QuestionI recently purchased a 1985 Kawasaki Ninja 600R that had been parked since 1997(only 4531K original miles). I've finally got it started but the idle is never steady. It fluctuates at a range of about 500 rpms up and down. Another thing is that it will not start with the choke on, no matter how cold the engine is. I rebuilt the carbs but I'm still having this problem with the idle. What are some possible problems?
AnswerHi Sergio,
I suspect the synchronization screws were turned and causing the idle problem.
Review the Carb Cleaning 101 information below. Compare notes with your cleaning job. Re-clean the carbs if they were not cleaned thoroughly and synchronize when done.
Also check the gas tank for rust. The smallest rust particles will pass right through the fuel filters and become sediment in the float bowls. If rust is present, seal the tank with a product such as Kreem.
Respectfully,
Mark Shively
Carb Cleaning 101
By M. Shively
The elements of internal combustion engines are: correct fuel/air ratio, spark at right time, adequate cylinder compression.
There are many passageways and openings to check and clean. All are important in function and when obstructed or not working properly, have subtle to radical effects on engine performance. Vacuum leaks and carburetor synchronization also have effects on performance and should be inspected and adjusted following the below procedures.
Carb Cleaning 101
Warning: Remove all rubber parts before you begin. These parts usually include vacuum diaphragms, needle valves, orings, hoses, and other parts. Spray cleaners will damage these parts. Do not disassemble individual carbs from the carb bracket.
Air & Fuel Passageways: Trace and learn individual fuel and air circuits from beginning to end. Machines can only drill straight through the cast passageways. To change direction, another angled passageway must be drilled. The union is plugged with a brass or bronze bead. Inspect and clean each passageway with spray cleaner, brushes/pipe cleaners/etc, and compressed air. Remove any discoloration and debris. Look for spray cleaner to exit from one or more passageways.
Jet Cleaning: Inspect jets by holding to light and look through them. You should see an unobstructed round hole. Clean the jets with one or more of the following: jet cleaning wires, soak solutions, carb spray cleaners and compressed air. Re-inspect jets after cleaning and install when clear of obstructions. Some main jets have paper-like gaskets. Most have metal spacers between the jet and the emulsion tube. Some screw directly into a brass emulsion tube which is machined for a 7mm wrench at its float chamber exposed base.
Inlet Fuel Valve: Inspect the needle valve & spring. Press down the tiny metal rod that protrudes from the butt or float end of the needle valve. The spring should move freely and return the rod to its location. Check the needle valve's seat area for a groove or other wear. It should appear highly polished. Some needle valve seats are rubber and wear may not be visible. Inspect the needle valve jet seat. You can clean the jet seat with Q-tips and semi-chrome polish if necessary.
Carb Body Castings: Blow air through the atmospheric vent holes located on the dome of each float bowl chamber. Air should exit via hoses or brass nipples. Inspect the emulsion tubes and passageways (cast towers that jets thread into) for discoloration and debris. Clean interior emulsion towers with a soft bristle gun cleaning brush. Clean the Venturi's (main carb bore).
Needle Jets & Jet Needles: Clean the needle jets, jet needles, and passageway or tower that needle jet screws into. Clean the emulsion tube (pipe between needle jet and main jet) (Main Jet may screw into emulsion tube). Jet needles are part of the throttle slides. See below…
Throttle Slides: There are several types of throttle slides: Mechanical linkage, vacuum, diaphragm, and cable. Disassembling the jet needle from the slide is not always required for cleaning. If you have vacuum piston type throttle slides (large diameter solid metal slide), avoid cleaning the lubrication from sides and caps. If piston type check cap vents and passageways with air. Clean if necessary and re-lube. If you have rubber vacuum throttle diaphragms, inspect for dry-rot, defects, and tears by gently stretching rubber away from center. Do this until all areas around diaphragm have been inspected. Replace any defective part as described above. Clean carb body areas around diaphragm including air passageways and air jets. Diaphragms have a locator loop or tab fabricated into their sealing edge. Observe this locator upon reassembly. Avoid pinching the diaphragm when reinstalling caps.
Fuel Screws: Fuel screws have sharp tapered ends. Carefully turn one fuel screw in while counting the turns until it seats lightly. Warning: These screws are very easily damaged if over tightened into their seats. Record amount of "turns-in" and remove the fuel screw, spring, washer, and oring. The fuel screw is part of the enrichment (choke) circuit...clean passageways as described above. When carbs are assembled, spray low PSI compressed air into diaphragm air vents located at intake side of carbs. Throttle slides should rise, then fall when air is removed. Lightly lube external moving linkages. Reinstall carbs and follow through with carburetor synchronization.
Throttle Cables: Lubricate cables periodically. If cables are disconnected from carbs or removed for replacement, etc . . . remember cable routing and ensure proper reinstallation routing. Avoid bread-tying, sharp bends, and pinching cables. Adjust cables so throttle grip has about 5mm of play or throttle slides or butterfly valves may not open completely (full throttle)(wide full open).
Float Bowls: Inspect float bowls for sediment, gum or varnish, crystallization, and defects. Clean all pipes, tubes, passageways, and embedded jets with cleaners and compressed air. Remove and clean the drain screw and area. Inspect bowl gasket and replace if necessary. Clean and inspect overflow pipes and tubes, look for vertical cracks.
Floats: There are several types of float materials: plastic, brass, black composite, tin, and others. Handle floats carefully. Avoid bending, twisting, denting, or other means of mishandling. Most floats are adjustable by bending a small metal tab near the float axle end. Do not change the float adjuster tab unless tuning fuel service levels. Clean metal floats by soaking or spray cleaners, if necessary. Replace other type floats if cleaning is necessary. Clean the float axle or pin.
