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Old 07-31-2013, 03:00 AM   #1
Jonny955 OP
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Quick question for fuel map gurus...

Hi. Just a quick question because I am a bit confused.

The fuel mapping for the standard 990 takes into account the requirements for the catalytic converters in the two exhausts, right?

My understanding, rightly or wrongly, is that these cats require a richer mixture to control the heat because excessive heat (typical of a leaner set up) destroys them.

If the cans are replaced with non-cat types, such as Akras, KTM recommend changing to the 'Akra' map although many inmates run the standard map with these exhausts.

Question 1: Does the KTM Akra map use a leaner ratio than the KTM standard map because it does not need to take account of the requirements of the catalytic converters?

Question 2: If the KTM Akra mapping does not have to fight to support the cat and emissions requirements, should it be more efficient, bhp for bhp?

Thanks,

Jon
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Old 07-31-2013, 06:51 AM   #2
Jaimoto
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Hi Jon. FI noob here, but I can answer some of your questions

I think you get it wrong. AFAIK the cat needs very high temps to work, it's the excess of unburned mix that kill them. Even there is a secondary air system that injects air to help burn that extra fuel so it doesn't make it to the cats.

Quote:
Originally Posted by Jonny955 View Post
Question 1: Does the KTM Akra map use a leaner ratio than the KTM standard map because it does not need to take account of the requirements of the catalytic converters?
Akra map is richer than standard. When you install an aftermarket free flowing can, more air goes through the engine so it needs more fuel to keep a reasonable air/fuel ratio. That's the theory, not saying Akra maps are perfect.
And since there are no cats, the excess of unburned fuel can't do any harm to them

Quote:
Originally Posted by Jonny955 View Post
Question 2: If the KTM Akra mapping does not have to fight to support the cat and emissions requirements, should it be more efficient, bhp for bhp?
I guess it should. Since now you're burning more air and more fuel, you should be getting more hp. But I'm not sure if that happens, the general consensus seem to be that the Akra map injects too much fuel and you're dumping part of it.
What I do know is the Akra map helps a lot in throttle response and smooths the engine a lot. Since there are no changes in the ignition maps, we can deduct that a richer map like the Akra helps curing the jerky throttle.
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Old 08-01-2013, 03:14 AM   #3
Jonny955 OP
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Thanks for the response.

I guess I had it the wrong way around regarding unburnt fuel and heat to the Cats.

I'll be collecting my (2nd) KTM990 Adventure soon and it's already been fitted with the 2-1 Remus and KTM Akro mapping, which was apparently required to keep it under warranty with an aftermarket can.

I'm not heavy on the throttle so I'll benefit from a smoother map at low to mid-range.

There seem to be so many opinions on what works best, though. My last 990 (another 2012 model) had standard mapping and standard cans and was OK but the fuelling felt a bit harsh - that's not jerky, just harsh in terms of sounding very 'thuddy'. I put this down to the challenges KTM had to meet for emissions. Ridden carefully, it would return 49mpg (41.3 US) but normally about 46mpg (38.8 US). My mate has the 990R (same engine as the 2012 990) with Akros and Akro mapping. Riding like a dick, he gets about 42mpg (35.5 US) but I don't think he's tried riding any other way

Jon
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Old 08-01-2013, 05:56 AM   #4
DirtJack
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It's rather long now, but you might look at the 990 TuneECU thread and note the people who have done data logging and dyno work to track the effects of mapping changes.
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