Mikuni TMX 35 User manual

TNOUBLESHOUIilO AUIDE
Outlined belorv are the proper prccedures br diagnosis and conection of
operating problems rclated to )@ur Mikuni TMX Series Carlcuretor
CHECK FOR:
WERFIOW
'1. Worn inlet valve or dirty inlet valve seat.
2. lmproperluel le\€l in lloat bor{|.
3. Damaged float bovl o{ing gaslct.
4. Loose float bor{|.
POOR IDLIl{G
1. ldle speed improperly adlusted.
2. Clogged bypass.
3. Clogged pilot iet.
4. Loose pilotjet.
5. Air leaking into system.
POOR ACCELERAIION
1. Clogged pilotiel.
2. Fuel level too loil.
HARO STARTII{G
1. Choke not operatino properly.
2. Generälly djrty carburelor
3. Loose carburetor hose clamp.
4. Fuel ffirflw.
POOR PERFORi'AI{CE
'1. ldle sp€ed improperly adiusted.
2. Fuel overflw
3. Main iet loosened.
4. Air leak in intake system.
5. 0irty or clogged carburetor or air cleanei:
POOR HIGH SPEED PERFORMAI{CE
1. Loose main iet.
2. lmpmper fuel le14l in float chambff
3. Dirt lodged in strainerin fuel tank
4. Clogged main jet.
ABN0RitAL C0M8USIt0l{ (FUEL MTXTURE)
1. Genenlly dirty carburetor
2. Dirty orclogged tuel line.
3. Air leakng into system.
Loss 0F P0WER (LEAi{)
1. Clogged luel line.
2. Dirtyfuel tank.
3. Air leaking into system.
4. Clogged fuel filter in luel tank.
5 Genenlly dirty carburetor
toss 0F P0WER (RrcHl
'1. Dirty air cleaner element.
2. Throttle cable notworking.
3. Correct ietting lor change 0t altitude operation.
4. Loose jets.
REMEDY:
'1. Replace val\€ or clean valve seat.
2. Adjust floattabs for correcl luel lewl.
3. Relace o-ring
4. Tighten.
'1. Adiust idle speeds.
2. Clean.
3. Clean iet.
4. Tighten tet.
5 Tighten manilold and/or hose clamps.
1. Clean.
2. Mjust le1ßl of float assembly.
1. Clean orreplacaplungeii
2. Disassemble and clean.
3. Tighten.
4. lnspect lloat assembly and inlet ulw end adjust
or replace.
'1. Adiust idle.
2. lnsped float assembly and inlet nh€ and adiust
or replace.
3. lnspect main iet and tighten.
4. Tighten manilold and/or hose clamps.
5. Clean.
1. lnsped main iet and üOhten.
2. Mjust{loat assembly for correcl fuel level.
3. Clean straine[
4. Clean.
1. Disassemble and clean.
2. Clean fuel line or replace.
3. Check mOuntir{.qüts or hose clamps l0r tightness.
1. Clean.
2. Clean. :
3. Check mounting nuts or hose cllnps I0r tightness.
4. Clean fuel filter
5. Disassemble and clean.
1. Clean or replace air cleaner element.
2. Check throttle cable and adjust or replace.
3. See tuning.
4. Tighten jets.
r$
lit:
!i;l
MIKUNI AMERICAN CORPORATION
Motorcycle Carbu retor Division
8910 Mikuni Averiue, Northridge, CA 91324-3496 USA

WTNODUCTIOIT
MIKUITI TMXSEß'ES NACINE CANBUNEMN
jet can easily be accomplished by unscrewing the float bowl drain plug.
A new float valve system with independently moving floats, working in con-
junction with the main jet enclosed in a new baffle chamber allows the TMX
Carburetor to perform smoothly without hesitation across the roughest ter-
rain and under the most extreme lean angles and cornering forces.
Congratulations on your selection of the Mikuni TMX Carburetor for your
particular high performance application. We are positive you will be ex-
tremely satisfied with the performance gains and tuning ease we designed
it to provide.
ALWAYS RIDE WITH CARE AND SAFETY BOTH ON AND OFF THE
RACE TRACK. Never ride without a helmet, eye protection, and proper
protective clothing. Mikuni TMX Series Carburetors are legal in California
ONLY FOR RACING VEHICLES WHICH MAY NEVER BE USED UPON A
PUBLIC SIREET OR HIGHWAY. ln other states check for similar laws
which may apply.
