[Mirius]

Piggyback ECU's can't overcome phisical lack of fuel. Engine modifications on intake and exhaust will require higher flow injector or higher rated fuel pressure regulator to avoid lean conditions at WOT or open loop... Higher rated FPR can be used with the stock ECU also.

Plug in piggy back ECU, Why one?

Regards.

If you speak to the suppliers who spent the time when the RC390 racing scene was a thing (does it still exist?) such as grey area KTM then they will tell you the stock injection has enough headroom for the modest airflow changes that most riders make. Naturally a point comes when one is needed but is not always a factor in deciding a piggyback.

As for why one, well this is my opinion but a locked ECU on the gen 2 means not so much point putting it on a dyno for lots of runs with that slow not very self learning process and emissions controls built into the stock map.

 

[Alf]

Although you have some valued points I wonder why various piggyback produce their dyno maps/charts showing some (marginal) power and/or torque increases that can be reproduced by anyone with a dyno?
Obviously, there will be maps that are shown in the utmost favourable conditions but nevertheless, they generate an increase.
Now I am intrigued by your remark(s) on increasing the line pressure to the injector and/or a 'larger' injector but would the ECU not reduce the amount of fuel being injected (shortening the injection time) when the O2 sensor detects a too rich AFR?
I am living in a country where basically nothing motorcycle wise is available so I always try to make sense of it all before I start ordering stuff from other places that for me take at least a month to arrive and obviously is more expensive to get in the Lao PDR.
An interesting discussion, I think.

Yes, it's not about demonize piggyback ECU's. They can be useful when the degree of engine modifications make the stock ECU unable to manage the new configuration. But as I stated, they have also serious limitations.

But that is the point: piggyback ECU'S are expensive, not available in all markets (after sales service) and not always worth the investment. To compensate for a moderate (naturally aspirated) increase on air flow (airbox lid, decat pipe) you don't need a piggyback ECU: a higher rate fuel pressure regulator may be enough.

A FPR is nothing but a membrane with a spring. If your market have restrictions on imported goods (for example: abusive import taxes, ridiculous delays on customs clearance, communism...), you can increase the pressure rate of your stock FPR by compressing (deforming) one or two millimeters the top of the spring housing. A socket, a vise and prudence should be enough to achieve this. Free commerce and democracy are always a better starting point for engine modifications. 😁

You have to distinguish between open loop and closed loop operation on your KTM engine (O2 narrowband lambda sensor present). In closed loop operation (low RPM, cruising at steady RPM) the ECU will read lambda signal and correct the pulse duration opening the injector to match factory defined AFR map. In open loop operation (Idle, accel transient, WOT) O2 sensor feedback is not used: The ECU don't know you are using more pressure on your fuel line and will use the same injector opening pulse duration defined by factory for a 3.0 BAR FPR for that load, but with a, let's say, 3.5 BAR FPR . This is why you can use increased pressure rate FPR and stock ECU to compensate moderate increase on engine's air flow.

Closed loop + higher rated FPR for fuel efficiency, better driveability and low emissions, open loop + higher rated FPR for power. The best of two worlds in one reliable and perfectly factory tuned stock ECU VS. "let's swap" some ignition maps in the piggyback 🐖, and see if engine doesn't self destruct inmediately knock knock knocking on heaven's door 💸💸💸.

Regards.

 

[Artem]

Not to steal your thread or anything but I have a question for the masses running RBE. I know you can make adjustments, what realistic mods could you run using this? Would it be safe to run any of these combinations?


1. K&N Filter stock everything else
2. K&N Filter with holes drilled into the air box (3 nickel size holes)
3. K&N Filter with open air box (MMNTHBX)
4. K&N Filter with modified air box and exhaust.
5. K&N Filter with Exhaust


Just testing the waters to see what is in the realm of realistic results.

Not to steal your thread or anything but I have a question for the masses running RBE. I know you can make adjustments, what realistic mods could you run using this? Would it be safe to run any of these combinations?


1. K&N Filter stock everything else
2. K&N Filter with holes drilled into the air box (3 nickel size holes)
3. K&N Filter with open air box (MMNTHBX)
4. K&N Filter with modified air box and exhaust.
5. K&N Filter with Exhaust


Just testing the waters to see what is in the realm of realistic results.

Could someone reply to this question? Would it be OK to add K&N filter, possibly with a modified air box while using one of the two piggyback original author has suggested? Everything else is stock.

 

[KTMasean]

Sounds interesting,
Do you have any graphs/dyno runs other proof of this actually working?

Yes, it's not about demonize piggyback ECU's. They can be useful when the degree of engine modifications make the stock ECU unable to manage the new configuration. But as I stated, they have also serious limitations.

But that is the point: piggyback ECU'S are expensive, not available in all markets (after sales service) and not always worth the investment. To compensate for a moderate (naturally aspirated) increase on air flow (airbox lid, decat pipe) you don't need a piggyback ECU: a higher rate fuel pressure regulator may be enough.

A FPR is nothing but a membrane with a spring. If your market have restrictions on imported goods (for example: abusive import taxes, ridiculous delays on customs clearance, communism...), you can increase the pressure rate of your stock FPR by compressing (deforming) one or two millimeters the top of the spring housing. A socket, a vise and prudence should be enough to achieve this. Free commerce and democracy are always a better starting point for engine modifications. 😁

You have to distinguish between open loop and closed loop operation on your KTM engine (O2 narrowband lambda sensor present). In closed loop operation (low RPM, cruising at steady RPM) the ECU will read lambda signal and correct the pulse duration opening the injector to match factory defined AFR map. In open loop operation (Idle, accel transient, WOT) O2 sensor feedback is not used: The ECU don't know you are using more pressure on your fuel line and will use the same injector opening pulse duration defined by factory for a 3.0 BAR FPR for that load, but with a, let's say, 3.5 BAR FPR . This is why you can use increased pressure rate FPR and stock ECU to compensate moderate increase on engine's air flow.

Closed loop + higher rated FPR for fuel efficiency, better driveability and low emissions, open loop + higher rated FPR for power. The best of two worlds in one reliable and perfectly factory tuned stock ECU VS. "let's swap" some ignition maps in the piggyback 🐖, and see if engine doesn't self destruct inmediately knock knock knocking on heaven's door 💸💸💸.

Regards.

 

[KTMasean]

Artem,
Both the RBEasy and the Booster Plug are "dumb" piggybacks in that these will not recognise any modifications on the airflow system (in- or out).
To be on the safe side you would be looking at more advanced units such as a Rapid Bike EVO, PowerTRONIC etc.
I understand that there is some adjustability on an RBEasy but I have no experience as to how far you are able to modify until it goes potentially wrong.

Could someone reply to this question? Would it be OK to add K&N filter, possibly with a modified air box while using one of the two piggyback original author has suggested? Everything else is stock.

Could someone reply to this question? Would it be OK to add K&N filter, possibly with a modified air box while using one of the two piggyback original author has suggested? Everything else is stock.