QuestionThanks Mark, that's my plan for today, to clean the carbs.
However, here's a question.
In reading a bit since I e-mailed you earlier, what is the possibility that this is not a carb issue, but rather a problem with the vacuum petcock?
Thanks, Paul
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Followup To
Question -
I had the carbs on my 84 LTD1100 changed for some older Mikuni carbs last fall.
However, now the bike initially starts fine with or without the choke, but when riding it seems to struggle for gas, and then stalls.
There is a lot of gas that streams out of the bottom of the air box, and the plugs are getting fouled and flooded.
What causes the flooding? And how can I fix this?
Answer -
Hi Paul,
Q: ...the bike initially starts fine with or without the choke, but when riding it seems to struggle for gas, and then stalls.
A: The carburetors must be tuned to work with this engine.
Q: There is a lot of gas that streams out of the bottom of the air box, and the plugs are getting fouled and flooded.
A: The needle valves (float valves) are worn, sticking, and/or varnish & rust particles are caught between the needle valve and needle valve seat preventing the valve from closing. This allows fuel to over fill the float bowls. Fuel then flows up through the carbs and into the airbox and crankcase.
Q:What causes the flooding?
A: See above answer.
Q: How can I fix this?
A: The carbs must be removed, thoroughly cleaned, and reinstalled. The fuel tank may need to "Kreemed" lined to remove and seal rust. See the information file below.
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).
AnswerPaul,
It's a possibility. Even a pinched fuel hose could cause such symptoms.
Use my email for follow-ups: mshively1@woh.rr.com
Mark
Kawasaki installed vacuum petcocks on a couple model years of early Ninja's with an off position on the petcock dial. Again, they were not gravity fed petcocks. Blame it on supply and manufacturing costs, if you will. Maybe a prior owner of the Vulcan changed the petcock.
Kawasaki's replacement petcock for various year/model vacuum petcocks is a gravity type petcock from the old KZ900's, part #51023-057. If you can find a new vacuum type in a dealer's parts bin, you're in business. You can not order certain Kaw vacuum petcocks any longer. Fortunately for us, Kaw parts interchange well.
BYW...vacuum petcocks can "stick open" when defective. If stuck open, they act like a gravity fed petcock left in the on position, and may cause leaking as such.
The amount of fuel in a tank is irrelevant to the pressure of the fuel on the float valves. Pressure from the tank, thru the lines, to the valves remain constant. If not, at what pressures or capacity of fluids do the floats then fail? or hoses and fittings fail? The pressure of gravity itself is enough to cause floats to wear. Cruddlings <--(coined by MAC_MUZ) cause the fuel to free flow past the valve, and out the shortest path of resistance, usually the overflow tubes. When flow doesn't meet demand, fuel flows thru next path in the chain. Usually flow travels up thru the main emulsion tower/main jet to the Venturi, and depending on angle, fuel flows West to the air box, or East to the head/cylinders, or both.
Air boxes have drain holes and a large drain tube for the collected regursion oil/gas sludge. The hose may be capped and drainage is part of routine maintanence. As Bluepoof mentioned, these tubes are often loaded and create an unpleasant experience for the unsuspecting person performing service.
