![Page 1: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/1.jpg)
By Ed Ness
CV Carburetor Rebuild Tutorial
![Page 2: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/2.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
• This tutorial is intended to assist folks rebuilding
their GS Suzuki CV type carburetors.
• Starting in 1980 (in the US market anyway) all
GS bikes adopted Mikuni BS (CV) carburetors.
• These carburetors came in three sizes
(denotation reflects the inside throat diameter by
the butterfly throttle valve):
– BS32 (32mm) for GS550, 650, 750, 850
– BS34 (34 mm) for GS1000 & 1100 – also 450
(although the 450 configuration is somewhat
different)
– BS36 (36 mm) for the GS1150
![Page 3: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/3.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Required Tools
#3
Phillips
#2
Phillips
14 mm10 mm
8 mm
Use of JIS
screwdrivers
get the best bite
on Japanese
screws
![Page 4: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/4.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Screwdriver blades need to fit snug into slots otherwise
screw can get stripped. If these screws seem stuck, do NOT
force them, use penetrating lubricant, such as PB Blaster,
and a heat gun on the carb body, then try again.
Screwdriver blade should be
.0385” thick at tip for removing
pilot screw
Screwdriver blade should be
.0350” thick at tip for
removing pilot jet
![Page 5: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/5.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Fuel
height
gauge
Cut off disc
Optional Tools
![Page 6: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/6.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Required Tools
• #2 Phillips screwdriver (JIS type recommended) – various uses
• #3 Phillips screwdriver (JIS type recommended) – lower gang plate screws
• Needlenose pliers – R/R float needle seat and fuel jet
• Nail setting punch (small tip) – driving out float pin
• ¼” drive socket (approx. 5/32” or 6mm size) – support float post while removing pin
• Large blade screwdriver – R/R main jet
• Small blade screwdriver – R/R pilot screw (must fit tightly into slot)
• Small blade screwdriver – R/R pilot jet (must fit tightly into slot)
• Calipers (or accurate scale) – to set float height
• 14mm wrench – R/R choke plunger
• 10mm wrench – R/R floatbowl drain screw
• Xacto knife (or very small blade screwdriver) – to remove O-rings
Optional Tools
• Drill motor or dremmel tool – to drill out pilot screw cap or slot screw
• Dremmel cut off tool – to slot screws
• Vice grips – removing stubborn screws
• Drill bit – drill out pilot screw cap (5/64” or similar)
• Wood/sheet metal screw – extracting pilot screw cap
• Impact driver w/ #2 & #3 Phillips bits – removing stubborn screws
• Hammer – for smacking impact driver or tapping punch to remove float pin
• Toothbrush – scrubbing dirty parts
• Fuel measurement tool
• Long nose snap ring pliers – R/R carb needle C-clip (Motion Pro 08-0279 shown)
For you guys that like a list6
![Page 7: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/7.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
For those pesky screws that
the previous owner stripped.
Impact Driver
![Page 8: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/8.jpg)
Mikuni BS (CV) Carburetor Rebuild TutorialLast resort6
Cut slot in screw6
Remove with
blade
screwdriver
![Page 9: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/9.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
For lubrication of O-rings
(motor oil is OK too)
Materials
In places where carb dip is not legal, this
Yamaha product can often be obtained
P/N ACC-CARBC-LE-NR
Last resort if carb
dip can not be
obtained is to boil
parts in mild Pine-
Sol or lemon juice
mixture
![Page 10: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/10.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Cycleorings.com kit
Optional Viton O-rings (thick X ID)
Choke plunger: 1.5mm X 10mm
Drain bolt: 1.5mm X 5mm
Float Needle: 1.6mm X 7.1mm
Fuel Tubes: -10 size (1.8mm X 6mm)
Pilot Screw: 1.13mm X 2.70 mm or
optional (1.0mm X 2.5mm)
MaterialsThe original Mikuni brass parts (jets,
float valve, etc) are very high quality.
Reuse these parts unless damaged.
Aftermarket “carb kits” are typically
of lesser quality and the included jets
are often generic and not specific to
each bike model.
Intake Pipe (boot) O-rings
should be refreshed when
rebuilding carbs!!!
![Page 11: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/11.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
BS36’s from Suzuki GS1150
Carbs # from LH to RH as sitting on bike
#1#2#3#4
Note: before beginning work
you may want to degrease the
carbs to avoid mess and
contamination of your carb
dip when you get to that point.
