HSR Easy Kit Installation Instructions
 Revised 03/12/03
The HSR series carburetors are precise yet durable instruments; however, like any other piece of fine equipment, they
require correct installation and reasonable care to assure optimum performance and long life. Extra time spent during
installation will pay off in both short and long term performance and reliability.
This Mikuni HSR carburetor kit is designed to be a bolt-on application, and as such, is set-up and jetted properly for
most applications. However, since many Harley-Davidson motors are often highly modified, alternate tuning settings may
be required. The Mikuni HSR Tuning Manual helps make jetting alterations and adjustments an easy matter.
NOTE: Carburetor Kits not designated as C.A.R.B. exempt, are not legal for motor vehicles operated on public highways
f California, or in any other states and countries where similar laws apply.
in the state o
Notes, Cautions and Warnings
Statements in this manual preceded by these words are
very important:
Gives helpful information that can make a job easier.
Indicates a possibility of damage to the vehicle if instructions are
not followed. |
Indicates a possibility of personal injury or vehicle damage if
instructions are not followed.
Read these instructions carefully before you begin installa-
tion of your HSR kit. All procedures in this manual should
be followed, paying particular attention to the following:
1. Mikuni HSR series carburetors require the use of a
push/pull throttle assembly to assure closing of the throttle valve.
2. The throttle cables should be routed freely (without sharp bends)
between the throttle twist grip and the carburetor and
must not be pinched.
3. Gasoline is extremely flammable and is explosive under certain
conditions. Do not install your Mikuni near open flame.
4. Never look directly into the bore of the carburetor while the engine
is running as injury may result from possible backfire.
A moderate level of mechanical skill is required to install this
carburetor kit. After reading these instructions, if you have any
doubts, we recommend that you have a professional install it for
you. If you install the kit yourself, we recommend that you also
use the applicable shop manual for your motorcycle.
1. Disconnect the negative (-) battery terminal.
2. Turn the fuel petcock to the "OFF" position.
Elevate the rear of the fuel tank for better access. It is
not necessary to remove the tank to install this kit.
Remove the complete air cleaner assembly.
Disconnect the choke cable from its bracket.
Disconnect the vacuum and fuel hoses from the carb.
Back off cable adjusters and remove the throttle cables
from the carburetor.
. Remove the carburetor from the motorcycle.
9. Remove enrichener (choke) cable from the carburetor.
No oR
Control cables must not pull tight when handlebars are turned fo the
left and right fork stops. Also, be sure control cables and wires are
clear of the fork stops at the steering head so that they will not be
pinched when forks are turned against stops.
A. The HSR carburetor uses the stock throttle cables.
However, new cable routing is required to prevent cable
binding. To re-route the cables you must elevate the
rear of the tank. Cut the stock cable tie from the frame,
located above the front cylinder. Some models may use
sheet metal clips; if so, remove the cables from the clip.
Re-route the cables under the frame (Figure 1)..
= “= и A
Cut stock cable tie 7
> 7
Frame -
. И
Stock cable routing | y
py |
и и
и и
Re-route stock
throttle cables
under frame
Figure 1
B. Connect the throttle cables to the carburetor bell crank
by first installing the closing cable, then the opening
cable (Figure 2).
"Open" cable, adjust
for full throttle
“Close” cable,
- install first
ет =
N Vacuum fitting
for VO.E.S. or
Fuel Petcock
Figure 2
2. Carburetor Installation
A. Insert the carburetor into the stock Harley-Davidson
manifold. The carburetor will fit very snugly. Use grease
as a lubricant. Be sure that the choke routing doesn't
become kinked.
B. Slip the fuel hose onto the carburetor's fuel nipple and
secure with the enclosed hose clamp.
C. Some Twin Cam installations may require removal of a
small amount of fin material from the cylinders to clear
the float bowl.
1. Ifyou are not using the V.0. Е. S. or vacuum petcock, be sure
fo cap the vacuum fitting on the carburetor.
2. Before installing the carburetor, check the condition of the
carburetor seal; if damaged, it should be replaced to prevent
air leaks. We recommend that you start with a new seal.
. Stock Backplate (1340 Evo Only)
Assemble the Mikuni adapter (see Fig. 4). Attach the
adapter to the stock backplate using the provided
screws. The stock screws are too long.
B. Use a small amount of thread lock on each of the
screws (Figure 3).
C. Fully seat the carburetor into the manifold and center
it between the cylinders. Bolt the backplate to the
-Mikuni Cover
Stock Screw
Figure 3
. Screamin’ Eagle Backplate
A. Insert the enclosed large O-ring into the Mikuni
adapter. Assemble to the Screamin’ Eagle backplate.
