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Old 12-17-2009, 05:57 PM   #1
DakarBlues OP
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BMW F800GS engine tuning

Did someone come up with serious engine tuning for this great bike?
Even something like a new map to smooth out the engine?

BMW 800 GS has the potential of being THE bike.
I road tested it (quite briefly I admit) and the vibration at highway speed is a nuisance.
I am sure it's possible to hoist that engine to the performance level of a KTM 990 without affecting gas consumption.

With its frugality, it's on its way to be the far away adventure bike of choice.
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Old 12-17-2009, 06:36 PM   #2
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if you open up the intake and exhaust you will need more fuel also, so you will take a mpg hit. I am really surprised there are no tuning options for this motor.
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Old 12-17-2009, 09:02 PM   #3
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Quote:
I am sure it's possible to hoist that engine to the performance level of a KTM 990 without affecting gas consumption.
Yes its possible but it would be alot of work, it would cost, you'd also lose fuel consumption and reliability. 15-20hp might not sound like much but when your trying to mass produce it and make it bolt on so people dont complain about the price its a big ask and id say thats why none's done it.

eg. CBR1000RR 180hp kit cost about 1200 us and that again in labour to fit it all.
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Old 12-17-2009, 10:15 PM   #4
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Of all the things I might be tempted to toss money at with respect to this bike the engine is not one of those things. It is near perfection IMO. The mapping on mine seems to be perfect. I have never felt like I needed more power or smoother throttle response in the adventure mode. Sure, my Duc 998 would leave it for dead on the tarmac, but so what?

Just a non-issue as far as I am concerned.
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Old 12-17-2009, 11:17 PM   #5
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I agree with tmex, I just wish it wouldn't redline at just over 110 MPH.

Can you turbocharge it? Is it even possible? I've seen a turbo on a CBR600 so it should be possible.
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Old 12-17-2009, 11:30 PM   #6
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Well, you can add turbo to a F800s, so it should be possible to add it here too, since it's almost the same engine
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Old 12-18-2009, 05:30 AM   #7
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Quote:
Originally Posted by josh9399
I agree with tmex, I just wish it wouldn't redline at just over 110 MPH.

.
In a 55 mph zone?
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Old 04-26-2010, 11:01 AM   #8
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Quote:
Originally Posted by MookieBlaylock
if you open up the intake and exhaust you will need more fuel also, so you will take a mpg hit. I am really surprised there are no tuning options for this motor.
Sorry, man, this simply is not the case. I've rejetted two KLR650's that I was running UNI air filters and Two Brothers exhaust on. If you open up air intake and open up exhaust flow without increasing fuel intake then you'll be running extremely lean: loss of power, overheating, pop-pop-pop, etc.... Now, if you open up air intake, open up exhaust flow, and also increase fuel intake to match, then what you've effectively done is improved power AND fuel economy. The engine will only burn what you provide it or allow it to have. It's not like we're forcing or pushing more air into the cylinder, rather allowing more air to come in. If you're allowing too much air to come in and not enough fuel: LEAN. If you're allowing too much fuel to come in and not enough air: RICH. If you're providing the correct mixture of air and fuel to the cylinder: IT WILL RUN PERFECT - regardless of exhausts and air filter. As long as the mixture is at the stoichiometric ratio of 14.7:1. The engine will only burn what you allow it or provide it. On both of my KLR650's, after I properly tuned the fuel air mixture to match what the cylinder needed, I noticed improved power and throttle response while maintaining the highest fuel economy, if not improving that as well.

Now, regarding the F800GS. I am running a UNI USA air filter and Leo Vince carbon exhaust. I am only assuming that the engine management computer increased the amount of fuel being injected into the mixture in order to compensate, but who knows? There is no hard evidence that the computer on this bike will do this. I do know that I'm pop-pop-popping down the road, which indicates a lean condition. This is due to the increased heat build-up in the exhaust system that the lean condition creates. This increased heat in the exhaust manifold causes some of the gases in there to ignite: POP POP!

http://en.wikipedia.org/wiki/Air-fuel_ratio
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The Griz screwed with this post 04-26-2010 at 11:18 AM
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Old 04-26-2010, 11:47 AM   #9
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I agree with your post above Griz, but will add a few things.

Yes the F800GS will compensate for a more free intake and exhaust to a point. It does have an oxygen sensor and a learning fuel map.

Base idle and closed throttle decel are NOT compensated by the F800GS but rather on a fixed fuel map.

All of them pop some on decel and this is much louder with aftermarket exhausts at least partially because the exhaust noises are usually much less muffled.


If power is all that one cares about then lambda (14.7 : 1 by mass) is not what you are looking for, you are looking for a somewhat fuel rich mixture.