MIKUNI AMERICAN CORPORATION
Motorcycle Carburetor Division
8910 Mikuni Avenue, Northridge, CA 91324€496 USA
With its intoduction the Mikuni TMX Series Racing Carburetor signified a
new generation of high performance carburetion from Mikuni designed
particularly for 2-shoke engines in motocross, off-road bike and AW racing
applications. The TMX Series will also perform extremely well in other ap
plications including llat track and road racing. For 4-stroke engine racing
applications the TMX Series will also provide a significant performance im-
provemgnt over stock carburelion systems although Mikuni recommends
use of the RS Series Carburetors which were designed particularly for 4-
stroke application.
An all new design, the Mikuni TMX Carburetor features a radial flat slide
design working in a smooth bore venturi that establishes a new perform-
ance standard for improved throttle response, along with a wider and
stronger overall powerband from the engine. These performance gains are
provided by the radial flat slide throttle valve design which produces a 400/o
greater boost signal lrom the air flowing past it for better throttle response
and an increased sensitivity to tuning. Very minimum tuning changes are
able to produce noticeable results in engine performance.
The TMXCarburetoris designed with a new lightweightand more compact
body design with easy maintenance and tuning features. The carburetor's
jet needle position may be changed easily and quickly. Access to the main
2

ITISTAL''//TION
EENENAL "IIST
NUCT IO NS
Belore you begin the installation of your Mikuni carburetor, take the time to
read these instructions thoroughly.
WARNING: Gasoline is extremely flammable and can be explosive under
certain conditions. Do not smoke. Make sure your work area is well venti-
lated and free from any source ol llame or spark. This includes any appli-
ance with a pilot light (i.e. a water heater in a garage).
IMPORIANT Never remove a spark plug lead wire or fuel line while a mo-
tor is running as this can result in a fire or explosion.
CHECK THROTTLE GABLE:
lnstallation of your aftermarkel fMX Carburetor may require changing the
stockthrottle cable assembly's innercable. To determine if yourstock inner
cable is the correct length, disconnect and remove the throttle cable from
the carburetor. Check the inner cable's free length with the throttle control
completely closed and the cable adjuster turned in all the way. Check the
inner cable's free length against the drawing. lf your inner cable does not
have a lree length between 86mm - 90mm, follow the next step to con-
struct a new inner cable.
86mm-90mm
1). Cut your stock inner cable so it can be removed from the outer
casing. Note: Do not damage outer casing, but simply slide inner
cable out.
2). Attach new inner cable supplied with your new TMX carburetor to the
throttle drum and slide the new inner cable into th€ outer casing. Set
the cable adjuster as shown in diagram B). then follow the instruc-
tions in diagram C). for cutting and soldering the inner cable.
il fl+ff$.*,
ü
c). I tt--l
.",u ll I
. Hj"-fl 1,,u"
ll I ",,'",""".
rll
A_r
I/Slide Cable End Flush
_,y' With TipOilnnor Cabte
lll fl And soidor
il
ll
II
il
ö
t
I.\
IV flÜ Excess Solder
3). Attach the throttle cable assembly to the TMX Carburetor.
4). Attach the air lilter boot adapter to the carburetor as shown in D).
5). lnstall the carburetor into the intake manifold and attach the air filter
bootto adapter.
o). Air Bd Adaplor
,18
lmml
H
n-it
tlt
Zcrtfo, t98zg
6). IMPOFrrANT lnstall fuel hose from fuel tank petcock to carburetor
using hose clamps. Use Yro" to 1/+" hose reducer if needed. lf fuel
hose is hard or cracked, replace it with new hose. TURN FUEL ON
AND CHECK FOR LEAKS.
4. Adjust the throttle cable to manufacturer's specifications. CAUTION:
Be sure the throttle operates smoothly and the carburetor throtile
slide returns to its idle position when the handlebars are turned from
lock to lock, and that the throttle cable does not pinch or bind when
the handlebars are turned. 5
3mm
B).