Synchronization: This is a fine adjustment performed usually and preferably with the carbs installed and the engine running. The unusual part is performed with gauged wire with the carbs on the work bench. Carburetor synchronizing balances Venturi vacuum at the exhaust side of each carburetor, resulting with smooth idling and optimized performance at all throttle openings. Synchronization is checked using a set of gauges which are either air vacuum type or liquid mercury type. The gauges are connected to vacuum ports on the intake manifolds via nipple tubes or if sealed with screws, sync gauge adapters will be needed. With the engine running at temperature, and with a fan or means of forced convection aimed onto the engine, the carbs fuel screws and idle are adjusted, then the synchronization is adjusted via adjustment screws on the carbs. A reserve fuel tank is recommended for convenience of accessing carbs during this procedure. See gauge instructions and repair manuals for detailed use of synchronization gauges.
Notes: While carbs are apart, record the jet sizes. Look for a very small number imprinted on the body of the jets. It should be the same number for all. If you have dial or veneer calipers, measure and record float heights. Perform measurements with floats just touching needle valves, though not depressing the needle valve rods. Replace fuel and vacuum hoses. Be sure to use fuel rated hose for fuel. Install or replace in-line fuel filters. It's a good time to remove and clean interior petcock fuel filters. Inspect carb manifolds for dry-rotting, inspect all clamps and air ducts. Inspect, clean, lube, and/or replace air filter(s).
Carb Maintenance & Synchronization
Experiencing rough idle, galloping, backfire, and uneven acceleration? This is a good indication you need the carbs synchronized. The procedure is fairly similar for all multi carb engines including Goldwings, V-max and a great many more. The idea is to get all the individual cylinder vacuums to match. I'll use the standard inline four as a demo type. First thing pull the seat & fuel tank so you can get at the carb adjustments and vacuum connections. You'll need an auxiliary fuel supply as the tuning will take enough time to drain the carbs dry. Here's a neat little tank that will do the job with minor cash outlay. (Image not available on AllExperts question format).
Fill the auxiliary tank about 1/2 full. Slip the hose over the spout tip. There's no need to vent the tank as the sides are soft and will "inhale" as fuel is used. Hook up the tank to one of the fuel lines (some bikes have (2) lines that feed all the carbs, one is standard the other is reserve. Using a 1/4" drill bit or short Phillips screwdriver, plug the remaining lines so fuel doesn't spray all over. Lay the tank on the frame or faring just so gravity can do its thing. Start with the idle fuel mixture settings. Check the service manual for how many turns out the mixture screws are supposed to be set. (Some mixture screws are non-adjustable. Skip this step and go to synchronization). Start engine & allow it to warm up. Place a fan or furnace blower in front of the engine to keep from overheating. (Mixture screw tips are precision machined points and may be easily damaged if tightened into seats). One screw at a time, turn mixture screws in until they seat, counting number of “turns in” as you go. Record this number for later reference if needed. Once seated, back them out to factory recommendations. Turn the screw on #1 carb out until you notice a roughening idle. Go back to the original setting and turn in until the idle roughens again. Set the screw at the mid point of these two settings. Repeat with other mixture screws. Some carbs use a fuel mixture screw and some use an air bleed screw. The procedure is the same for both. On the fuel mixture screw type, turning screws clockwise is leaner; counter clockwise is richer. The air bleed type is just the opposite.
Carburetor Synchronization:
To sync the carbs you will need a gauge set or one of the more popular carb stick synchronizers. These can be purchased through "Dennis Kirk" 1-800-328-9280 or www.JCWhitney.com, (Keyword: Carburetor Synchronizers). Most tuners prefer the mercury carb sticks as they are more reliable in the long term and don't require any needle flutter calibration. Hose adapters are required for some motorcycles. They are not included with the tool and are a separate purchase. They are listed with the sync tools. I recommend the purchase of a sync adjuster screw tool. This tool works the locknuts and adjuster screws.
Support the sync tool on a lever or handle bar grip and connected to the respective carbs. Keep the hoses clear of engine's hot surfaces. For tuning Yamahas, go to the "YICS" section for the tuning procedure.
With fan on in a well ventilated room or area, aux fuel connected, idle mixture set, and carburetor synchronizer tool connected, and engine warmed to normal operating temperatures, set the idle speed to about 1000 RPM and watch the sync gauges. Pick a carb and set the vacuum of the others to match this one. Pick one that is not the highest or lowest, but in the middle of the readings. Some carburetors have one non-adjustable carb that the others are adjusted to. Check the service manual or call your local dealer if you are not sure if your carbs are this type.
The majority carbs have adjusting screws between the carbs. (On older Kawasaki KZ type carbs, adjusting screws are located under the carburetor top cover caps.) Adjusting screws have locknuts to maintain adjustments. You may notice your adjustments change slightly when tightening locknuts. Compensate for this accordingly as you work. The adjuster found between carbs 1 & 2 balances those two carbs. The adjuster found between carbs 3 & 4 balances those two carbs. The adjuster found between carbs 2 & 3 (or center) balances the left and right carb sets (1-2 & 3-4) to each other. On older Goldwings, screws are between carbs as above, but center adjuster is on the left side. The order in which the carbs are adjusted doesn't matter as long as they all come out balanced in the end. When adjusted as level as possible, you're finished.
Sync adjuster screws may have a drop of red or yellow paint to mark or seal the factory sync settings. While synchronizing, open and close the throttle slowly to avoid drawing mercury into the engine.
