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Reasons for poor fuel economy?


King Herald

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King Herald

Bit of a long post, but I’m trying to include all the info in that I can:

 

1997 1100r, totally stock, U.K. model, no O2 sensor but has an idle pot. 110,000 miles on it now. 
 

It alway had the awful surge at low rpm, and no amount of tuning, adjusting valves, TPS,  balancing throttle bodies etc would fix it.

 

During covid lockdown I decided to explore how to sort it out. New injectors were fitted, but made absolutely no difference to the surging.

 

I pulled out the beige cat code plug, which made it really smooth at low speeds, but run really rich and ‘soft’ at higher rpm, and the plugs were black and very sooty. I put it back in. 
 

I adjusted the idle pot from one end of the scale to the other, made no difference to surging. 

 

I then decided to pull the throttle bodies, clean them thoroughly and do the hero to zero throttle stop adjustment. That made no difference. So I reverted to the more traditional way to set them. Same again, no difference to surging. 

 

At some point during the above shenanigans the fuel consumption has dropped to 45 miles per U.K. gallon, so 37 per US gallon. I’m sure I was getting closer to 55 or even 60 before I did all the messing about with the bike. At one point in the past  I got to 190 miles before the fuel light came on. 
 

My last adjustment was playing with cat code plugs, and I eventually jumpered it to what is the US spec, telling the Motronic that it has an O2 sensor, which it hasn’t, but it makes the bike run perfectly, I can crawl along at idle, then open the throttle and it pulls away as smooth as silk. But that didn’t change fuel consumption at all. Putting the beige plug in and running through a tank of fuel gives the same 45mpg.
 

Any suggestions what could have caused the increased thirst? The bike is great in every respect other than fuel consumption.
 

I have a Yamaha Bulldog, 1100 V twin that gives a minimum 65mph gallon no matter how hard I use it, and that has carbs.

 

IMG_5606.thumb.jpeg.031c2e4b47ef931a89aa264232e32820.jpeg 

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dirtrider
4 hours ago, King Herald said:

Bit of a long post, but I’m trying to include all the info in that I can:

 

1997 1100r, totally stock, U.K. model, no O2 sensor but has an idle pot. 110,000 miles on it now. 
 

It alway had the awful surge at low rpm, and no amount of tuning, adjusting valves, TPS,  balancing throttle bodies etc would fix it.

 

During covid lockdown I decided to explore how to sort it out. New injectors were fitted, but made absolutely no difference to the surging.

 

I pulled out the beige cat code plug, which made it really smooth at low speeds, but run really rich and ‘soft’ at higher rpm, and the plugs were black and very sooty. I put it back in. 
 

I adjusted the idle pot from one end of the scale to the other, made no difference to surging. 

 

I then decided to pull the throttle bodies, clean them thoroughly and do the hero to zero throttle stop adjustment. That made no difference. So I reverted to the more traditional way to set them. Same again, no difference to surging. 

 

At some point during the above shenanigans the fuel consumption has dropped to 45 miles per U.K. gallon, so 37 per US gallon. I’m sure I was getting closer to 55 or even 60 before I did all the messing about with the bike. At one point in the past  I got to 190 miles before the fuel light came on. 
 

My last adjustment was playing with cat code plugs, and I eventually jumpered it to what is the US spec, telling the Motronic that it has an O2 sensor, which it hasn’t, but it makes the bike run perfectly, I can crawl along at idle, then open the throttle and it pulls away as smooth as silk. But that didn’t change fuel consumption at all. Putting the beige plug in and running through a tank of fuel gives the same 45mpg.
 

Any suggestions what could have caused the increased thirst? The bike is great in every respect other than fuel consumption.
 

I have a Yamaha Bulldog, 1100 V twin that gives a minimum 65mph gallon no matter how hard I use it, and that has carbs.

 

 

Morning   King Herald

 

With any CCP that tells the engine it has an o2 sensor that will usually lower the fuel economy on a non-o2 sensor equipped 1100 Ma 2.2  motorcycles.  

 

With a CCP that tells the engine that it has an o2 sensor it will then disregard the factory idle pot & go to a full rich idle that carries up into the low/midrange. This is also why adjusting the idle pot doesn't work or change anything  (it isn't even looked-for, let alone used)

 

But that idle & low throttle richness does clean the light-throttle engine surging up pretty darn good.