1q
3tc
112
It
Pilot Jet
& Pilot
AirScrew lI
FUEL METERING CIRCUITS
PILOT SYSTEM The Pilot System is comprised of two adjustable
components:
PILOI AR SCREW when turned in, richens the fuel mixture by reduc-
ing the air flow into the Pilot System which operates from idle to approxi-
mately 1/4th open throttle. The effective adjustment range of the Pilot Air
Screw is between 1ä to 2 turns out. lf the Pilot Air Screw needs to be set
more than 2 turns out to achieve the best idle, the next smaller size Pilot Jet
is required. lf less than 1ä turn is required, then a larger Pilot Jet should be
used. The Pilot Air Screw should be adjusted to provide the highest engine
RPM while the engine is at idle.
PILOr JET is the component supplying the majority of fuel from idle to
1/ath throttle position. The typical jet size should fall between No. 15 and
No.30. For selecting the correct Pilot Jet at idle, read the previous tuning
directions tor the Pilol Air Screw. ll the engine appears to run too lean or too
rich off of idle, the carburetcir may require a size smaller or larger Pilot Jet
and/or the Pilot Air Screw may require adjustment.
7
Jet Needle &
Clip Position
Throttle Valve
Cutaway
6
Main Jet

JET NEEDLE The Jet Needle is the tapered rod that is positioned in the
throttle valve by the 'E'-Clip. The taper of the needle increases the clear-
ance between the Jet Needle and the fixed Needle Jet outlet as the throttle
is opened. As the air flow volume increases past the throttle slide, the fuel
volume is also increased to maintain the correct airlluel ratio.
'E'-Clip Position
Leaner
-T--
'E'Taper
__L
I
'J'Taper
6EJ12-57 Leaner
6EJ12-56 ^
TMXss 6EJ12-s5 I
6EJ12-s4 .t
6EJ12-53 Richer
NEEDLE'ELCLIP POSITION The
position of the 'E'-Clip in the Jet
Needle is used to correct or change
the airlfuel ratio between l+th and
%th throttle valve position. The'E'-
Clipcan be raised or lowered onthe
Jet Needle. To richen the fuel mix-
ture the 'E'-Clip is lowered on the
Jet Needle, raising the Jet Needle s
position in the throttle slide. To lean
the fuel mixture the 'E'-Clip is
raised on the Jel Needle, lowering
the Jet Needle's position in the
throüle slide.
OPTIONAL JET NEEDLES To cor-
rect the fuel mixture at lÄth to l/+th
throttle slide position it may be nec-
essary to change the Jet Needle.
The Jet Needle will have a series of
numbers stamped on it.
Example: 6EJ12-55. The numbers
55 indicate that the outside diame-
ter (O.D.) of the Jet Needle is
2.55mm. The smaller the O.D. the
richer the mixture. The larger the
number the leaner the mixture.
Typical Jet Needles Available:
6EN11-54
TMX35 6EN11-53
6EN11-52
o.D.
Straight Portion
11
2l
3l
4l
5v
Richer
THROTTLE VALVE The Throttle Valve cutaway affects engine/carburetor
response between lrbth tol/ath throttle slide position. The smaller lhe slide
numberi the richer the mixture. Available range 3.0, 3.5, 4.0, 5.0, 6.0 (richer
- leaner).
MAIN JET The Main Jet is located in the float bowl and can be removed or
changed through the float bowl drain plug hole. The Main Jet controls the
air/fuel mixture ratio from q+ths to wide open thottle position. The larger
the number stamped on the Main Jet the richer the mildure.
When tuning the TMX Carburetor the tuning components being used are
relative to the throttle slide position, not engine RPM or actual vehicle
speed. Most tuning can be accomplished at relatively low speeds by mak-
ing note ol the approximate throttle position at which there appears lo be a
tuning problem. Make tuning adjustments by adiusting or changing the
tuning component controlling the fuel mixture al that throttle slide position.
FLOAT LEVEL ADJUSTMENT
lnvert carburetor and remove float bowl.
The Float Assembly's actuator tab should just begin contact with the Nee
dle Valve Assembly when the bottom of the Float Assembly is 20mmfrom
carburetor bottom as shown. Make required adjustments by bending actu-
ator tab.
