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Discussion Starter · #3 ·
Thank you for your prompt reply! I guess it should then be this guy
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I guess I'll have to remove the main seat, at least, in order to access it. Again, if anyone already did it, please share your advices. I thank you in advance.
The reason I'm doing this "research" is because recently my 390 is behaving oddly while warming up (before reaching the 7/8 bars of temp in the display) with the engine doing some hiccups/misfiring during gentle accelerations. If I push it a bit harder I'd say I cant feel this behavior, and after reaching the working temperature it performs/behaves as expected, no hiccups, just plain and smooth.
Spark plug (NGK Iridium) is new (less than 5k km), air filter, the same, so I'm excluding them as potential culprits. Fuel pressure, stator, ignition coil, related issues should (?) keep popping up even after functioning temperature is achieved, I guess.
Valve clearance is to be checked in the coming weeks (less than 1k km) to the next service, but I'd say it is not related to this as well.. not completely sure though....

For now, I'd like to reach that temp sensor, hopefully it has something to be cleaned...
 

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You'll have to remove the seats and the petrol tank as well to access the MAP sensor. Make sure to clean around the map sensor properly before you remove it, you don't want any dirt or debris fall into the throttle body through the MAP hole when you remove it.

I've removed my throttle body and cleaned it, including the MAP sensor here : JHoe's Duke 390 revival!

i think you better go the whole way and clean the throttle body as well. I feel the Idle steper motor might have an issue in your case.
 

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Discussion Starter · #5 · (Edited)
Ok, got it! Thanks.
One question regarding the stepper. If I see it right (and I may not...) it's function is to manage idling, once we turn the gas on it has no influence on engine regime/behavior. If this assumption is correct and since the hiccups occur around 4 or 5k rpm, I'd say the stepper wouldn't interfere (?!)
Once you are definitely several steps ahead on this matter... I'd like to know what you think.

Thank you
 

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One question regarding the stepper. If I see it right (and I may not...) it's function is to manage idling, once we turn the gas on it has no influence on engine regime/behavior. If this assumption is correct and since the hiccups occur around 4 or 5k rpm, I'd say the stepper wouldn't interfere (?!)
Correct, the stepper is relevant only when the throttle is fully closed
 

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Discussion Starter · #10 ·
I'll investigate that... Nevertheless, I suspect it won't be as effective as disassembling and cleaning it while apart. On the other hand it might be a quite easier approach...
 

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Discussion Starter · #11 · (Edited)
Deep cleaning - check

It had a considerable amount of smoke/charcoal/dust, ... spread all over. MAP and stepper were, at least in a visible perception way, the most affected.
Some CRC MAF cleaner, a soft small brush and a few minutes later all parts were almost clean as in the first day
First run after all being back to its place suggests the Duke runs now as smooth as it is supposed to. No more perceptible hiccups around 4.5k and 5.5k rpm!

Thank you all for your help and contributions

Merry Christmas
 
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