 

It's a trade-off, if you want your fuel economy back then either remove that jumpered CCP, or go back to the stock CCP, then adjust the idle pot towards the richer side until the surging is just about gone for most light throttle riding but your fuel economy improves a bit.  (very fine line here)

 

The other thing to look for is, as your light throttle surging gets better that probably ALSO increased the idle RPM, so if you do a lot of stop & go riding re-set the idle RPM back to where it was with the correct CCP & correctly adjusted  idle pot.

 

Bottom line: if you want your light throttle surging gone then you will pay a price with reduced fuel economy. You won't notice a big fuel economy hit if you ride a lot of high speed or freeway (throttle plates opened up past light throttle)  but for lower speeds or stop & go riding you will notice a hit in fuel economy. 

 

Just keep in mind that: Any CCP configuration that grounds pin 87 (hooks pin 87 to pin 30) will deactivate the idle trim pot, so if you want a usable (adjustable)  idle trim pot then pin 87 must be open.  

 

Your best bet is to probably completely remove the CCP jumpers, then unplug the idle trim pot, then ride the motorcycle for a while. This should give you the least amount of surging (& highest idle RPM). Then once you establish a baseline, plug the idle trim pot back in & adjust it for the same high idle & lack of surging that you had without the idle trim pot plugged in.

 

Then ride the motorcycle & every few days adjust the idle trim pot for a leaner idle mixture until you just get a slight amount surging back  (this is the base to be adjusted from).

 

Once you have a base with just a little light throttle surging then you can tweak it in the rich direction until you start to see a noticeable decrease in fuel economy this is your fuel economy limit.

 

So just leave it there or set it a little richer to remove the surging & live with the decreased fuel economy. 

 

Riding in traffic, stop & go, lighter throttle usage, commuting, etc  (IF) you want the least amount of surging, that then takes the richest fueling, so you pay the price in decreased light throttle fuel mileage. 

 

Also, remember, as you add light throttle fuel richness that increases the engine idle RPM, higher idle RPM's can lower fuel mileage in stop & go riding conditions as sitting at idle you are still using fuel but getting 0 miles per gallon. The higher the idle RPM the more fuel it uses without adding any travel miles. 

 

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King Herald

Morning DR,

thanks for the info. I actually tried the whole idle pot adjustment scenario long before I tried the latest CCP setup. I measured resistance across the idle pot, with it on the bench, and it was at the factory setting, which I found somewhere on these pages. I basically adjusted it from one end of the spectrum to the other a little at a time over a week or so, and it didn’t  appear to make even a slight bit of difference to how the motor runs. That was with the factory beige CCP still in place. 
 

I even traced the idle pot wires back to the Motronic box to check they actually had connectivity. All seemed okay there. 
 

And I’ve also reverted it totally back to factory setting, fairly recently, the surge returned, maybe even worse than originally,  but the economy was still poor. 
 

Strange thing is that the spark plugs look a healthy light brown colour at the moment, and I put new ones in a few months back, thinking that may help. 
 

I’ve swapped back and forth between e5 and e10 ethanol fuel and that doesn’t make any difference to fuel economy. 

 

Is there any chance the Motronic could be faulty, seeing as it doesn’t appear to see the idle pot? 
 

ps. Fitting the new ‘upgraded’ injectors did no more than raise the idle to 1400 rpm. Which makes sense, more fuel, better spray pattern, better combustion etc. But the supplier reckons that has never happened before. 
I put the old ones back in a few months back, but nothing changed when I did that, no even the idle. 

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dirtrider
25 minutes ago, King Herald said:

Morning DR,

thanks for the info. I actually tried the whole idle pot adjustment scenario long before I tried the latest CCP setup. I measured resistance across the idle pot, with it on the bench, and it was at the factory setting, which I found somewhere on these pages. I basically adjusted it from one end of the spectrum to the other a little at a time over a week or so, and it didn’t  appear to make even a slight bit of difference to how the motor runs. That was with the factory beige CCP still in place. 
 

I even traced the idle pot wires back to the Motronic box to check they actually had connectivity. All seemed okay there. 
 

And I’ve also reverted it totally back to factory setting, fairly recently, the surge returned, maybe even worse than originally,  but the economy was still poor. 

 

Strange thing is that the spark plugs look a healthy light brown colour at the moment, and I put new ones in a few months back, thinking that may help. 
 

