[{"content":" TADA !! After long hours of debug i finally reached to write swing keihin ECU.\nI let you doing the tour of the software. Checksum is verified before writing and you will have a save proposal.\nHonda Swing Flasher\nTo flash ecu you will have 2 ways :\nConnection on diagnostic plug, but be carefull you will need a strong battery charger during the actions, Lots of equipment are runing when butterfly box is not joinable.\nConnection on table with pinout provided inside software.\nYou will find nice stuff including map editor. All of that for FREE!\nENJOY!\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-05-11-here-we-go/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"tada-\"\u003eTADA !!\u003c/h2\u003e\n\u003cp\u003eAfter long hours of debug i finally reached to write swing keihin ECU.\u003c/p\u003e\n\u003cp\u003eI let you doing the tour of the software. Checksum is verified before writing and you will have a save proposal.\u003c/p\u003e\n\u003cp\u003e\u003ca href=\"Honda_Swing_125_Flasher.zip\"\u003eHonda Swing Flasher\u003c/a\u003e\u003c/p\u003e\n\u003cp\u003eTo flash ecu you will have 2 ways :\u003c/p\u003e\n\u003cp\u003eConnection on diagnostic plug, but be carefull you will need a strong battery charger during the actions, Lots of equipment are runing when butterfly box is not joinable.\u003c/p\u003e","title":"2026 05 11 Here We Go"},{"content":" Bench preparations Reading/Writing ECU on the scooter directly is not nice, the scooter is keeping some equipments ON and is draining the battery. And i will have to manage the writing part of my software on the KO Parts i will grab.\nSo i decided to create a cable to connect directly to the ECU.\nFor that i used some recycled parts :\n-Galletto 1260 4 pins adapter : -a 12Vdc PSU\n-1 on off switch\n-a designed box printed in petg: Download the stl file\nThen i used this pinout to solder the cable (Only GND, Kline and Lline): This is the ecu pinout : To make the wires small connectors i used Parkside kit : The cable done : The ON/OFF switch is useful because the ecu is giving access in reading or writing mode just during some seconds after power on cycle. When it is switching on we can hear some mechanical parts inside.\nI will complete with pictures at first tries.\nLinks to buy parts (for examples) Galletto on Amazon.\nParkside toolset Lidl.fr\nKKL Cable to read/write on Amazon.\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-05-03-bench-preparations/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"bench-preparations\"\u003eBench preparations\u003c/h2\u003e\n\u003cp\u003eReading/Writing ECU on the scooter directly is not nice, the scooter is keeping some equipments ON and is draining the battery.\nAnd i will have to manage the writing part of my software on the KO Parts i will grab.\u003c/p\u003e\n\u003cp\u003eSo i decided to create a cable to connect directly to the ECU.\u003c/p\u003e\n\u003cp\u003eFor that i used some recycled parts :\u003c/p\u003e","title":"2026 05 03 Bench Preparations"},{"content":" ECU MAP Studies Before receiving another CDI 16400-KRJ-792 i decided to run a bit the swing on the road.\nAnd i saw that it was ok upto about 7000/7500 rpm about speed, but after that it was long to achieve 100km/h.\nI was suspecting a limitation to A1 (11kw) reglementation, ok that can be from variator or clutch but as i felt it wasn\u0026rsquo;t. I am clearly limited.\nTo remind, this is my original file : H8/3687G File\nI decided to put it in Claude (Anthropic) analyse with some elements and he found some probable limiters exactly into this zone.\nFirst of all, the step between about 6500 and 10000 rpm is not detailed in the maps, no modifications of injection. We are injecting same between these 2 values\u0026hellip;.. seems not optimal.