#4#3#2#1
Engine side
These numbers may appear
backwards because this photo is
looking back at engine side of carbs
![Page 12: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/12.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Mark carb bodies
with position
numbers
![Page 13: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/13.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Suzuki pressed an aluminum cap over the pilot
screw that needs to be removed
![Page 14: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/14.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Drill bit has tape applied so drill doesn’t go too deep
(5.5 mm deep max.) and hit pilot screw under cap
![Page 15: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/15.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Drill into cap, only to
the depth of the tape
![Page 16: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/16.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
![Page 17: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/17.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
1) Insert screw into hole
and tighten – cap may
start to turn which is OK
2) Grab screw with
pliers and pull out cap
![Page 18: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/18.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
![Page 19: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/19.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Pilot screw is visible once cap is
removed
![Page 20: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/20.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Choke actuation components need to be removed
Remove screws securing choke levers to rod
![Page 21: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/21.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Once screws are loose choke rod can be pulled
out to the side and the choke levers removed
Slide to remove
![Page 22: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/22.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Choke actuation components
removed
![Page 23: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/23.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove top cover screws (4 carbs) and
extract slides and springs
![Page 24: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/24.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Inspect slide
diaphragms
carefully for tears
and holes
![Page 25: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/25.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Top cap, slide and spring removed
![Page 26: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/26.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
To un-gang the carbs these screws need to be removed
![Page 27: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/27.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
![Page 28: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/28.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove screws
![Page 29: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/29.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Carbs can now be un-ganged
![Page 30: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/30.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Fuel inlet T
Fuel transfer tubes
– between #1 & #2,
and #3 & #4
Breather interconnect tubes –
many GS bikes have T-fittings
w/hose instead
![Page 31: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/31.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove pilot screw –
anti-seize or grease on
threads is recommended
during reinstall
![Page 32: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/32.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
O-ring and washer often
hang up inside the carb
body and must be
extracted from down in
pilot screw tunnel
Bend piece of wire like this and
go fishing
![Page 33: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/33.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Removing choke plunger
14mm
hex
![Page 34: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/34.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
![Page 35: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/35.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove screws and
then float bowl
Remove gasket
carefully and
try to salvage
![Page 36: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/36.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove pilot jet plug
(replace if petrified)
The pilot jet is located down in the
recess tunnel under the plug. A
tight fitting screwdriver is required
to remove these jets. Caution: do
not strip slot in head. If screw is
tight, do not force. Use penetrating
oil and heat, and take your time until
the jet loosens.
![Page 37: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/37.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove main jet – use tight
fitting screwdriver in slot
![Page 38: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/38.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Main jet
Pilot jet plug
Pilot jet
Pilot/main jets have number
identifiers engraved on them.
Comparing these numbers to those in
the factory Suzuki service manual is
recommended if the service history of
the bike is unknown.
![Page 39: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/39.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Insert main jet back into needle
jet w/o washer and then push
down using handle of
screwdriver. Jet comes out
from inside the carb throat.
![Page 40: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/40.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Needle jet removed
![Page 41: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/41.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Float pin has a nail-head
detail on one end and round
on the other
![Page 42: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/42.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Before removing the float pin we need to
support the float post with a small socket
positioned under nail head on pin.
5/32” socket or
similar (1/4”
drive)
![Page 43: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/43.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Gently tap the drift to remove
the pin. CAUTION: Do NOT use
a lot of force or the float post
will snap off.
![Page 44: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/44.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Float removed
Float needle
removed
![Page 45: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/45.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Use caution when
removing float seat to
assure brass seat is not
crushed
Inspect the float needle and seat
carefully. The spring on the
needle must be smooth and the
tip free of wear (if you feel a ridge
on the tapered portion of the
needle it needs to be replaced).
![Page 46: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/46.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove pilot air jet
![Page 47: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/47.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Keep parts from each carb
together (at least the float
needle and seat)
![Page 48: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/48.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
At this point the carbs are fully disassembled and need to be cleaned.
Load up your dip bucket and soak those parts! Do not soak the floats,
carb diaphragms or any other plastic parts.
If your carb dip is fresh and the carbs are not overly dirty, a couple of
hours dip time should suffice. For dirty carbs, and/or tired dip, it may take
as long as 24 hours. I recommend the shortest necessary dip time to
reduce expose of the throttle shaft seals from attack by the dip.
After dipping, rinse well in water. Hot water if you can get it, and consider
scrubbing the parts with an old toothbrush and soap as well.
Sometimes the carbs develop a white residue after drying so consider
spraying the carbs with WD-40, particularly if you don’t have compressed
air. Dry using compressed air if possible or just wait a while.
Last step is to use carb spray and shoot it though all the various passages
to make sure they are open. Pay attention to the choke pickup tube,
passage in the float bowl, and pilot jets. There are very small passages in
these parts that need to be verified as clean.
![Page 49: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/49.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
The factory black paint on these GS1150 carbs
won’t survive the dip process. I knew this would
happen so the paint was stripped before dipping
using paint stripper and mineral spirits.
![Page 50: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/50.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Spray in here6
Spray should come out here
![Page 51: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/51.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Spray comes out here
![Page 52: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/52.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Jet orifices must be
open.
Note how light
passes through jet
Note: these jets are not
adjustable and need to
be installed snuggly into
carb body.
![Page 53: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/53.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Grease/oil all O-rings before install
![Page 54: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/54.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Pay attention to
notch in needle jet
Carb reassembly is same as disassembly. The rest of this
tutorial is to highlight key assembly details.
![Page 55: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/55.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Float height for BS32 & BS34 carbs is 22.4 mm. The
BS36’s shown in this tutorial are to be set to 21.4 mm.