I’ve swapped back and forth between e5 and e10 ethanol fuel and that doesn’t make any difference to fuel economy. 

 

Is there any chance the Motronic could be faulty, seeing as it doesn’t appear to see the idle pot? 
 

ps. Fitting the new ‘upgraded’ injectors did no more than raise the idle to 1400 rpm. Which makes sense, more fuel, better spray pattern, better combustion etc. But the supplier reckons that has never happened before. 
I put the old ones back in a few months back, but nothing changed when I did that, no even the idle. 

Morning  King Herald

 

The beige CCP should leave terminal 87 ungrounded so you should have idle trim pot (Idle Valve) authority & have the ability to control idle Co fueling.

 

So, first thing is take a BIG swing at it & completely disconnect the idle trim pot. This should remove the surging & give good running engine but probably somewhat poor fuel economy. If that does then you know your idle trim pot should be able to adjust the idle & low speed fueling (if it is working correctly). 

 

As for poor fuel economy IF the idle trim pot is not the issue then----- 

 

Make sure the air filter element is flowing properly, not just look clean but actually flow enough air. Paper filter elements can look clean but have swelled up paper pores if they were extremely wet at one time or another.

 

Make sure the oil temperature sender is tracking correctly, if your R doesn't have a temperature gauge you might not notice the oil temp sender not reading correctly.  

 

Make sure the AIT (Air Intake Sensor) on top of the air filter box is hooked up & the terminals are making good CLEAN contact. I have see a few that the connector would plug in OK but had a loose terminal fit (do a terminal drag test if you can find some new terminals)

 

Do not warm the engine up before riding as that typically eats into your overall fuel economy (engine running but no motorcycle movement equals 0 miles per gallon)

 

If the weather is cold in your area now & you are running a heavy based engine oil then the engine pumping looses will be high resulting in lower miles pe gallon (especially on the R bike as the oil probably never gets very hot in cold weather).

 

If you are riding in very cool or cold weather then hold off on chasing poor fuel economy until the weather warms up as chasing poor fuel economy in cold weather is a lot of guessing with no way to properly verify. 

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King Herald

Morning Dr, I shall have a go removing the idle pot, and put the stock beige CCP in place, see what happens. Then I shall try adjusting the idle pot again, see if I messed something up last time I tried it. 
 

The air temp sensor is in good condition, plug fits good and tight, air filter has been changed a few times over the years. 
 

The fuel economy is a touch worse in winter, but not markably so. I use some semi synthetic 10/40 in winter but summer I go back to regular 20/50 mineral oil. 
 

I’ve often thought of blocking off one oil cooler during the winter months, just wrap silver foil around it, under the cover, to get the engine temp up, does anybody ever do it? I have no engine temp gauge on this model. When I start it I use high idle for about 30 seconds, then ride off immediately. 

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dirtrider
44 minutes ago, King Herald said:

Morning Dr, I shall have a go removing the idle pot, and put the stock beige CCP in place, see what happens. Then I shall try adjusting the idle pot again, see if I messed something up last time I tried it. 
 

The air temp sensor is in good condition, plug fits good and tight, air filter has been changed a few times over the years. 
 

The fuel economy is a touch worse in winter, but not markably so. I use some semi synthetic 10/40 in winter but summer I go back to regular 20/50 mineral oil. 
 

I’ve often thought of blocking off one oil cooler during the winter months, just wrap silver foil around it, under the cover, to get the engine temp up, does anybody ever do it? I have no engine temp gauge on this model. When I start it I use high idle for about 30 seconds, then ride off immediately. 

Morning King Herald

 

Blocking part of the oil cooler off will help engine heat a little but not a lot as the oil thermostat probably isn't allowing much oil flow through the coolers anyway.  

 

Most of the low oil temperature in cold weather is due to all the exposed alloy crankcase (very large heat sink).

 

When it comes to playing with the idle trim pot your friend here is a complete quick disconnect, that reverts it to full rich at idle & low throttle openings (as long as pin 87 isn't grounded to pin 30). 

 

If you have the idle trim pot set to mid adjustment or leaner then you should see a difference between the trim pot plugged in & not plugged in.  

 

The air temp sensor is in good condition, plug fits good and tight--- Just because the connector plug is a tight fit doesn't necessarily mean the terminals are making resistance-free contact. 

