Switchable ignition mapping - is it all a bit of timing retard for lower octane fuel - or as I suspect - is it a lot clever these days and perhaps I'm talking about two different things?

I recall early KTM Advs had it - for lower octane as mentioned - but the latest Super Ten sport/tour D-Mode looks more sophisticated and may have nothing to do with octane, just milder throttle response and better economy.

ta

Chris

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Morocco Overland 4 (2025) • Trans Morocco Trail

I would say thats the one.

It's just a passing gimmick IMHO.


On sports bikes there was a fear of political backlash to the powerful engine outputs they were achieving with their latest models so they fitted what they called “switchable mapping” where the rider can select from a range of settings via a switch on the handle bar. Thus, you have a setting for “wet weather” so the rider would not kill himself winding on 190 bhp in second gear out of a round-about! Other settings are for “track” for obvious “political” reasons. All's they do is adjust the ignition timing but mostly the fuel injection sequence to degrade the engine performance in some way. Sometimes they can change the response of the secondary 'flies if fitted too.


To be fair, these have now evolved into semi-useful traction control and will evolve further into anti-lock braking which the EU fascists are seeking to make mandatory for all bikes and should be resisted (or better still – leave the EU ).


Some bikes are equipped with knock sensors which act as a proxy to detect the octane rating of the fuel under the conditions under which the engine is operating and can adjust the ignition timing accordingly therefore, intrinsically “switch the mapping” whilst others with EFI will adjust the injection parameters also.


A well designed EFI such as BMW's parallel twins' can run very efficiently (I haven't studied how they do this) but all bikes today are designed to meet legislative emission requirements as their “first state of tune”. Their EFI's will always attempt to achieve “stoich” or stoichiometric ratio which is the optimum for emissions (obliged by legislation) and theoretical combustion efficiency. However, this is seldom the optimum state of tune for either maximum power or maximum fuel economy and a good EFI will have sufficient sensors and software to enable both – except for the emissions requirements getting in the way all the time!


The biggest obstacle to the happy medium is the OEM's choosing to fit (for cost reasons) narrow-band lambda sensors in the exhaust stream. These are only capable of detecting rich or lean and act more like a switch than a sensor. Wide-band sensors are available which can enable a far more subtle EFI response and will produce perfect fuelling under all conditions, can run your engine to the extremes of lean (and therefore fuel economy) as well as “best power” and response.


To get to this happy sate you will have to junk your standard ECU and learn about after market ECU's (cheaper too than OEM's). You can tune your engine how you like, tune each cylinder individually, tune for a different map for each gear, tune on the fly from your mobile phone if you wish so there really is no requirement whatsoever for “switchable mapping”.


MegaSquirt is the way to go; it's all open source and the latest MicroSquit is designed especially for bikes and other small engines and I'm hoping to find one under my Christmas tree in a few weeks



Incidentally, the hated EU is proposing legislation which will make it illegal for all but “official” technicians to open up or otherwise modify your engine and also to compel official technicians (i.e. your “official” dealer) to report you to the authorities for prosecution for doing so under pain of two years imprisonment. Luckily the hated EU is about to implode and leave us all the alone!!!

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Are there any other bikes then BMW that use a knock sensor? Do you know if it alters the mixture (on the BMWs)? As far as I know they can use Super on the emission-tests so it should be possible to pass the test on Super and run fatter on low-octane.
Can you wire a knock-sensor to MegaSquirt and use it for mapping?


Back to the switch..... There is a switch on the (old) BMW G450X Enduro. I'm not sure if it helps for low-octane but it helps a lot where there is low traction.

The BMW F800 (actually not a BMW but a ROTAX engine) doesn't use a knock sensor. There are more knowledgeable peeps on here about that bike them me but I seem to remember reading that BMW dealers will download a new map for lower octane fuels if you ask them nicely. That engine probably runs high compression and has a good combustion chamber design. Also it's a light(ish) weight bike, well geared hence the good fuel economy. The GS has knock sensors though.


Honda's super sports bikes have had knock sensors on them for a while now ( NGK SPARK PLUG CO., LTD. | Others ) but to me they seem very useful on a ADV bike where you might encounter the different conditions likely to cause knock, factors like unknown fuel type, air temperature extremes, coolant temperature extremes, air/fuel mix, air density, etc, etc. and you have tuned the engine to the extremes of lean to get extra range out of it. Best of all is to have a simple motor that will be unlikely to knock in the first place 'cos it's knackering to the engine!


Third party sensors can be wired to Megasquirts and you adjust the software to suit



but to counter knock the ECU will retard the ignition not enrich the mixture.

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Thanks!
Megasquirts looks a bit experimental. Is it suited for Adv-bikes? Do they make a kit for bikes?

You're correct, by definition they are experimental. It's similar to Linux in that no charge is made for the software, it's all open source and you are encouraged to contribute results & improvements back for the good of everyone. If you are good with a soldering iron you can even assemble your own ECU from plans and a bag of bits you can buy off ebay and only build in the features you desire. For that reason there is no specific ECU for any bike or car, you design it for any engine you have in mind. They have been used on everything from chain saws to 32 cylinder aero engines! Here's someone who's squirted a monkey bike engine : Monkey Pit bike engine Microsquirt ECU EFI fuel ignition injection - YouTube

The virtue of squirting is that it forces you to understand deeply every aspect of your engine - it's addictive!

It's definitely suited to ADV bikes but I would suggest as a replacement for the OEM ECU. i.e. utilise the existing sensors and injectors and use the software to tune your bike how you wish (with the addition of a wideband lambda sensor that is).

The latest microsquirt V3.0 is about the size of a credit card and you can buy them ready built with the features you specify.



and you can learn more from the site here : http://www.useasydocs.com/quickstart.htm

free linux tuning software: http://megatunix.sourceforge.net/

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Thanks, this looks far better then the old big boxes I found when I search for MicroSquirt.
I will read through it and hopefully use it for a later project. Soldering and programming is no problem.

I'm sure it can be addictive