\nAnd Second point he found that into CPU program a MOV was done :\nAddress Value RPM Role 0x5A8C 0x0F5D 7627 Primary rev limiter (CMP) 0x6AD4 0x0F5D 7627 Primary rev limiter (MOV) 0x4D18 0x0E39 8239 Secondary rev limiter 0x69D2 0x0E39 8239 Secondary rev limiter 0x60B6 0x0B61 10298 Safety rev limiter — KEEP 0x60C0 0x09F5 11769 Hard cut-off — KEEP And this is exactly where i am blocked when i drive it. Like if it was at maximum. But dashboard showing the redzone from 10k to 12k\u0026hellip;\nI know you will say that dashboard can show what we want but not always how they run. But inside code we can see same rev limiters as the redzone : | 0x60B6 | 0x0B61 | 10298 | Safety rev limiter — KEEP | | 0x60C0 | 0x09F5 | 11769 | Hard cut-off — KEEP |\nMy first check will be on the first limiter, to put it at 9k. And if it goes better i will have to modify injection map to add the missing rows between 6k and 10k\u0026hellip;. to avoid runing without enough gazoline.\nTo be continued\u0026hellip;\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-05-03-ecu-map-studies/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"ecu-map-studies\"\u003eECU MAP Studies\u003c/h2\u003e\n\u003cp\u003eBefore receiving another CDI 16400-KRJ-792 i decided to run a bit the swing on the road.\u003c/p\u003e\n\u003cp\u003eAnd i saw that it was ok upto about 7000/7500 rpm about speed, but after that it was long to achieve 100km/h.\u003c/p\u003e\n\u003cp\u003eI was suspecting a limitation to A1 (11kw) reglementation, ok that can be from variator or clutch but as i felt it wasn\u0026rsquo;t.\nI am clearly limited.\u003c/p\u003e","title":"2026 05 03 ECU MAP Studies"},{"content":" Phone fixture model As this scooter is my new lovely travel device, i wanted to fix my phone on it.mostly for GPS. After some search i saw that it was difficult to find something correct for my budget. Then i decided to design one\u0026hellip;. i focused on creating a 17mm ball then you will be able to add what you want on it.\nStl file\nAnd then you can put this kind of phone holder : Get it on Amazon.\nThis was just while i am waiting for new ecus\u0026hellip;.\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-04-30-extra/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"phone-fixture-model\"\u003ePhone fixture model\u003c/h2\u003e\n\u003cp\u003eAs this scooter is my new lovely travel device, i wanted to fix my phone on it.mostly for GPS.\nAfter some search i saw that it was difficult to find something correct for my budget.\nThen  i decided to design one\u0026hellip;.\ni focused on creating a 17mm ball then you will be able to add what you want on it.\u003c/p\u003e","title":"2026 04 30 Extra"},{"content":" Whats inside the files? The goal now is identifying the maps and data from Renesas chip and 93C66. Winols is a kind of Rolls to manage and edit files. I used it in the past and had to re open it. I won\u0026rsquo;t speak about it here and won\u0026rsquo;t provide any link. Just to say that you can download a DEMO version for free and see what\u0026rsquo;s inside the ECU. I am not a pro of tuning, and not familiar with petrol engines. Most familiar with TDI lol.\nRenesas H8/3687 Potential maps list : Some of them : What about IAT sensor? The IAT sensor is located on the butterfly body side. It is a kind of dark pipe soldered directly on the PCB :\nPins : The goal is looking where it is connected on the H8 chip, there are multiple ADC channels on B port:\nAN0 (ADDRA) → pin 80 (PB0) AN1 (ADDRB) → pin 79 (PB1) AN2 (ADDRC) → pin 78 (PB2) AN3 (ADDRD) → pin 77 (PB3) AN4 → pin 76 (PB4) AN5 → pin 75 (PB5) AN6 → pin 74 (PB6) AN7 → pin 73 (PB7)\nActually my only one CDI (ECU) is used inside the scooter, I will continue this part once i receive another one.\nThe goal is, to urgently help owners, beeing able to flash the scooter from the diagnostic plug and correcting that.\nWe have multiple possibilities :\n-\u0026gt; disabling DTC -\u0026gt; bad, value will be bad and will generate wrong calculation -\u0026gt; soldering a resistor -\u0026gt; bad for same reason \u0026hellip;\nMy idea is fixing the IAT value to 17° (for exemple) and this will disable DTC. In my region it is the mean temperature of a year.