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--- tecnica:motori:honda_ntv650_carburetor [2024/09/24 12:31] – [Replacing the diaphragms at 100.000 and 200.000 km] niccolo
+++ tecnica:motori:honda_ntv650_carburetor [2025/12/19 13:08] (current) – [Repair kits] niccolo
@@ Line 25: / Line 25: @@
 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:carburetor-diaphragm-alignment.png?240|Diaphragm alignment}}
@@ Line 52: / Line 52: @@
 {{.: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 =====
@@ Line 62: / Line 73: @@
 Il circuito della valvola cut-off è un **condotto complementare al circuito del minimo** e contribuisce con una sua parte alla miscela aria-benzina per il corretto funzionamento del minimo. La differenza è che in tale circuito il condotto dell'aria può essere chiuso creando temporaneamente un maggiore apporto di benzina. La valvola cut-off viene azionata da una membrana collegata al condotto di aspirazione: quando la depressione è molto alta (alti regimi di rotazione e valvola a farfalla chiusa) la membrana fa chiudere il condotto dell'aria cut-off; il risultato è una miscela più ricca che evita l'afterburn. Quando il motore scende di giri la depressione diventa minore e la valvola cut-off torna nella posizione di riposo; il circuito del minimo viene quindi riportato alla condizione normale.
+===== Repair kits =====
+You can find several carburator **repair kits** on the net, many of them are no-branded, mainly Chinese production. What you want to replace mostly will be the **float chamber gasket** and the **valve needle**, whose rubber may have hardened and deformed. It is nice if the kit contains also the other o-rings.
+{{ .:honda_ntv650:kh-1348-box-back.jpg?120|Keyster KH-1348 kit}}
+{{ .:honda_ntv650:kh-1348-box-front.jpg?120|Keyster KH-1348 kit}}
+I found that several kits have low quality and/or low design parts, especially the float chamber gasket may be too thin or does not perfectly fit the cave. A nice exception is the kit from **Keyster**, a Japanese company specializing in carburetor restoration kits. I purchased the **KH-1348 kit** specifically produced for the Honda NTV650 Revere 1988-1990 and it turned out to be of **excellent quality**. The kit contains:
+  * 2 x Gasket chamber
+  * 2 x Valve seat with washer, filter and needle
+  * 2 x Screw air with spring, O-ring and washer
+  * 2 x Drain screw with O-ring
+  * 1 x Jet main #140
+  * 1 x Jet main #135
+  * 2 x Jet slow #42
+{{.:honda_ntv650:kh-1348-content.jpg?200|KH-1348 Kit Contents}}
+The kit **does not contain** the stem holding the main jet nor the little oval gasket of the air cut-off valve, but I was **particularly pleased with the float chamber gasket**: the shape and size are perfectly similar to the original.
+It seems that also the Keyster kit **K-976EK** is compatibile with the NTV650 Revere, it contains fewer parts, but it contains the same rubber parts as the **KH-1348** kit, plus the oval O-ring of the air cut-off valve. Another kit from Keyster is the **K139** (also labeled **NTMOR-007G**), which includes only the float chamber gasket.
 ===== Web References =====