPM starting but I don't think that explains it all.

Enjoy the curve, I've got some more coming.



Stock bike from Ron Hankison's web site.

http://www.r1150rts.com/DynoData/Dyno_004b.htm