This line represents
the top of the carbs
gasket surface (no
gasket installed)
![Page 56: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/56.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Setting float height with calipers
![Page 57: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/57.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Float should just touch float needle,
but not compress spring. If weight of
float compress spring either hold up
float or replace needle
Measure float height
without gasket
![Page 58: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/58.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Forming the diaphragm in this
way makes it easier to keep the
lip in the groove on top of the
carbs while installing top cap.
Hold up slide with
finger then install cap
![Page 59: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/59.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Measuring fuel level using home made tool –
drill hole though old float bowl drain plug and
epoxy tube on top
![Page 60: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/60.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Feed fuel in until the
float stops the flow.
An elevated reservoir
is recommended
(works better than
bottle as shown)
![Page 61: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/61.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Set carb angle same as
on the bike. 1150 carbs
sit pretty much level.
![Page 62: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/62.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
This is a good way to make
sure your floats are sealing
and the fuel level is correct.
Adjust float tang as
necessary
![Page 63: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/63.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Remove needle from slide
using special C-clip pliers
Note: plastic spacer (see next slide)
This step is not necessary unless
your carbs run lean in the
midrange.
![Page 64: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/64.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Reducing the thickness of the
plastic spacer on top of the
needle clip results in a richer
mixture. Old plastic spacer
can be sanded down or
replaced with a washer stack
thinner than original spacer.
![Page 65: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/65.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Ready to gang carbs back together
Note: this bracket is in the
wrong position (oops) and
steel 1150 top covers have
been replaced with nifty
aluminum ones.
![Page 66: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/66.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Install fuel transfer tubes
and vent tube into outer
carb bodies (1 & 4), and
fuel inlet T-fitting
between 2 & 3
Join carbs together paying
attention to how throttle
sync components fit
together
Carb sync adjuster
![Page 67: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/67.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Join all carbs together
Note: hard to see but
fuel feed tube installed
![Page 68: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/68.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Install gang plates & screws
![Page 69: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/69.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Before installing choke rod take note of
proper orientation of depressions locking
the actuator forks.
Note orientation of rod
![Page 70: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/70.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Photo showing orientation of
choke spring and cable
attachment components
![Page 71: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/71.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
This different set of carbs demonstrates a different
choke actuation mechanism plus vent hoses w/T fittings
Different
type choke
linkage
Vacuum line to
petcock
![Page 72: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/72.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
This different set of carbs is shown to demonstrate
some common differences between BS Mikuni’s
Fuel inlet T
Vent hoses
Idle speed
adjustment knob
![Page 73: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/73.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Perform bench sync: all butterfly
valves should be open the same
amount. Using a piece of wire or
similar under the butterfly will
help judge sync.
#1#2
#3#4
First sync
2 – 3 together
adjusting here
2nd Sync
1 to 2
3rd Sync
4 to 3
Bench sync is good to
perform, but vacuum sync is
more important after engine
is running
![Page 74: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/74.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Use a piece of wire or similar
to judge if all the butterflys
are open the same amount.
![Page 75: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/75.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Loosen
locknut
Adjust sync with
screwdriver and then
hold screw while
tightening back
down locknut
![Page 76: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/76.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Adjust pilot screws by carefully screwing them in all the way until
bottomed, then open them back up, keeping track of how far you
turn them. 1 turn = 360 degrees. Set to 2 ½ turns open at first
and fine tune from there (as detailed on the following slide)
![Page 77: CV Carburetor Rebuild Tutorial - xs11.com.auxs11.com.au/Info/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf · Mikuni BS (CV) Carburetor Rebuild Tutorial Remove pilot jet plug (replace](https://reader033.vdocuments.us/reader033/viewer/2022052222/5f065f9d7e708231d417abed/html5/thumbnails/77.jpg)
Mikuni BS (CV) Carburetor Rebuild Tutorial
Congratulations on a job well done!!!
A few random notes6
•The bike will run very poorly, or not at all, without the airbox installed. The airbox also needs to
be properly sealed, so consider replacing any deteriorated foam seals as needed.
•If pod air filters are installed the carbs will have to be rejetted to match the low restriction
airflow. A header may also trigger the need to rejet, but not to the extent pods will. Dynojet kits
are a popular choice.
•Fine tune the carbs (engine fully warmed up and idling) by adjust the pilot screws in roughly
equal amounts until the highest idle speed is achieved. If the engine speed doesn’t respond to
this tweak, leave them at 2.5 turns.
•If the engine stumbles just off idle, try opening the pilot screws another ½ turn and try again.
The maximum number of open turns is four, otherwise you should get larger pilot jets.
•If the engine surges or feels like it’s running out of gas when cruising at steady speed, such as
on the freeway, opening the pilot screw more and/or shimming the needles may help
•Vacuum sync is critical. An erratic idle is often the result of poor sync
•If the idle speed increases significantly when the engine gets hot, or hangs and doesn’t drop
down quickly from higher rpm, there is likely a vacuum leak in the system or the pilot screws
are set too lean.