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--- tecnica:motori:honda_ntv650_troubleshooting [2024/09/09 11:44] – [Ignition coils and pulse generator] niccolo
+++ tecnica:motori:honda_ntv650_troubleshooting [2024/11/01 15:54] (current) – [Mid RPM sputtering] niccolo
@@ Line 1: / Line 1: @@
-====== Honda NTV650 Revere Troubleshooting ======
+====== Honda NTV650 Revere - Troubleshooting ======
-===== Spark unit =====
+===== Popping (backfire) when shifting down on engine braking =====
-^ Green/White  | Ground  | It connects to the ground when it is OK to run the engine. Goes to the clutch switch, the side stand switch and the neutral switch diode.  |
+The problem started to appear gradually, increasing over time. The popping became very annoying especially on steep descents when using engine braking in low gears. In general this problem is caused by a lean air/fuel mixture (poor in gasoline). The wrong ratio causes some misfires, the unburned gasoline then explodes in the exhaust due to the high temperature.
-^ Yellow/Blue  |  | Goes to the rear ignition coil. Gets the +12V battery voltage when the engine stop switch is on the RUN position and the ignition switch is ON.  |
-^ Black/White  | +12V  | It gets the +12V through fuse #6 when the engine stop switch is on the RUN position and the ignition switch is ON. Goes to the ignition coils and to the engine stop switch.  |
-^ Blue/Yellow  |  | Goes to the front ignition coil. Gets the +12V battery voltage when the engine stop switch is on the RUN position and the ignition switch is ON.  |
-^ Green  | Ground  | Always connected to the ground.   |
-^ Light green/Red  | Ground  | It connects to the ground when the gear is in neutral position. Goes to the neutral switch.  |
+I solved it with a thorough cleaning of the carburetors, paying particular attention to the air cut-off valve circuit and the idle jets; see this article: **[[honda_ntv650_carburetor]]**.
-===== Starter relay switch =====
-^ Green/Red  | Ground  | It gets the ground when is it OK to start the engine. Goes to the clutch switch, to the side stand switch and to the neutral switch diode.  |
+===== Mid RPM sputtering =====
-^ Yellow/Red  | +12V  | It gets the +12V through fuse #6 when the start button is pressed. Goes to the starter switch.  |
-===== Fuel pump relay and fuel pump =====
+After a **long period of non-use** (16 years), I restarted an NTV650. I had already cleaned the carburetor from the **sludge that had formed following the evaporation of the petrol**.
-^ Blue/Black   | +12V  | It gets the +12V when the relay is switched-on (the engine is running). Goes from the fuel cut relay to the fuel pump.   |
+The bike starts easily and **holds the minimum speed well**, but when you increase the gas, **around 3000 - 4000 rpm, it begins to splutter** noticeably. After a few minutes of operation it seems that the front cylinder does not work because it is practically cold, unlike the rear which has reached the temperature. After checking the ignition coil by measuring the resistance of the primary and secondary windings and verifying that there was a spark at the spark plug, I decided that I had to disassemble the carburetors again.
-^ Black        | +12V  | It gets the +12V when the ignition switch is ON. It goes to the fuse #6.  |
-^ Blue/Yellow  |  | It gets the signal from the ignition coils to switch the relay ON. It goes to the spark unit.  |
-===== Ignition coils and pulse generator =====
+It turned out that the idle circuit had been cleaned correctly, in fact the bike worked perfectly at idle. But **the main jet duct still contained some dirt**: opening the throttle the air/fuel mix were **too lean**, to the point that the engine ran on only one cylinder. **The uncobusted petrol sometimes was detonating**, thus the sputtering.
+===== Web resources =====
-Measure the resistance of the primary and secondary ignition coils, then the resistance of the pulse generator coils. Reference values are for 20°C/68°F.
+  * **[[https://www.thumpertalk.com/forums/topic/1477581-mid-rpm-sputtering/|Mid RPM sputtering]]**
+  * **[[https://www.thumpertalk.com/forums/topic/964557-engine-stutters-while-trying-to-hold-a-constant-speed/|Engine stutters while trying to hold a constant speed]]**
-=== Primary coil resistance ===
-  * **Blue/Yellow** - **Black/White** (rear): 2.2 - 2.6 Ω (ohm)
-  * **Yellow/Blue** - **Black/White** (front): 2.2 - 2.6 Ω (ohm)
-=== Secondary coil resistance ===
-  * Between **spark plug caps**: 30 - 36 kΩ (kohm)
-  * Between **terminals** (spark plug wires removed): 20 - 25 kΩ (kohm)
-=== Pulse generator resistance ===
-  * **White/Yellow** - **Yellow** (front): 450 - 550 Ω (ohm)
-  * **White/Blue** - **Blue** (rear): 450 - 550 Ω (ohm)