Leaner
t
Richer
8
ActuatorTab

TMXSEHES/flMX 35 and 38
MIKUNITMX SERIES PAMS LIST
No. De$dplion
1 MIXING AOry CARA
2 JET NEEDLE
3 COr'ER, CARB TOP
4 LOCKNUT, ADJUSTER
5 CAP RUBBER
6 ADJUSER. CABLE
7 O-RING. rcPCOVEF
8 E.RING, NEEDLECLIP
9 FING, AETAINING
1O AOJUSTEFI, IDLE STOP
11 SPRING. IDLE ADJUST
12 PLUNGER. SIAMERASBY
13 SCREW AIR ANUSTEF
14 SPRING, AIRSÖREW
15 CHAMAER. FLOAT BtrL
16 VALVE SEAT, NEEDLE
17 PILOTJff
1A MAINJET
19 ARM. FLOAT
rc NEEOLE VALVEASEMALY
21 PIN.FLOATARM
22 GRING. NEEOLE VALVE
8 CAE FLOAT RflAINER
24 SCREWTOPCOVEF
25 THROfrLE VALVE
S SPRING, TV
27 HO6E. VENf
28 SCREW. FLüT BO/VL
ä HOSE, Or'ER FLCIil
S FLOAI LEFT SIDE
31 GRINg. DFAIN PLUG
32 DRAIN PLUO
33 FLOAT, RIGHTSIOE
A GASKEI, FLOAT BO\A/L
PAtrNUMBEB€O€S}=
NO AVAILABLE STOCK
ss€eF
J8-SEETUNING
77619014
B30t247
vMut2a2
VMOTT
61&9m
BSg126
TMS/g
m+25008
N110m
lMgm
60336002
TMgß
8m.260023.5
vM2Z210
4M2
VMß15
7&26m5
vMmßr5
&10
vM2d42
cw2-ßr2
ß241n2
7S1S19
8&24011
cw2{308
w2m22
8595m21
vM2&29
TMß{
TMX CARB PAM NUMBERS
AORE
SIZE
TM35-1 35mm
TM&27 38mh
TM$-18 38mm
I'QJ
rt l2-"
\/)
ll--
'--+=,1 t\,,1
/\lnl
HIIl!,,
U G\ll
SPIGtr
OD
40mm
/-r
g
'-Üfi_"
"€ E..s
a_.
_eq\
lltLj
,^^\
,x=5\
il
\ll
\\ ri
_, ]\ I
t) [
// ,@
/,8
/E
' ,"_-tb
!€
f\@
ts
859-520m
TM38/52
"k\=-,'
TL.,,
t9
IJ-'"
\
10
MIKAM TCCESSOf,'ES
ORDERING INFORMATION
All Mikuni accessories are available from your local motorcycle parts
dealeri Mikuni distributor, or direct by mail from Mikuni American. No
phone orders, please. Mail your order with certified check, money order,
VISA or MASTERCARD information. California residents include 61ho/oCA
sales tax.
MIKUNI POCKET TUNER
A handy pocket size slide calcula-
tor which can be used to determine
required jetting changes in Mikuni
carburetors due to changes in am-
bient temperature, altitude, or both.
The Pocket Tuner is applicable to
both single and multi-carburetor
applications on two-stroke and
four-stroke engines. lt also comes
with a guide lor determining rich or
lean carburetor conditions.
MIKUNI POCKETTURNER
Part No. MK-SSGTNR $2.95
MIKUNI RACETEAM
APPAREL
MIKUNIT-SHIRI SILVER
S, M, LG, XLG, $9.95
Part No. MK4C/-3
MIKUNI T.SHIRT, TURQUOISE
S, M, LG, XLG,
Part No. MK-407.4 $9.95
MIKUNI KNIT SPOHT SHIRT
SILVER, S, M, LG, XLG,
Part No. MK407€ $17.95
MIKUNI VENTED CAP
SILVER, ONE SIZE,
Part No. MK4O8-3 $5.95
MIKUNI CORDUROTCAP
SILVER, ONE SIZE,
Part No. MK-4O&7$12.95
MIKUNI DAYTONA TEAM JACKET
SILVER, S, M, LG, XLG,
Part No. MK-52G7 $49.95
MIKUNI DECAL KIT
ASSORTMENTOF 1Z
Part No. MK-5o2-ASrMT $9.95
MIKUNI EMBLEM PArcH
RED/wH|TABLUE,
Part No. MK-50$1 $2.00