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Introduction:
At this point, you should
have removed the airbox, the old carburetor, the manifold,
the reed cage, and the old throttle cable. It is also
a good idea to de-restrict the stock reed cage (see
step 3 and picture 1). Do
not install the new throttle cable on the carburetor at this
time. The carburetor should be disassembled to the stage
as seen in picture 6. The
slide needs to be out of the carburetor body. There is
a specific order that the carburetor install must proceed. If
your manifold (Mikuni 24mm kit with 19mm manifold) has a mysterious
hole in it, this is where the oil injection spigot goes. The
old oil injection spigot must be removed from the old 12mm carburetor. It
is just press-fit in. Use some gasket sealant on it and
install it in the 19mm manifold. Lightly tap into place
with a metal hammer. If you plan to run pre-mix only oiling,
then you must come up with a way to block-off the oil injection
spigot. It cannot leak air. Also remember, carburetor
settings differ greatly between oil injection and pre-mix.
Installing
the reed cage and manifold:
Re-install the reed cage,
and bolt on the new manifold (see
picture 2). Be sure to install the ground wires to
the top left bolt, and the clutch cable holder to the lower
right side bolt.
Throttle
Cable Installation:
To install the new throttle
cable, first the oil pump must be disconnected (see
step 3 and picture 3). Then
the cable splitter can be pulled apart. Install the new
throttle cable into the splitter (see
picture 4). Loop the cable ends into their respective slots
inside the junction block (see picture
5). Close the cable splitter. You can now re-install
the oil pump cable (see picture 13)
back onto the oil pump. To continue installing the carburetor,
first the carburetor top must be installed on the cable (see
picture 7). Use all the supplied rubber boots, as
this can be a source of an intake air leak.
Throttle
Cable to Carburetor Slide Installation:
With the e-clip installed
onto the needle, install the needle into the middle hole
in the carburetor slide (see picture
8). Next install the carburetor slide spring over
the throttle cable. Pull the cable end through the
middle. With your hand or carefully with a pair of
pliers, hold the spring compressed and grab the free cable
end. Next, install the white needle hold down part
(spring perch) over the free cable end. Put the free
cable end into the slot in the slide body (see
slot in picture 8). Slowly release the spring tension. Make
sure the plastic part is fully seated. The finished
result will look like picture 9. The
order of the parts threaded onto the throttle cable are the
carburetor top, gasket (small o-ring on Dell-Orto 21mm and
a paper gasket on a Mikuni 24mm), slide spring, spring perch,
and finally the slide.
Finishing
Up:
Carefully install the
slide into the carburetor body. It can only go in one
direction. Be careful with the needle. It needs
to be inserted into the emulsion tube (see
picture 10). Do not force the slide down. Install
the two carburetor top screws. Now is a good time to
test the throttle action at the grip. Ensure that the
slide goes up and down smoothly and fully. It should
move very smoothly and return on its own. If not, check
cable routing, and for other sources on binding. This
can be very dangerous, if not fixed. It could lead
to a stuck wide open throttle.
Install
the carburetor to the manifold insuring an airtight seal. Attach the
oil injection line (cap off injection spigot for pre-mix running
engines). Notice where the fuel line attaches (see
picture 11). Finally install the inlet adaptor,
and either the airbox or pod air filter. Note, carburetor
settings differ greatly when running the stock airbox versus
a pod-style (clamp-on) air filter. The 21mm Dell-Orto
kit comes pre-jetted for the stock airbox and oil injection. Using
a pod filter will require significantly richer jetting. Running
pre-mix will also require richer jetting.
Adjustments:
Note the positions of the
air/ fuel mixture screw and idle speed adjustment on the Dell-Orto
21mm as shown (see picture 12). Also,
note the vent line which must simply be vented to the atmosphere
(see picture 12). Note
on other types of carburetors there maybe more than one vent
line. The Mikuni 24mm carburetor idle speed adjuster and
idle air/ fuel screw adjusters look very similar.
To
lower your idle speed, rotate the adjuster counter-clockwise
(loosen). To
raise your idle speed, rotate the adjuster, clockwise (tighten). A
couple of small turns is all that is every really needed.
To
richen the idle and low speed mixture, rotate the adjuster
counter-clockwise
out with 1/4 turn increments. To lean out the mixture,
rotate the adjuster clockwise in 1/4 turn at a time.
Note
that the idle mixture screw does NOT affect any RPM greater
than just
off-idle. It will not cure a lean or rich wide-open
or part-throttle running condition. This adjustment
is made with mainly with main jets, needle clip position,
and to a lesser extent the pilot (slow) jet.
Tuning and Final
setup is the next chapter.......
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