\nAfter some estimations, that will affect the injection at about -3%/+3% which could be really correct to continue using our Swing to go working.\nCompared buying a brand new 1640-krj-793 version at about 600 euros plus handwork fees, flashing CPU could spend about the price of the cables so about 30 euros\u0026hellip;.\nHow? To change this part, we won\u0026rsquo;t go inside map part of the H8 file. We will have to find inside H8 program.\nTo identify where in the code we need to know where the sensor is connected. We are back to the wait of the new CDI.\nStep 1 — Pin → ADC channel → register The H8/3687 ADC is a single 10-bit converter multiplexed across 8 inputs (AN0…AN7). Each AN pin maps to one of four data registers (ADDRA…ADDRD) plus the channel-select bits inside ADCSR. Once i have the pin number, I know exactly which ADDR register holds the IAT result.\nStep 2 — Filter the 77 ADC accesses I already have a list of every byte in the firmware that reads MOV.B @0xFFAx, R. I keep only the ones that target the IAT register identified in step 1. The \u0026ldquo;77 hits\u0026rdquo; usually drops to 5–15 candidate sites.\nStep 3 — Distinguish init code from runtime read A few of those hits are setup code (writing to ADCSR to start a conversion). I drop those. What remains are the post-conversion reads of the IAT result. Typically only 2–4 sites survive — and one of them appears in a tight loop or an interrupt handler that runs every few ms. That\u0026rsquo;s the periodic IAT acquisition routine.\nStep 4 — Confirm by following the data flow After the MOV.B @0xFFA, R instruction, the value is normally:\nstored into a RAM cell (e.g. MOV.B R, @0xFE??), then compared against two limits via CMP.W #imm:16, R followed by a conditional branch that triggers a DTC-set helper (DTC 9-1 / 9-2), and used as an index into a small NTC linearization LUT in the calibration zone (the 18-pt curves we already mapped at 0xA05C / 0xA06E / 0xA080 are strong candidates). Finding two consecutive CMP.W immediates with one low value (~0x20–0x60) and one high (~0x300–0x3D0) right after our targeted ADC read is the smoking gun: it\u0026rsquo;s the IAT range check that produces the DTC.\nStep 5 — Write the patch minimal-invasive at that site:\nConstant injection — Replace the MOV.B @0xFFA, R (4 bytes) with MOV.B #0x80, RL (2 bytes) followed by a NOP NOP to keep alignment. The CPU now always loads the same fixed ADC value (~512 of 1023 ≈ 17 °C), the LUT outputs a normal temperature, the DTC threshold check passes, and the fueling correction gets a sane constant.\nThis is the plan to patch IAT sensor.\nThat\u0026rsquo;s the full pipeline: pin → register → 5–15 candidates → 2–4 finalists → 1 patch site → 2–4 byte modification.\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-04-30-files-analyse/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"whats-inside-the-files\"\u003eWhats inside the files?\u003c/h2\u003e\n\u003cp\u003eThe goal now is identifying the maps and data from Renesas chip and 93C66.\nWinols is a  kind of Rolls to manage and edit files.\nI used it in the past and had to re open it.\nI won\u0026rsquo;t speak about it here and won\u0026rsquo;t provide any link.\nJust to say that you can download a DEMO version for free and see what\u0026rsquo;s inside the ECU.\nI am not a pro of tuning, and not familiar with petrol engines.\nMost familiar with TDI lol.\u003c/p\u003e","title":"2026 04 30 Files Analyse"},{"content":" Diagnose Plug of the Silver Wing 125 The diagnostic Connector is near the battery under the seat, you have to unmount 1 cover to access it. The connector is coverred by a red cap to remove. it is a 4 Wires version. I will post picts asap about it.\nHowto connect? You need 2 things :\nOBD 4 pin adapter Get it on Amazon.\nAnd 409.1 KKL cable ( FT232 and tranceiver ) Get it on Amazon.\nPlug them all together and to the scooter and that\u0026rsquo;s it.\nProtocols The scooter can communicate in K-Line and in J2534 (normally, not tested yet).