1. 

   6.1 Carburettor drain screw (arrowed)

   If the engine runs extremely rough at idle or continually stalls, and if a carburettor overhaul does not cure the problem (and it definitely is a carburation problem - see Section 6), the pilot screws may require adjustment. It is worth noting at this point that unless you have the experience to carry this out it is best to entrust the task to a motorcycle dealer, tuner or fuel systems specialist. The pilot screws are fairly accessible on this engine (see illustration), although an adjuster tool (long thin flexible drive screwdriver with an angled end) can be obtained if access is difficult.

2. Before adjusting the pilot screws, warm the

engine up to normal working temperature. Screw in the pilot screw on both carburettors until they seat lightly, then back them out to the number of turns specified (see this Chapter's Specifications). This is the base position for adjustment.

3. Start the engine and reset the idle speed to the correct level (see Chapter 1). Working on one carburettor at a time, turn the pilot screw by a small amount either side of this position to find the point at which the highest consistent idle speed is obtained. When you've reached this position, reset the idle speed to the specified amount (see Chapter 1). Repeat on the other carburettor.

4. Due to the increased emphasis on controlling exhaust emissions in certain world markets, regulations have been formulated which prevent adjustment of the air/fuel mixture. On such models the pilot screw positions are pre­set at the factory and in some cases have a limiter cap fitted to prevent tampering. Where adjustment is possible, it can only be made in conjunction with an exhaust gas analyser to ensure that the machine does not exceed the emissions regulations. Note: On some carburettors a special Honda service tool (pt. no. 07KM A - MS60101) is required to engage the pilot screw heads.

5 Carburettor overhaul -

general information

6.2 Crankcase breather hose (a), carburettor breather hose (b) and sub-air cleaner hose (c)

1. Poor engine performance, hesitation, hard starting, stalling, flooding and backfiring are all signs that carburettor maintenance may be required.

2. Keep in mind that many so-called carburettor problems are really not carburettor problems at all, but mechanical problems within the engine or ignition system malfunctions. Try to establish for certain that the carburettors are in need of maintenance before beginning a major overhaul.

3. Check the fuel tap and filters, the fuel hoses, the inlet manifold joint clamps, the air filter, the ignition system, the spark plugs and carburettor synchronisation before assuming that a carburettor overhaul is required.

4. Most carburettor problems are caused by dirt particles, varnish and other deposits which build up in and block the fuel and air passages. Also, in time, gaskets and O-rlngs shrink or deteriorate and cause fuel and air leaks which lead to poor performance.

5. When overhauling the carburettors, disassemble them completely and clean the parts thoroughly with a carburettor cleaning solvent and dry them with filtered, unlubricated compressed air. Blow through the fuel and air passages with compressed air to force out any dirt that may have been loosened but not removed by the solvent. Once the cleaning process is complete, reassemble the carburettors using new gaskets and O-rings.

6. Before disassembling the carburettors, make sure you have all necessary gaskets and O-rings, some carburettor cleaner, a supply of clean rag, some means of blowing out the carburettor passages and a clean place to work. It is recommended that only one carburettor be overhauled at a time to avoid mixing up parts.

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Carburettors -

removal and installation

Warning: Refer to the precautions given in Section 1 before starting work.

Removal