 

You can also remove the oil temperature sensor then clean it, then put it in the freezer overnight then next morning put your ohmmeter on  it & track the resistance as it warms up. The BMW 1100 uses an (NTC) thermistor so the resistance goes up as the temperature goes down. 

 

The resistance is not linear & seems to vary a little when trying to test (probably due to meter hook-up resistance) but here is something you should be somewhat close to___

 

0°  C should be around 5.5K +/- ohms    (freezing)

40° C should be around 1.25K +/-ohms 

100° C should be around 190 +/- ohms (boiling water)

 

Basically you want to see the resistance change in the direction shown above & not have any holes or opens as the sensor temperature changes (as it warms up).

 

If the sensor doesn't test open then it is probably good as those (NTC) thermistors are pretty solid so they typically work right or they don't work at all. 

 

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King Herald

Morning Dr, 

CCP plug and idle pot removed, it runs good and rich at low speeds, but  is also rich at higher rpm and feels sluggish and non responsive. 
 

Beige CCP put it, idle pot re-installed, very jerky at low speeds, awful, so I’ve wound the idle pot in to almost full richness. Clockwise until it reads 200ohms, so I at least have a data point. It’s much better at low speeds than with it was, just a touch of surging. I’ve only done a few miles in it, so I’ll do some more today and get a better feel.  Maybe wind that screw out a bit if it feels smooth enough riding.  
 

I read in one of your posts on another thread that winding the idle pot screw in enriches the mix, but in the past I thought clockwise weakened it,  not sure where I picked that up.

 

I’ve just filled the tank so I’ll run through a tank of gas and see if there is any difference in consumption.

At some stage I shall pull the oil temp sensor, and freeze it, just to check. 
 

Do you have any numbers for measuring the air intake temp gauge? 

 

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dirtrider
1 hour ago, King Herald said:

Morning Dr, 

CCP plug and idle pot removed, it runs good and rich at low speeds, but  is also rich at higher rpm and feels sluggish and non responsive. 
 

Beige CCP put it, idle pot re-installed, very jerky at low speeds, awful, so I’ve wound the idle pot in to almost full richness. Clockwise until it reads 200ohms, so I at least have a data point. It’s much better at low speeds than with it was, just a touch of surging. I’ve only done a few miles in it, so I’ll do some more today and get a better feel.  Maybe wind that screw out a bit if it feels smooth enough riding.  
 

I read in one of your posts on another thread that winding the idle pot screw in enriches the mix, but in the past I thought clockwise weakened it,  not sure where I picked that up.

 

I’ve just filled the tank so I’ll run through a tank of gas and see if there is any difference in consumption.

At some stage I shall pull the oil temp sensor, and freeze it, just to check. 
 

Do you have any numbers for measuring the air intake temp gauge? 

 

Morning King Herald

 

That's a good sign, you now  HAVE  Idle trim pot (Idle Control Valve) authority so can play with idle & light throttle fueling richness.  

 

You want to weaken the idle control valve (ICV) signal to force richer. The ICV signal wire back to the Motronic is terminal #2 on the ICV.  So just monitor the voltage out of terminal #2 on the ICV, the lower the voltage the richer it should idle & fuel at light throttle. 

 

Just remember that unplugging the ICV makes it as rich as it can go so you want to trim the ICV #2 terminal output voltage lower to go richer & trim the #2 terminal output voltage higher to go leaner.

 

Also remember that with pin 87 grounded the Motronic won't look at the pin #2 voltage. 

 

The ICV controls the Motronic using voltage input not resistance so tracking the ICV with an ohmmeter will measure two ways  depending on IF you are measuring between terminal #2 & the ICV low (terminal #3), or measuring between  terminal #2 & the ICV high (terminal #1).   

 

Back when I (we in the USA) were doing a lot of work using the ICV to trim the (no CCP)  1100 Ma 2.2  light throttle fueling we didn't have access to the BMW factory ICV without paying big money (no E-Bay cheap parts back then) so we would make our own ICV using a 10 or 20 turn trim pot.  All our 1100 bikes were also o2 sensor equipped so we could easily switch back to the factory CCP, or swap in the better pink CCP using o2 sensor input.

It's kind or a trade off in the 1100R bikes (at least the ones that I owned or worked with). The pink CCP actually ran slightly richer/smoother at mid range up (with o2 sensor disconnected) but that was at the trade off of light throttle lean surging.