This will be helpful to exhaust valves, tend to foul spark plugs, suck from a hydrocarbon and carbon monoxide emissions standpoint, destroy the cat, and reduce fuel economy, but will increase HP slightly
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Old 04-26-2010, 12:04 PM   #10
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Quote:
Originally Posted by JoelWisman
I agree with your post above Griz, but will add a few things.

Yes the F800GS will compensate for a more free intake and exhaust to a point. It does have an oxygen sensor and a learning fuel map.

Base idle and closed throttle decel are NOT compensated by the F800GS but rather on a fixed fuel map.

All of them pop some on decel and this is much louder with aftermarket exhausts at least partially because the exhaust noises are usually much less muffled.
Good to know Joel! Thank you!


Quote:
If power is all that one cares about then lambda (14.7 : 1 by mass) is not what you are looking for, you are looking for a somewhat fuel rich mixture.

This will be helpful to exhaust valves, tend to foul spark plugs, suck from a hydrocarbon and carbon monoxide emissions standpoint, destroy the cat, and reduce fuel economy, but will increase HP slightly
Exactly!! Me? I'm looking for 14.7:1.
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Old 04-26-2010, 07:49 PM   #11
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Seems pretty easy to me:
http://www.powercommander.com/powerc...dl=213&yr=2009
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Old 04-27-2010, 09:32 AM   #12
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Quote:
Originally Posted by The Griz
Good to know Joel! Thank you!



Exactly!! Me? I'm looking for 14.7:1.
If you have an AFR 14.7:1 up on top, then you are heading for a very short engine life. Better try 13:1 .
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Old 04-28-2010, 03:27 PM   #13
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Quote:
Originally Posted by JoelWisman
I agree with your post above Griz, but will add a few things.

Yes the F800GS will compensate for a more free intake and exhaust to a point. It does have an oxygen sensor and a learning fuel map.

Base idle and closed throttle decel are NOT compensated by the F800GS but rather on a fixed fuel map.

All of them pop some on decel and this is much louder with aftermarket exhausts at least partially because the exhaust noises are usually much less muffled.


If power is all that one cares about then lambda (14.7 : 1 by mass) is not what you are looking for, you are looking for a somewhat fuel rich mixture.

This will be helpful to exhaust valves, tend to foul spark plugs, suck from a hydrocarbon and carbon monoxide emissions standpoint, destroy the cat, and reduce fuel economy, but will increase HP slightly
Sounds like this is the reason for the the slight stumble, when slowly trying to ease over things just off idle. If it is, than doesn't sound like there is much that can be done about it.
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Old 04-28-2010, 05:38 PM   #14
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Quote:
Originally Posted by itsatdm
Sounds like this is the reason for the the slight stumble, when slowly trying to ease over things just off idle. If it is, than doesn't sound like there is much that can be done about it.
(quoting what I said about no fuel adaption at idle)

actually what I said was much to simplified.

There are three types of adaption, "additive", "multiplicative" and "extrapolated".

Addative adaption occurs on the fly as soon as the engine is warm. The F800GS uses a standard narrow band slow oxygen sensor and it is too far back in the exhaust to be useful without causing idle to hunt and peck all over the place. Addative adaption occurs once the sensor is warm at just above idle all the way to just short of wide open throttle (wot).

Multiplicicative adaption occurs over time and is remembered and incorporated as a conversion factor of the base fuel map. Multiplicitave is remembered from start up cycle to start up cycle and changes slowly over miles and large fractions of an hour of running.

The F800GS does use multiplicative adaption for idle fuel mix as well as part throttle fuel mix.

Lastly there is extrapolated adaption. The F800GS's O2 sensor is not capable of measuring fuel mixtures that are significantly different then lambda, and yet for a variaty of reasons INCLUDING emissions you want a pretty rich mixture at WOT. As such, the F800GS engine management computer enriches the mixture at near full throttle through WOT by a certain percent. This enrichment is based on the modified multiplicitive fuel map and is therefore called extropolated adaption.

The idle fuel mix is adapted but not well, it takes it some time to be optimal when the energy or oxidizer content of fuel changes. When I have gone from oxygenated to unoxygenated fuel it took about 20 minutes for the o2 sensor to start crossing.

The real reason for jerky transitions from idle is a lack of acurate sensors such as an air mass sensor or at least MAP sensor and the fact that BMW has so far failed or does not wish to damp this transition with industry techniques.

My guess is that the snapy throttle sells bikes after a test ride to typical F800GS customer, even though it is sub optimal off road in technical stuff.

As for stumbles going from part throttle to idle. This shouldn't happen if everything has had time to adapt to fuel and conditions but does on some bikes and I have no idea why.
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Old 04-28-2010, 04:46 PM   #15
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