The first thing you should do is find out what size jets you need
to install. If everything is stock then you will need 40 pilots, and 125
mains, and one washer to raise the needle, also the idle air screw out 3
turns. Other than that you will need to ask around to determine what
size you need. The jets should cost ~$2.50 Brand New and the washer is a
#4 washer (stainless steel or Brass) which you have to go to a hardware
store to get, Just ask for a #4 washer (theyre pretty small) $0.07 apiece.
Approximate time for someone who has torn apart the bike before. 2hrs
NOOB time. 3-4hrs.
Read the directions all the way through a few times to get a feel for
what you have to do before you get stuck.
Jump to step 8 if you know how to remove the carbs.
Remove the seat.
Remove the plastic sides of the seat. Two bolts that bolt to the
frame and then the two screws holding on the piece under the rear grab
Remove the two bolts holding on the tank. Slide the tank back a
little bit so the front hook is not under the frame anymore and tilt
the tank back and use a Flat head screwdriver to turn off the petcock
under the tank. You need to come from the right side of the tank
almost all the way to the other side. Just a note having the slot
facing with the direction of the tubes is on, perpendicular is off.
Remove the 2 hoses from the tank (be careful they are filled with
fuel), there is also a drain hose attatched to the tank towards
the back, you can either remove this or just pull it out along with
the tank (not critical). now grab under the rear of the tank and
the nose and place the tank in a safe spot. Be careful to make sure
that the tank petcock does not get damaged when you put the tank
somewhere. I propped mine up against a toolbox so the front end was
off the ground.
I found it easier to remove the airbox without the fuel valve in the
frame. So take a socket and remove the bolt holding the fuel valve and
just let it hang in the frame. Now there are two screws holding the
airbox in the frame which are just underneath the frame at the rear of
the airbox. With those screws out you now need to loosen the clamps
holding the airbox to the Carb. It is basically a big hose clamp
sealing the airbox to the carb, loosen those clamps almost all the way
off then pull the airbox toward the battery until you feel/see it come
off of the carburetors, then lift it up and out.
Now would be a good time to drain each carb also. (little screw on
each carb facing out with a little hole underneath, dispose of fuel
that comes out of the carbs) Now remove the Vacuum hose from the Fuel
Valve (I found this easier than removing it from the carbs) then
disconnect the throttle cable (middle of the carbs) and the Choke
cable (right side of the carbs), The drain tube (top center of the
carbs) and then finally the fuel line (bottom center of carbs).
Everything should now be disconnected from the carbs except the
vacuum hose. Now there are 2 more hose clamps holding the carbs to the
intake manifolds. Loosen those two clamps almost 100% just like before
and slowly pull the carbs toward the battery until it comes off.
First lets install the washer. With the carbs oriented the way they
were mounted on the bike you should see two big black plastic caps,
One on each carb. Take a screw driver and remove the screws holding
one cap on (do the carbs one side at a time), slowly lift the cap off
the carb. Make sure you dont lose any orings seals or anything. Now
there should be a spring attached to the cap. Now you might be able to
get the needle out by tipping the carb upside down, if not slowly work
up the little rubber diaphragm and pull the slide out. You are trying
to get at the long brass needle in the center. Now with the needle in
your hand pop off the little C clip and the washer goes underneath
that, so you might have to push down the plastic doughnut that was
under the C clip. Basically work with it until you have the needle
with the plastic doughnut, #4 washer, C clip. Then reinstall
everything and do the same to the other side.
Now the main/pilot jets. After you have finished the top of the
carbs flip them over so your now looking at the bottom. Each float
bowl has 2 screws holding it on, Remove the 2 screws and pull off the
float, make sure you dont damage any seals. Now you will see the float
(big orange structure) and the float needle (small brass piece that
looks like a midget pencil). Grab the float and pull it straight up
and set it on your workbench trying to keep it exactly as it came out.
Now looking back at the carb you will see the main jet (see photo)
just unscrew it with a flathead and install the new one. Now look in
close vicinity to the main jet you should see a small hole with the
pilot jet (see photo) just do the same thing as above.
Lastly the Idle air screw. This is hidden behind a brass plug
that needs to be drilled out. Carefully use a small drill bit in
the center of the plug to make a small hole. After you have a
small hole take a drywall screw or something similar and thread it
into the hole and pull out the plug. Seat the screw all the way
down then back it out 3 complete turns.
I suggest installing an Inline filter while you have the fuel system
apart. Go buy an inline filter for like $2.50 and just splice it into
the fuel line that goes to the bottom T of the carburetors (note the
direction of the arrow on the filter).
Finally put everything back the way it was before. Set idle to 1,200
and enjoy a Linear torque curve!!!
note on reassembly- Alternatively when reinstalling the carburators mount
the carbs into the aribox so you do not have to fiddle with trying to seal
the airbox onto the carbs while in the frame. - Thanks to Lars from
Looking for info on the fuel hose routing?