QuestionI have a 07 yamaha virago. I used a fuel stabilizer but it still gummed up over the winter. I live in the rainy north west but kept the bike garaged and started it periodically. I took the carb off and cleaned it out good but it only idles when I give it any throttle it bogs out. I've reached in and manually pushed the accelerator plunger and nothing happens the passages are clear could it be the plunger? Or is there a different problem that's common and could cause this. The bikes got about 6000 miles and has had the valves adjusted. Thank you!
AnswerHi Josh,
You didn't mention if you had soaked
the carb in Yamaha carb cleaner.
If you didn't then the inner passageways
and jets could still be plugged up.
The jet in question that handles 1/4-3/4
throttle speeds is the tube or holder under
the center main jet.
This tube sometimes has small holes in it
to emulsify the raw fuel into a vapour.
If it is plugged you will have trouble
getting above idle. The same is true if
the main jet is plugged and it may need to
be cleaned physically with a small wire like a fine
guitar string to make sure it is clear.
I would also check the charging system
and battery as a poor battery or
faulty charging system may not provide
enough current to the engine computer.
Just check for 14-15 volts DC on the battery
terminals at a fast idle if possible.
If it reads under 13 volts then the charging system
needs work.
Occasionally other things can affect the
running such as faulty ignition switch
or side stand switch etc.
The center jets are more commonly the problem
or a plugged fuel filter or not
enough fuel supply from the tank.
The carb float level can be checked with a tube
on the drain which is held up to indicate the
internal fuel height in the carb bowl.
If the fuel is near the gasket line on the carb bowl
that is about right.
If the bike will rev up by covering the
carb mouth partially or the choke helps
then you have a lack of fuel supply
due to insufficient fuel or plugged carb.
A lack of fuel can also be due to a vacuum/air leak
on the carb mounting tube or intake which causes the engine to
draw in air instead of fuel.
If the carb is clean it should speed up when you
lift the throttle slide. You can also try some
starting fluid or carb cleaner in the
carb mouth to see if it is the fuel or not
that it needs. It should speed up when
you spray a bit in the carb intake.
If it speeds up then you know the ignition is
not at fault.
Always use a good spark plug and check the plug cap
for problems if the fuel seems okay.
Good luck!
Wayne S.
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