Re-mapping the Mk4 (?) 690 motor.

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mangocrazy
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Re-mapping the Mk4 (?) 690 motor.

#1 Post by mangocrazy » Tue Oct 29, 2019 10:40 pm

I've never been very good with these Mk X, or Gen Y type nomenclatures, so... Anyway as far as I'm aware the model of KTM 690 single motor that I have is the latest that the factory have produced and (if rumours are true) the last one they will build. Of course this may well prove to be complete nonsense in a few months/years time, but at time of writing, this is what I believe to be the case.

The single cylinder KTM motor harks back to the late 1980s, when it was (I believe) a 550cc motor producing around 50 bhp. The current one is 690cc and produces a claimed 75 bhp in the R model. As the engine capacity increased, so did the reliance on electronically controlled fuel injection. The prospect of a 690cc single fed by carburettor(s) boggles the mind.

Up until the 2011 model year, the ECU could be modified by use of the readily available TuneECU program. The RC8/R models (are you listening Fatboy) likewise have their ECUs amendable by TuneECU. However after that date (and looming EU emissions restrictions) it all got a lot more complicated.

Current 690 engines (and I'm sure the same is true for all recent fuel-injected engines) have an open-loop and closed-loop map. The open loop can still be modified by dyno operators, and/or by bolting on a Power Commander, but the closed loop is a different matter. The closed loop operates at low rpm/throttle opening where most engines spend most of their life and in many cases is not easily modifiable. Power Commanders have no effect on the closed loop.

KTM (and probably most other manufacturers) run fuelling in the closed loop as lean as they dare, simply to meet emissions targets. Big singles suffer the most in this regime as the engine is entirely dependent on one power stroke, whereas 2, 3 or 4 cylinder engines can spread the load and smooth out the power delivery. If a single cylinder is running on the fine edge of lean fuelling you will feel it more than on any other engine configuration.

What this means in practice is that at light throttle openings or on a constant throttle, throttle response feels on a knife edge and is nearly always 'hunting', or giving jerky, inconsistent, off/on responses. The engine needs more fuel, can't get it and is running hotter than it would prefer to be due to lack of the right amount of a cooling inlet charge. Fuel consumption is miserly, but it's no fun trying to make your way through traffic with that kind of throttle response.

On the open road when you can get the revs up and open the throttle, it's far less of a problem, in fact it's pretty much non-existent. I suspect that the closed loop is where all the emissions runs are performed and are kept tightly controlled, whereas the open loop area of the map is more geared to performance under load. This is the area where Power Commanders are effective, but paradoxically are least required.

Anyway, that's the background. I'm about to start ringing around some dyno tuners and see what they can offer to fix the closed-loop fuelling (if indeed that's possible) and see if any more power is available at the top end (but to be honest that is the least of my concerns).

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#2 Post by fatboy » Fri Nov 01, 2019 7:05 pm

Heard you Graham !
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katie1
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#3 Post by katie1 » Sat Nov 02, 2019 6:24 pm

In case you don't have any luck, you could try the guys that remapped my Super Duke?

https://www.davewoodracing.com/

They're in Buckingham so it would be a bit of a trek but would be more fun on the way back :smt003
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#4 Post by Wally » Sat Nov 02, 2019 9:45 pm

If you went for a standalone ecu and a wideband o2 sensor rather than the usual cheaper narrow band sensor, it would just be a dyno tune for max performance as you could run as rich as you need.

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#5 Post by mangocrazy » Sun Nov 03, 2019 8:51 pm

Hi Katie, many thanks for that! I've fired off an email and will see what they come back with. If I go down to Buckingham it would give me the chance to drop in on an old friend I haven't seen for ages, so that would be good.

I'm not sure what you mean by a standalone ECU, Wally, or even if one is available for the bike. I know that the Rapid Bike Evo allows modification of the ECU in all modes, not just open loop, but BSD Performance in Peterborough maintain that they can re-write all areas of the ECU, so that makes any aftermarket add-ons irrelevant. From what Katie says, DWR can do the same, so it seems I have options in that respect.

Can I ask you how much the re-map cost, Katie?

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#6 Post by mangocrazy » Mon Dec 09, 2019 5:51 pm

Right - it's been decided. The Duke is heading down to BSD Performance near Peterborough (or PeterBogHorror as PB used to refer to it) for dyno time and a remap. They've confirmed that it's the closed loop that is the real problem and are confident that they can significantly improve the rideability (which is nice). If they can give me a bit more urge in the mid range and top end that will be a bonus, but it's the bottom end/low speed that really needs sorting.

Watch this space...

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