Removing the CCP (no o2 control) richened the idle & light throttle area, pretty well eliminating the light throttle surging, but that did soften the mid range somewhat.  

 

Ideally you would like to be able to run the pink CCP (with o2 input) but HAVE ICV authority at low throttle opening, unfortunately you can't have both. 

 

As a test,  you might try the CCP jumper that you show above but unplug the pin 87 leg as that might bring up a European fueling map that is closer to the pink CCP but still provide ICV authority.  (worth a test ride anyhow)

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King Herald
3 hours ago, dirtrider said:

Morning King Herald

 

That's a good sign, you now  HAVE  Idle trim pot (Idle Control Valve) authority so can play with idle & light throttle fueling richness.  

 

You want to weaken the idle control valve (ICV) signal to force richer. The ICV signal wire back to the Motronic is terminal #2 on the ICV.  So just monitor the voltage out of terminal #2 on the ICV, the lower the voltage the richer it should idle & fuel at light throttle. 

 

Just remember that unplugging the ICV makes it as rich as it can go so you want to trim the ICV #2 terminal output voltage lower to go richer & trim the #2 terminal output voltage higher to go leaner.

 

Also remember that with pin 87 grounded the Motronic won't look at the pin #2 voltage. 

 

The ICV controls the Motronic using voltage input not resistance so tracking the ICV with an ohmmeter will measure two ways  depending on IF you are measuring between terminal #2 & the ICV low (terminal #3), or measuring between  terminal #2 & the ICV high (terminal #1).   

 

Back when I (we in the USA) were doing a lot of work using the ICV to trim the (no CCP)  1100 Ma 2.2  light throttle fueling we didn't have access to the BMW factory ICV without paying big money (no E-Bay cheap parts back then) so we would make our own ICV using a 10 or 20 turn trim pot.  All our 1100 bikes were also o2 sensor equipped so we could easily switch back to the factory CCP, or swap in the better pink CCP using o2 sensor input.

It's kind or a trade off in the 1100R bikes (at least the ones that I owned or worked with). The pink CCP actually ran slightly richer/smoother at mid range up (with o2 sensor disconnected) but that was at the trade off of light throttle lean surging.

Removing the CCP (no o2 control) richened the idle & light throttle area, pretty well eliminating the light throttle surging, but that did soften the mid range somewhat.  

 

Ideally you would like to be able to run the pink CCP (with o2 input) but HAVE ICV authority at low throttle opening, unfortunately you can't have both. 

 

As a test,  you might try the CCP jumper that you show above but unplug the pin 87 leg as that might bring up a European fueling map that is closer to the pink CCP but still provide ICV authority.  (worth a test ride anyhow)


Afternoon DR, 

I have got the 87 leg unplugged now, just the 87a and 30 are linked. I’ve been out and ridden 40 miles today, in awful weather, a mix of town and country roads,  and I basically forgot I was in the ‘old’ mode that ran so rough at low speeds.
 

Fingers crossed something has improved in the fuel economy department. 
 

I have an awful/embarrassing feeling that when I did all the idle pot adjustments a couple of years ago I may not have had anything in the CCP socket, which means it wasn’t seeing the idle pot….. which would explain why nothing changed no matter how much I twiddled the screw…:4317:

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dirtrider
1 hour ago, King Herald said:


Afternoon DR, 

I have got the 87 leg unplugged now, just the 87a and 30 are linked. I’ve been out and ridden 40 miles today, in awful weather, a mix of town and country roads,  and I basically forgot I was in the ‘old’ mode that ran so rough at low speeds.
 

Fingers crossed something has improved in the fuel economy department. 
 

I have an awful/embarrassing feeling that when I did all the idle pot adjustments a couple of years ago I may not have had anything in the CCP socket, which means it wasn’t seeing the idle pot….. which would explain why nothing changed no matter how much I twiddled the screw…:4317:

 

Quote

I have an awful/embarrassing feeling that when I did all the idle pot adjustments a couple of years ago I may not have had anything in the CCP socket, which means it wasn’t seeing the idle pot….. which would explain why nothing changed no matter how much I twiddled the screw

Afternoon King Herald

 

Actually, without a CCP you SHOULD have had ICV function.

 

(NO CCP) means no pin (87) to (30) ground so ICV should have been active.

 

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King Herald
17 hours ago, dirtrider said:

 

Afternoon King Herald

 

Actually, without a CCP you SHOULD have had ICV function.