\nCoding a program I decided to code a program to connect to the scooter and investigate into the ECU. The goal is to understand how it works and maybe find some bugs or improvements. And one of my goals is finding a solution to IAT issue.\nI choosed Python for the easy part of it. And could be easier released as opened sources.\nThe reading process of the H8 takes about 15/20 minutes\u0026hellip;. I used a battery charger to keep 12v tension because the scooter is switching on : lights gasoline pump fan \u0026hellip;.\nECU H8/3687G and 93C66 reading As in car tuning, the CDI (ECU) containing 2 memories, 1 inside the Renesas H8/3687G and one inside a tiny 93C66 eeprom.\nGenerally, main CPU containing CDI program and injection tables, and eeprom containing immo, options, odometer \u0026hellip;. Interested about whole system i wanted to read each.\nSo after some debug i achieved to read both of them. I will detail the process in a future post. For now, let\u0026rsquo;s focus on what i read.\nOriginal Files You will find below both files : H8/3687G File 93C66 File\nTo validate the read, i read both files 2 times and compared readings and each read was same.\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-04-29-diag-plug-and-ecu-reading/","summary":"\u003c!-- Write your post here in Markdown --\u003e\n\u003ch2 id=\"diagnose-plug-of-the-silver-wing-125\"\u003eDiagnose Plug of the Silver Wing 125\u003c/h2\u003e\n\u003cp\u003eThe diagnostic Connector is near the battery under the seat, you have to unmount 1 cover to access it. The connector is coverred by a red cap to remove. it is a 4 Wires version.\nI will post picts asap about it.\u003c/p\u003e\n\u003ch2 id=\"howto-connect\"\u003eHowto connect?\u003c/h2\u003e\n\u003cp\u003eYou need 2 things :\u003c/p\u003e\n\u003cp\u003eOBD 4 pin adapter\n\u003cimg alt=\"Caption\" loading=\"lazy\" src=\"/projects/honda-silverwing-125/2026-04-29-diag-plug-and-ecu-reading/OBDAdapter.png\"\u003e\nGet it \u003ca href=\"https://www.amazon.fr/dp/B0CYST4BP7/?tag=maxofun-21\" rel=\"nofollow sponsored noopener\" target=\"_blank\"\u003eon Amazon\u003c/a\u003e.\u003c/p\u003e","title":"2026 04 29 Diag Plug and ECU Reading"},{"content":"Context Arf honnestly i expect that i could help people with some tricks. Actually these scooters are sold for pieces in mass because of 1 major issue the butterfly body, which is containing CDI and injection management. This part is suffering of a lack of studies according heat dissipation, humidity\u0026hellip;. And some solderings inside are leaving their fonctionnalities.\nLet\u0026rsquo;s introduce you to the Keihin 16400-KRJ-792 : This device grab multiple information and acting in fact of them.\nLet\u0026rsquo;s opening it Harder than expected, once you have unscrewed the 4 torx the task is not the same. The box is sealed with a flexible sealant :\nAnd clearly i had to heat the cover to unglue it\u0026hellip; this resulted to that : Then i thought from there that i should draw something :\nDownload the stl file\nStill in debug\u0026hellip;\nCleaning Time OK to remove the sealant, nails and a bit of acetone with an old toothbrush did the trick. Now it\u0026rsquo;s ok : PS : This pict is after resoldering\u0026hellip; excuse me for bad aspect of them i did that late in the night and for testing purposes\u0026hellip; and honnestly i was not expecting a nice issue.\nThe most important pins are : Soldering station, flux and soldering paste or leaded solder are usefull. and toothbrush again\u0026hellip;\nTesting Time With a debug cover to avoid troubles : Printed in PLA just to have a small try. another one in ASA-CF is ready for longer tests : First start was ok and seems more reactive at throtle. Waiting for the road test.\nto be continued..\nEDIT 30/04/2026 - About 8km without any FI light. lets see if it stays like that.\nTo support me Thank you ","permalink":"https://maxofun.fr/projects/honda-silverwing-125/2026-04-26-ecu-repair-first/","summary":"What\u0026rsquo;s inside","title":"ECU Opening Time"}]