Differences

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--- tecnica:motori:honda_ntv650_carburetor [2024/09/23 12:15] – [Hoses position] niccolo
+++ tecnica:motori:honda_ntv650_carburetor [2024/10/29 10:14] (current) – [Replacing the diaphragms at 100.000 and 200.000 km] niccolo
@@ Line 1: / Line 1: @@
 ====== Honda NTV650 Revere - Carburetor ======
-The Honda NTV650 Revere mounts two **Keihin** vacuum piston carburetors. Each carburetor has also an **air cut-off valve** driven by a small membrane.
+The Honda NTV650 Revere mounts two **Keihin** vacuum piston carburetors. When servicing the carburetors, it must be kept in mind that in addition to the **vacuum piston diaphragm**, there is also a small diaphragm that operates the **air cut-off valve**.
 Here it is my experience in **replacing the diaphragms** and some information on the little-known **air cut-off valve**.
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 As soon as they were mounted, the result seemed good: the precision and sensitivity of the throttle was significantly improved compared to the old cracked membranes. In a few months I will check the actual seal of the membrane and especially of the glue. The one supplied reports among its characteristics a maximum operating temperature of 80 °C. Probably the Loctite 454 has better characteristics.
-In the following picture you can see the mounting position of the diaphragm, seen from below:
+In the following picture you can see the mounting position of the diaphragm. You can see the angle with the vertical axis measuerd on the top cover and a view of the piston from below:
-{{.:honda_ntv650:diaphragm-position.jpg?200|Diaphragm original position}}
+{{.:honda_ntv650:carburetor-diaphragm-alignment.png?240|Diaphragm alignment}}
+{{.:honda_ntv650:diaphragm-position.jpg?240|Diaphragm original position}}
 ===== Jets and pilot screw =====
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 The **factory settings** are likely to be for a **very lean mixture** at idle, which is also why the cut-off valve is needed. This setup is required to meet stringent pollution regulations. It may be that the best idle performance is achieved with a richer mixture (pilot screw turned out more than two turns). A richer idle also reduces the possibility of afterburn (exhaust popping) when the throttle is released.
-===== Fuel and breather pipes position =====
+===== Fuel and breather pipes placement =====
-In the following photos you can see how the fuel line and the breather tube are positioned around the carburetors. This is how I found them in my 1991 Revere, but I found other models having the breather tube going to the right side, in a mirror-like way.
+In the following photos you can see how the fuel line and the breather tube are positioned around the carburetors (the lower end of the breather pipe should be inserted into the binder, together with the fuel pipe). This is how I found them in my 1991 Revere, but I found other models having the breather tube going to the right side, in a mirror-like way.
 {{.:honda_ntv650:ntv650-revere-carburetor-front-bottom.jpg?200|}}
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 {{.:honda_ntv650:ntv650-revere-carburetor-rear-bottom.jpg?200|}}
 {{.:honda_ntv650:ntv650-revere-carburetor-rear-top.jpg?200|}}
+===== Carburetors synchronization =====
+Remove tha tank and connect two vacuum gauges to the cylinders intakes using two joints plugs (Honda part 16214-MB0-000). Provide the fuel in some way, warm up the engine and adjust the idle speed (1100 +/- 100 rpm). The difference in vacuum reading should be 40 mm Hg or less.
+If necessary, synchronize to the specification by turning the synchronization adjusting screw: screwing-in by **turning clockwise will increase the idle of the rear cylinder**.
+{{.:honda_ntv650:sync-carb-ntv650-a.png?direct&280|Carburetors synchronization: Plug}}
+{{.:honda_ntv650:sync-carb-ntv650-b.png?direct&280|Carburetors synchronization: Joint plug}}
+{{.:honda_ntv650:sync-carb-ntv650-c.png?direct&280|Carburetors synchronization: Adjusting screw}}
 ===== The air cut off valve =====