 

(NO CCP) means no pin (87) to (30) ground so ICV should have been active.

 


As a test,  you might try the CCP jumper that you show above but unplug the pin 87 leg as that might bring up a European fueling map that is closer to the pink CCP but still provide ICV authority.  (worth a test ride anyhow)

 

This is what I have now actually. 

I thought the action of the beige CCP was to tell the Motronic that I do have an idle pot installed? It connects 87a and 30 together. I thought I’d read that in one of Roger’s threads. 
 

It was a couple of years ago, I maybe have got it all wrong, I read so many articles on the subject over the years it’s overloaded my little brain. 
 

 

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dirtrider
33 minutes ago, King Herald said:


As a test,  you might try the CCP jumper that you show above but unplug the pin 87 leg as that might bring up a European fueling map that is closer to the pink CCP but still provide ICV authority.  (worth a test ride anyhow)

 

This is what I have now actually. 

I thought the action of the beige CCP was to tell the Motronic that I do have an idle pot installed? It connects 87a and 30 together. I thought I’d read that in one of Roger’s threads. 
 

It was a couple of years ago, I maybe have got it all wrong, I read so many articles on the subject over the years it’s overloaded my little brain. 
 

 

Morning King Herald

 

Pin (30) is the constant low (ground) so that is used for the low in any of the pin selections, pin (87) to pin (30) tells the Motronic NOT to look for an ICV. So with any CCP selection that grounds pin (87) to pin (30) you have no ICV authority.  

 

Your beige CCP connected pin (87a) to pin ( 30) so that one DID NOT connect pin (87) to pin (30) so with the beige CCP you should have ICV authority. 

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King Herald

We’ve had a week of non stop rain and floods here, so not done much riding and only just refilled the tank last night. Results are disappointing, I was hoping for a reasonable amount of extra miles after the tuning tweaks, but it hasn’t happened. After 170 miles I put 16 litres to fill it again, which equates to 40 miles per US gallon. A touch better than before but not as good as was hoped. 
I shall check the oil temp sensor some time this week. 

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3 hours ago, King Herald said:

40 miles per US gallon

FWIW, that seems about right for an 1100 with the mileage you have on yours (in my experience).

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dirtrider
3 hours ago, King Herald said:

We’ve had a week of non stop rain and floods here, so not done much riding and only just refilled the tank last night. Results are disappointing, I was hoping for a reasonable amount of extra miles after the tuning tweaks, but it hasn’t happened. After 170 miles I put 16 litres to fill it again, which equates to 40 miles per US gallon. A touch better than before but not as good as was hoped. 
I shall check the oil temp sensor some time this week. 

Morning  King Herald

 

You probably need to average out 4 or 5 tank fills to get a usable fuel mileage.

 

Is your odometer accurate? 

 

If you have replaced or messed with the  HES then make sure that your ignition timing is spot on. 

 

If you are using E-10 fuel (or alcohol containing fuel) that can vary bit in alcohol content. 

 

Otherwise put the OEM CCP back in, then trim your ICV to get the light throttle surging back, then average out a few tank fill-ups. That should give you best fuel economy as a baseline to judge against as you make future changes.  

 

 

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King Herald
3 hours ago, dirtrider said:

Morning  King Herald

 

You probably need to average out 4 or 5 tank fills to get a usable fuel mileage.

 

Is your odometer accurate? 

 

If you have replaced or messed with the  HES then make sure that your ignition timing is spot on. 

 

If you are using E-10 fuel (or alcohol containing fuel) that can vary bit in alcohol content. 

 

Otherwise put the OEM CCP back in, then trim your ICV to get the light throttle surging back, then average out a few tank fill-ups. That should give you best fuel economy as a baseline to judge against as you make future changes.  

 

 

 

Morning DR,

I use e5 exclusively in the BM, better quality fuel altogether, apparently. 


The setup I’m running now is the original CCP with the idle pot set to run almost as rich as it can go. After 80 miles I backed the adjustment out 2 turns and the low speed surge became noticeable. Not badly, but definitely a stumble when going on and off throttle at low speeds. I shall take it out 2 more turns and see how ridable it is, and run through another tank of fuel. 
 

I’m not too sure how accurate the odometer is, but the speedo does read about 5% high across the range, when compared to a GPS speed reading. 
 

