I read this elsewhere, and thought it was worth
passing along. I now feel much more confident in
working on my carbs.
Since I have taken the morning off, I have a bit more
time than usual to help you. And what I have been
recently noticing is that a lot of you seem to be
having difficulties in getting the various carb jets /
engine matches to work well together. And I now think
that maybe we should all pause and take a step
backwards. Let's review just exactly how/why carbs
work. Having a more in depth understanding of the
basics of carb design and function will likely make it
far easier to get them set up correctly.
The basic secret of carb function is that inside each
carb are thousands of tiny gnomes; each with a small
bucket. As you open the throttle, more of these
gnomes are allowed out of their house and into the
float bowl, where they fill the buckets and climb up
the carb's passages to the intake, where they empty
their buckets into the air stream.
But, if you don't ride the bike for a while, bad
things can happen. Tiny bats take up residence in the
chambers of the carb, and before long the passages are
plugged up with guano. This creates a gnome traffic
jam, and so not enough bucketfuls of fuel can get to
the engine. If it gets bad enough, the gnomes simply
give up and go take a nap. The engine won't run at
all at this point. Sometimes you'll have a single
dedicated gnome still on the job, which is why the
bike will occasionally fire as the gnome tosses
his lone bucket load down the intake.
There has been some research into using tiny dwarves
in modern carbs. The advantage is that unlike gnomes,
dwarves are miners and can often re-open a clogged
passage. Unfortunately, dwarves have a natural fear
of earthquakes, as any miner should. In recent tests,
the engine vibrations caused the dwarves to evacuate
the Harley Davidson test vehicle and make a beeline
for the nearest BMW dealership. Sadly, BMW's are fuel
injected and so the poor dwarves met an unfortunate
end in the rollers of a Bosch fuel pump.
Other carb problems can also occur. If the level of
fuel in the float bowl rises too high, it will wipe
out the Section 8 gnome housing in the lower parts of
the carb. The more affluent gnomes build their homes
in the diaphragm chamber, and so are unaffected. This
is why the bike is said to be "running rich".
If the fuel bowl level drops, then the gnomes have to
walk farther to get a bucketful of fuel. This means
less fuel gets to the engine. Because the gnomes get
quite a workout from this additional distance, this
condition is known as "running lean".
The use of the device known only as the 'choke' has
finally been banned by PETG (People for the Ethical
Treatment of Gnomes) and replaced by a new carb
circuit that simply allows more gnomes to carry fuel
at once when the engine needs to start or warm up. In
the interests of decorum, I prefer not to explain how
the 'choke' operated. You would rather not know
So, that's how a carburetor works. You may wish to
join us here next week for electricity 101, or "How
your bike creates cold fusion inside the stator, and
why the government doesn't want you to know about it."
So, now you know the Ressssssst of The Story. No more
whining about jet sizing!