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--- tecnica:motori:honda_ntv650_carburetor [2025/12/19 10:45] – [Repair kits] niccolo
+++ tecnica:motori:honda_ntv650_carburetor [2026/04/08 22:34] (current) – [Problem with the Keyster valve seat] niccolo
@@ Line 46: / Line 46: @@
 ===== 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 (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.
+In the following photos you can see how the fuel line and the breather tube are positioned around the carburetors.
+{{.:honda_ntv650:ntv650-revere-carburetor-a.jpg?200|}}
+{{.:honda_ntv650:ntv650-revere-carburetor-b.jpg?200|}}
+{{.:honda_ntv650:ntv650-revere-carburetor-c.jpg?200|}}
+{{.:honda_ntv650:ntv650-revere-carburetor-d.jpg?200|}}
+The above is how I found the tubes in my **1988 NTV650J** Revere, but I have also a **1989 NTV650K** that has the breather tube going to the left side, in a mirror-like way. In this case the binder bracket on the right top cover can accommodate the choke cable.
-{{.:honda_ntv650:ntv650-revere-carburetor-front-bottom.jpg?200|}}
 {{.:honda_ntv650:ntv650-revere-carburetor-front-top.jpg?200|}}
-{{.:honda_ntv650:ntv650-revere-carburetor-rear-bottom.jpg?200|}}
 {{.:honda_ntv650:ntv650-revere-carburetor-rear-top.jpg?200|}}
 ===== Carburetors synchronization =====
@@ Line 85: / Line 91: @@
   * 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.
+===== Problem with the Keyster valve seat =====
+After overhauling the carburetors with the Keyster kit, I had **a problem with the float valve seat**. Even though I had adjusted the float level according to the manual (9.2 mm), after driving for a few kilometers, the fuel began dripping from the carburetor vent tube. Evidently the valve wasn't closing, and **the float chamber was overfilling**.
+To confirm that the fuel level was the problem, I connected two clear rubber hoses to the carburetor drains. The hoses were then bent upward, above the fuel cap. By loosening the **drain screws** of the carburetors, you can see the fuel level in the hose, which will be equal to the level in the float chamber. After a few kilometers of driving, I confirmed that the level in one of the two carburetors had risen several centimeters and was now reaching the breather pipe.
+{{.:honda_ntv650:keihin-carburetor-inspecting-fuel-level-in-float-chamber.jpg?direct&400|Inspecting the fuel level in float chamber}}
+When I removed the carburetor, I noticed that **the Keyster replacement had different dimensions than the original**, both the valve seat and the washer. To be safe, I reassembled the originals, and the problem was solved.
+{{.:honda_ntv650:keihin-carburetor-valve-seat.jpg?direct&400|}}
+{{.:honda_ntv650:keihin-valve-seat-honda-original.jpg?direct&280|}}
+{{.:honda_ntv650:keihin-valve-seat-keyster-replacement.jpg?direct&280|}}
+{{.:honda_ntv650:keihin-valve-seat-washer-honda-original.jpg?direct&280|}}
+{{.:honda_ntv650:keihin-valve-seat-washer-keyster-replacement.jpg?direct&280|}}
+===== Do not use red paste gasket sealant! =====
+I once installed a float chamber gasket whose size I didn't trust, so I added some **red gasket sealant**, by **Würth**. The result was disastrous: after less than a year and about 2000 km, the red paste dissolved in the fuel and formed a sludge in the carburetor float chamber. Naturally, the bike began to have idle problems and backfiring. Cleaning the inside of the carburetor was a pain, luckily **nitro thinner** seems to dissolve this red sludge.
+{{.:honda_ntv650:carburetor-red-paste-gasket-a.jpg?200|}}
+{{.:honda_ntv650:carburetor-red-paste-gasket-b.jpg?200|}}
-The kit **does not contain** the stem holding the main jet nor the little oval gasket of the air cut-off valve.
 ===== Web References =====