I've inherited a 1985 Virago 1000 with 16000 miles on the speedo. It will only run rough with the choke on. I replaced the battery with a new one when I got the bike. Since then I cleaned the carbs,...
the carburetors will
need thoroughly cleaned and related rubber vacuum and fuel hoses will need
replaced. Use fuel rated hose on fuel lines.
Gasoline goes bad with
time and in as little as 3-4 weeks. This effect is known as varnishing. Jets
and passageways within carburetors become obstructed when varnishing
Liquid gasoline changes chemically into a gel like substance. Advanced stages
of varnishing results with the solid gel changing into a crystal powder
substance. Interior carb surfaces are etched in the process and may require
The choke and pilot circuits with most motorcycle carburetors share
passageways. When pilot jets become obstructed, the choke circuit compensates
and allows engine to start and idle with choke, but stalls without choke.
FOR MORE HELP:---
Carb Cleaning 101
The elements of internal combustion engines are; correct fuel/air ratio, spark
at right time, adequate cylinder compression. Motorcycle and ATV carburetors
have many passageways and openings to check and clean. Subtle to radical
effects on engine performance occur when jets and passageways become
obstructed. Vacuum leaks and carburetor synchronization also effect performance
and should be checked and adjusted. The following procedures are a helpful
Carb Cleaning 101:----Warning: Remove all rubber (Neoprene) parts before
applying chemicals to carburetor parts. These parts usually include vacuum
diaphragms, needle valves, o’rings, hoses, and other parts. Spray cleaners may
damage these parts. Do not disassemble individual carbs from the carb brackets.
Air & Fuel Passageways: Trace individual fuel and air circuit passageways
from beginning to end. Machines can only drill straight paths through castings
to form passageways. A change of direction or angle means drilling additional
connecting passageways. Access holes left by the drilling process are plugged
with brass or bronze beads. Inspect and clean each passageway with spray
cleaner, brushes, pipe cleaners, and compressed air. Many household items can
be useful cleaning tools. Remove any discoloration and debris from carbs. Look
for carb spray cleaner to exit from one or more passageways. Chase immediately
with compressed air.
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
Inlet Fuel Valve: Inspect the needle valve & spring. Press down the tiny
metal rod that protrudes from the **** 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 each Venturi (main carb bore).
Needle Jets & Jet Needles: Clean the needle jets, jet needles, and emulsion
tower (main 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 o'ring. 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.
This will help. Thanks please keep updated.please do
rate the solution positively .thank you for using fixya
Apr 20, 2010 |
Yamaha V Star 1100 Classic Motorcycles