I replaced the HES some 50,000 miles ago and I’ve checked timing at high rpm, with a timing light through the crankcase peek hole,  it is bang on the mark. I didn’t have the idle low enough to check the timing at slow speed. I had a plug out yesterday, the electrodes are a bit black and sooty but the centre ceramic is light brown. 

 

4 hours ago, 9Mary7 said:

FWIW, that seems about right for an 1100 with the mileage you have on yours (in my experience).

 

Yes, she just rolled over 111,000 miles yesterday, so no spring chicken. It’s also mid winter here, not much above freezing, which probably means richer running most of the time. 

 

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2 hours ago, King Herald said:

 

Morning DR,

I use e5 exclusively in the BM, better quality fuel altogether, apparently. 


The setup I’m running now is the original CCP with the idle pot set to run almost as rich as it can go. After 80 miles I backed the adjustment out 2 turns and the low speed surge became noticeable. Not badly, but definitely a stumble when going on and off throttle at low speeds. I shall take it out 2 more turns and see how ridable it is, and run through another tank of fuel. 
 

I’m not too sure how accurate the odometer is, but the speedo does read about 5% high across the range, when compared to a GPS speed reading. 
 

I replaced the HES some 50,000 miles ago and I’ve checked timing at high rpm, with a timing light through the crankcase peek hole,  it is bang on the mark. I didn’t have the idle low enough to check the timing at slow speed. I had a plug out yesterday, the electrodes are a bit black and sooty but the centre ceramic is light brown. 

 

 

Yes, she just rolled over 111,000 miles yesterday, so no spring chicken. It’s also mid winter here, not much above freezing, which probably means richer running most of the time. 

 

 

King Harold,

 

Question on E5 Fuel,  I thought reading my 1150rt manual, it recommended 95 octane fuel (manual is out in the cold right now). E5 is 87 Octane and 5% ethanol.  Could some of your surging and mileage from operating low octane fuel and the ethanol?  I am guessing the bike was designed prior to the heavy use of ethanol fuels 5% is low. We also run into a lot of issues here regular unleaded which is 5%-ethanol in small engines messing with rubber and plastic parts not designed for it.  

 

RF

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dirtrider
4 hours ago, King Herald said:

I use e5 exclusively in the BM, better quality fuel altogether, apparently. 


 It’s also mid winter here, not much above freezing, which probably means richer running most of the time. 

 

Afternoon King Herald

 

E-5 is better than E-10 so that shouldn't be your issue.

 

E-5 hurts your light throttle runability slightly but not nearly as much us riders here in the U.S. where our BMW motorcycles are equipped with o2 sensors to control fueling. 

 

Your slightly lower fuel economy (40mpg isn't that bad for an 1100) is more than likely due to this statement you made above____       "not much above freezing".

 

Colder weather really effects non o2 sensor motorcycles as they tend to base the fueling more on the engine & air temp sensors. Not to mention continually spinning transmission & final drive parts in very thick cold gear oil.

 

With a functioning o2 sensor it is all about closed loop so the fueling is only controlled by the o2 sensor when in closed loop operation.  So as long as the engine & intake sensors ALLOW it to go into closed loop then all it uses for fueling control is the o2 sensor feed back. As long as it stays in closed loop then it could care less about the engine sensors for fueling. It does look at the engine sensors as far as spark mapping goes in closed loop. 

 

Your BMW doesn't have an o2 sensor so all your fueling is based on engine RPM, throttle position (TPS),  and engine sensor input. The RPM  vs. Throttle Position basically tells the Motronic engine load. 

 

Personally, I would wait until warm weather to go after fuel economy as that will probably make more difference than anything you can do mechanically or CCP/ ICV wise. 

 

 

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King Herald
13 hours ago, Redfoxx said:

 

King Harold,

 

Question on E5 Fuel,  I thought reading my 1150rt manual, it recommended 95 octane fuel (manual is out in the cold right now). E5 is 87 Octane and 5% ethanol.  Could some of your surging and mileage from operating low octane fuel and the ethanol?  I am guessing the bike was designed prior to the heavy use of ethanol fuels 5% is low. We also run into a lot of issues here regular unleaded which is 5%-ethanol in small engines messing with rubber and plastic parts not designed for it.  

 

RF


I started to use  e10 when it first came out, as it’s 10% cheaper than e5, but it made no difference to the way the bike ran or the mileage. I’ve even tried different brands with no noticeable differences. 
 

