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Discussion Starter #1
I'm starting a new build, a 2000 Monster 900 and I want to remove the airbox. The problem is that the bike has no way to readjust the air-fuel mixture. I'm not sure if the ECU can be reflashed so I am thinking about installing a Bosch lambda sensor. This sensor has an output of between 0.2V (lean) and 0.8V (rich) with 0.45 optimal (probably around 13.1:1.)
My idea is to use that output to offset the TPS output to fool the ECU. TPS output is typically between 0.5 and 5 volts.
Any thoughts?
 

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You might not even need to change anything,
other then removing the airbox will likely reduce your power and make a lot more induction sound.

Bike likely has all the sensors it will ever need now.
 

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Give you an example: when I bought a Montesa in a crate (fuel injected) it came full restricted for riders in countries that are only allowed to ride 125's ... Instructions came with the bike to remove all the pollution extras (cat) and intake and exhaust restrictors (significant restrictors)

To get the bike to work right, all I had to adjust was the idle screw and let it idle until the fan kicked on. Bike worked great. ... still does (y) fuel injection rocks
 

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Discussion Starter #4
It doesn't.
It has air temp, oil temp, TPS, and the ECU knows RPM, engine position, and the amount of spark advance. I just finished a BMW R1100 that has an O2 sensor and it ran fine after removing the airbox because the ECU adjusts air/fuel by (I assume) looking at tha O2 sensor voltage.
Removing the airbox on my 1993 Supersport was a bit of a chore but since it has carbs, rejetting and raising the needles was all it took. Anyway I was thinking about something like 2 opamps, one for voltages above .45V and one for voltages below .45v. One would add to the TPS output the other would subtract.
 

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It doesn't.
It has air temp, oil temp, TPS, and the ECU knows RPM, engine position, and the amount of spark advance. I just finished a BMW R1100 that has an O2 sensor and it ran fine after removing the airbox because the ECU adjusts air/fuel by (I assume) looking at tha O2 sensor voltage.
...
(y)

forget about carb model bikes when you are working with a Fi bike, not the same world.

You just listed a whole bunch of sensors and if it has no O2 sensor, not sure how you will benefit from by adding one to "fool" the existing throttle position sensor,
doesn't even sound like you have a cat converter, it's a 20 year old bike.

Do you have any wiring schematics to show what you are wanting to fabricate?

"The problem is that the bike has no way to readjust the air-fuel mixture"
Sure it does,the ECU has control over the duration of the fuel injection.
 

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Discussion Starter #7
Since the tps has a 1:10 voltage ratio from zero to 100% (.5 to 5 volts) adding to those values will lean the mixture and subtracting from those values will richen the mixture in real time hopefully. True, I don't know the response time (lag) of the Bosch Lambda sensor which could be problematic unless it's possible to build in the voltage offset.
 

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Your TPS throttle position sensor can only sense how open the thing is to air. It can only go from idle (closed) to wot (open)

The fuel duration is controlled by a square wave digital electric pulse. That pulse can have a shorter or longer or earlier or later duration. The injector is an electronically controlled valve. They know the operating temperature of the motor and the most air it can intake, the fuel is the only thing to adjust in the absence of a cat converter that is going to necessitate an O2 sensor because you only want hot gasses going through the cat converter so you do fancy **** inside the exhaust to deal with that issue :| O2 sensor is just a fancy high temperature variable resistor.
If you want more fuel all of the time and could actually burn it, you could just make the hole in the injector bigger, that would do it.
 

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The high volume airbox on that bike was even advertised as a performance feature at the time :| maybe Ducati lied, maybe it is restrictive as all **** and holding the bike back from needing more fuel,
or maybe it does something to the intake flow that you will never get back again without it.
Best luck with that project.

Did you try running it with no filter in place yet? you can't get much less restriction then that short of not putting any air filtration on your engine at all which is great if it is an indoor bike, a boat or a snowmobile.
 

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I must agree WTF is making you want to pull the air box off after the the web footed factory spent all that time (Time is $) getting the air flow perfect. Now if it's all about the look and you don't give a shit about how it runs then more power to you. Do remember that the factories ran those crappy little pod filters until Yosh figured out that all that did was take the cool consistent air that was being fed to the engine from the air box and turned it into hot, fast moving air where the flow was dictated by where your legs are , what angle the bike was and the gods be with you if'n it started raining. Then again if that's the price for looking cool then I shall not judge. If I was building a '60's look do the ton Cafe bike that was for shows and sunny day rides then why not.

Cheers Mate :unsure:
 

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Don't "they" sell gizmos to do this already, without the need of an O2 sensor? Buy the power commander or bazzazz or whatever the brand names are, spend some time on a dyno, and be on your way? I'm guessing all the messing around trying to hack into the existing system with an add on sensor would take more time/money than an afternoon on the dyno. And you'd have to to tune your cludge anyway.

In any case, I've had three Ducatis with that basic engine and have ridden each one of them with no airbox lid. The intake was painfully loud at.. was it 4500rpm? To the point I replaced the airbox lids on each one of them. Might be better with no airbox at all, but the point is don't downplay how loud the intakes can be on those things.

As for how fast a sensor can respond, when I've worked with calibrators at Ford, they can tell which cylinder is misfiring by looking at the sensor data.

Push the easy button and make an appointment at your local dyno shop:
 

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Who came up with the loony idea that a tiny air filter can replace a crankcase breather system that was designed to dump oil residue and compression blow-by into an air box, that just happens to be in a vacuum state at the time. It's a lop-sided V-twin, it has to breath. That filter plugs up and your engine performance is going to go for a **** your oil consumption will increase and it's going to piss oil all down the back of your motor.
Dumb idea unless you replace it after every race.
 

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This is yours?
I don't think that's his bike. The 900 uses different belt covers and the slave for the clutch is on the other side of the engine. Back in the day I could have made an educated guess on what that is, but I've forgotten too much shit.

In fact I don't think that's a 2000 Monster frame either.

That's a 750 (Super?) Sport me thinks....

Brad Black would know... oh BRAAAAAAAaaaaaddddddddd....

EDIT: Yeah.. for a fuel injected bike the thing that air filter is connected to looks a lot like a carb...

Edit of edit: Well duh. I did a little stalking and I was wrong. That IS his bike. But I was also right, it IS a 750 Super Sport. He has a thread here on it. I posted there.

So I guess you meant it was another one of his bikes. My bad. Anyway, I wouldn't be getting too wound about the filter on the crankcase, it's on top of the factory breather, same way a lot of earlier bikes were done back in the day. Hell, I did a similar thing on my roundcase.

As long as we're going off the rails here, pulling significant vacuum in your airbox seems a bit counter-productive. If the breather system depends on vacuum in your airbox, why would ram induction be a good thing?
 

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Discussion Starter #18
Thanks guys!!
That is my 750 SS (1993) but my other Duc is a 2000 900 Monster!
U B 1 astute Duc observer!
 

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You will love it if you are brilliant with the right computer software and internet savvy and trust that the aftermarket maps built into it are at least as good as the factory ones.
  • Each Power Commander Unit includes a built-in microprocessor and a base map for your motorcycle. Updated base maps are available for download from the PowerCommander.com website.
You can learn to tune fuel injection by altering the maps on a PC laptop computer program :cool: or if it messes things up just unplug it. Hope you have a laptop, it would suck to use a desktop.

... and a dyno, gonna need one so you know if you improved anything.
 
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