@ Selin
Sorry for the late reply to your question.
It is true that the Acra - mp for the 690 gives more fuel to the engine. But it changes not only the fuel curve. It looks like as it also advances the ignition advance to squeeze out more power.
When I set up a motorcycle on the dyno the first step is to identify which air/fuel ration makes the best performance for an engine. This is a try-and-error job.
Lambda 0,9 - meaning an excess of 10% fuel compared to the stoichiometric 14,7 at Lambda = 1 - is always a good starting point for this procedure. But some engines prefer a leaner mixture to crank out the best, the engineer has packed into, running at an air/fuel - ratio of up to Lambda 0,95. Other engines are asking for more fuel and "like" an air/fuel - ratio of Lambda 0,85 for example. When Lambda goes down to 0,8 meaning an excess of 20% fuel for the mixture, most engines are lacking performance.
The KTM 690 engines run - no matter if the stock map or an Acra is loaded to the ECU - with Lambda 0,82. This is pretty rich, so rich, that most Japanese bikes would refuse to burn such a sea of fuel. At Lambda 0,9 the engine output does not drop significantly, but the engine starts to show symptoms of running lean on the dyno: the power out put, the graph displayed, is not smooth anymore but rough and erratic.
I explained this in such detail to make clear that the 690 - engine is different. You must not apply the a/f - readings to this engine, you are used to and which work for most common bikes on the dyno: The KTM has a large piston of 102mm bore and a compression ration exceeding 12:1. Therefore it likes - obviously - an extra spray of fuel to calm and cool things down. And the Acra map with some more ignition advance needs even more fuel.
To come back to your question: The Acra - map for the 690 may cover its demand for fuel by the better flowing pipe pretty nicely. But it is not designed by KTM for the better air flow created by the air box lid removed. This modification puts a ton of new and additional torque on the crank from the very bottom up to 5000 RpM. At the very end of the rev range the engine is limited by its cam timing to transmute this rush of air into power here. Therefore the peak power and its demand for fuel remains rather unchanged.
But up to 5 grand the removing of the air box lid releases up to 10-15% more torque. This new engine power needs additional fuel to keep the a/f - ratio of the 690 within its individual and desired limit of 0,82. This is the job, the "Kastl" is doing. Behind 5000 up to the very end of the range it changes the fuel curve just slightly, because there is no need for it. But within the area, the new torque occurs, it makes the ignition pulses 10-15% longer to spray the fuel into the engine port, the new air is waiting for.
When checking a 690 with flowed air box side by side with and without "Kastl" on the dyno, the peak power remains rather unchanged. Peak power is made by the engine within that rev range, where the unleashed air flow makes no huge difference to performance. But within said range up to 5000of the new and additional torque, you will get a smoother power delivery and some 5% more torque, transforming into 1-2 additional HP here.
So the difference is clearly visible on the dyno graphs, although not so impressive as you may aspect. The bigger part of the new power and torque is created by the additional air flow.
The new fuel map by the "Kastl" brings the a/f -ratio back within the genuine safety limits. It may also enhance thereby engine response compared to an operation without "Kastl".
You have to decide if this are advantages worthwhile.
Highscore