12 hours ago, dirtrider said:

Afternoon King Herald

 

E-5 is better than E-10 so that shouldn't be your issue.

 

E-5 hurts your light throttle runability slightly but not nearly as much us riders here in the U.S. where our BMW motorcycles are equipped with o2 sensors to control fueling. 

 

Your slightly lower fuel economy (40mpg isn't that bad for an 1100) is more than likely due to this statement you made above____       "not much above freezing".

 

Colder weather really effects non o2 sensor motorcycles as they tend to base the fueling more on the engine & air temp sensors. Not to mention continually spinning transmission & final drive parts in very thick cold gear oil.

 

With a functioning o2 sensor it is all about closed loop so the fueling is only controlled by the o2 sensor when in closed loop operation.  So as long as the engine & intake sensors ALLOW it to go into closed loop then all it uses for fueling control is the o2 sensor feed back. As long as it stays in closed loop then it could care less about the engine sensors for fueling. It does look at the engine sensors as far as spark mapping goes in closed loop. 

 

Your BMW doesn't have an o2 sensor so all your fueling is based on engine RPM, throttle position (TPS),  and engine sensor input. The RPM  vs. Throttle Position basically tells the Motronic engine load. 

 

Personally, I would wait until warm weather to go after fuel economy as that will probably make more difference than anything you can do mechanically or CCP/ ICV wise. 

 

 

 

Morning DR, I shall continue to monitor it as the weather increases. What I’ve got now is the best it’s been for a long time, so hopefully the changes will improve more with the weather. I should do a full tune up some time soon, which might help even more. 
Thanks for the help. :18:

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Michaelr11
3 hours ago, King Herald said:

Morning DR, I shall continue to monitor it as the weather increases. What I’ve got now is the best it’s been for a long time, so hopefully the changes will improve more with the weather. I should do a full tune up some time soon, which might help even more.


Hello KH

 

I try to stay out of DR’s way. I would encourage you to complete a full baseline tune up. I would check the voltage set on the idle tps. Fuel mileage is very similar to tire life. It is very dependent on the rider and their ride style, and the riding environment of road and weather and gasoline. I ride a 2001 1100RT with more than double the miles on your 97. It is stock for USA, O2 sensor, no fuel modifiers, stock exhaust. I ride almost all two lane secondary and back roads in the hills. The pace is brisk, but usually 4th or 5th gear, mostly 4th. My fuel mileage is generally in the range of 44-46 mpg (US) during the winter, and 45-48 in the warmer weather once summer gasoline blend is in circulation. 

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King Herald
10 hours ago, Michaelr11 said:


Hello KH

 

I try to stay out of DR’s way. I would encourage you to complete a full baseline tune up. I would check the voltage set on the idle tps. Fuel mileage is very similar to tire life. It is very dependent on the rider and their ride style, and the riding environment of road and weather and gasoline. I ride a 2001 1100RT with more than double the miles on your 97. It is stock for USA, O2 sensor, no fuel modifiers, stock exhaust. I ride almost all two lane secondary and back roads in the hills. The pace is brisk, but usually 4th or 5th gear, mostly 4th. My fuel mileage is generally in the range of 44-46 mpg (US) during the winter, and 45-48 in the warmer weather once summer gasoline blend is in circulation. 

 

Hi Michael,

I’m a fairly slow rider, I rarely ever lean on the throttle particularly hard, and a lot of my riding is at lower speeds, around built up areas. Some long trips at highway speed would probably increase my economy but I’ve not really been touring since all the covid crap kicked off, for various reasons. 

I’ve done multiple tune ups in the last few years, set the TPS bang on the recommended voltage, tried it higher and lower in an attempt to cure surging. I’ve done multiple throttle body balances, using two different types of vacuum gauge devices etc.


I’ve also tried bigger valve clearances, having read that can help, but all it did was cause an awful lot of noise. 

I’ve just discovered today that I have the dreaded throttle body pivot wear, I can hear the left side tapping away, until I put my finger on the quadrant and then it stops. I doubt that would make any difference to fuel economy though. Just another thing to sort out.

 

I average just over 1000 miles a month, and with fuel prices in the UK about double what you pay stateside a few more miles to the gallon would be the final touch to what is my favourite ever motorcycle. :grin:

 

IMG_1727.thumb.jpeg.c71b852ef50b32e0675ac5fb85770de4.jpeg

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