Use thread lock on each of the stock bolts.
B. The remainder of the Mikuni/Screamin' Eagle instal
lation follows the Harley instructions. We recommend
that you follow those directions to complete the air
cleaner installation (Figure 4).
Cutaway of Adapter Ass'y
(Showing O-ring in position} 5
Mikuni H542
Screamin’ Eagle
Backplate ———
Figure 4
Cable Adjustment
5. Throttle
It is important to adjust the cable as described below to ensure
that the close cable operates correctly and can close the carbure-
tor fully.
A. Rotate the throttle grip to the full open position and
check to see that the throttle valve (slide) opens com-
pletely by looking into the carburetor bore. If the throttle
valve doesn't open fully, unscrew the adjuster on the
opening cable until it does. This adjustment should be
made carefully to get the maximum performance from
the carburetor. After the adjustment is made, tighten
the adjuster jam nut.
B. After adjusting the opening cable, turn the handlebars
to the right and adjust the throttle free-play with the
closing cable to approximately 1/8” (Figure 5).
Minimum Throttle Free Play
Figure 5
6. Cable Lube
Remove upper throttle housing and inject cable lube in
each cable (Figure 6).
Figure 6
7. Hose Routing
Route the carburetor overflow hose behind the rear push
rod tubes and between the crankcase and transmission. Do
not connect to any other hose.
1. If you are not using the V.O.E.S., seal the Vacuum Fitting on
the carburetor.
2. The Vent Fitting located above the Fuel Fitting must not be
sealed! Sealing it results in erratic air/fuel mixture ratios, poor
performance and possible engine damage.
3. You may have some remaining hoses. Since this is a perfor -
mance application only, any remaining hoses and related
hardware can be removed, as they are not required.
8. Choke Cable Installation
HSR series carburetors use either of two choke cables:
the stock Harley-Davidson cable (1990 and later) or the
Mikuni cable. The Mikuni cable is furnished for installations
that do not have a Harley Choke cable.
Follow these steps to install the choke cable:
1. Remove the stock Harley choke cable assembly.
2. Remove the spring and plunger from the stock cable.
3. Remove the Mikuni “Starter Nut” from the HSR.
4. Remove the Mikuni spring and plunger from the HSR.
5. Install the Mikuni spring and plunger on the Harley cable.
6. Install the Harley choke cable with the fitted Mikuni
spring and plunger into the HSR carburetor.
DO NOT use the Mikuni Starter Nut; discard it.
DO NOT use the Harley spring or plunger; discard them.
Note: If you do not have installation instructions, you may
download them from the “www.mikuni.com” website in the
“manuals” section.
If the Mikuni Starter Nut is fitted to the Harley cable, the
choke plunger is held off its seat and the choke is open all
the time. If the Harley spring and plunger are used, the
plunger does not seal and the choke is open all the time.
The result, in both cases, is very poor fuel mileage (30 mpg
or less).
Another possible cause of poor mileage, rough idle and
fouled spark plugs is incorrect cable routing. The stock
Harley choke cable is very stiff and may not be fully seated
in the metal elbow at the carburetor end.
Harley's choke knob has the word “CHOKE” in white. The
Mikuni knob has a small brass bump in its center.
The Mikuni spring is longer and stiffer than Harley's.
The Mikuni nut has a smaller hole where the cable fits and
must not be used with the Harley choke cable.
The Harley nutis larger and is serrated around it s edge.
The Mikuni “Starter Plunger” and the Harley plunger are
different and must not be interchanged. While they are very
similar and both slide into the HSR carburetor, the Harley
plunger does not work in the HSR The Harley plunger
does not seal and causes a severe rich condition.
The Mikuni choke cable has an adjuster; the Harley cable
does not. The Mikuni threaded section is steel; Harley's is
plastic. The Mikuni cable has a hold-open detent; Harley's
has a friction adjuster. The Mikuni knob has a small brass
center while Harley's has the word “CHOKE” in white.
The Harley cable end may not completely bottom in the
socket formed in the metal elbow. If the cable is not bot
tomed, the starter plunger does not seal. Poor mileage and
a rich idle results. |
The fix is to re-route the cable so that it can bottom. A
simple 'wiggle' may be enough to get the cable seated.
There must be some free play in the choke cable to
ensure that the choke plunger is bottoming (sealing). Any
amount of free play is okay, but there must be some.
H-D: Check free play by slightly loosening the friction nut.
Then, slide the knob in and out to check free play.
Mikuni: If there is no free play, use the adjuster under the
rubber boot near the carburetor.
Mikuni's cable adjuster is covered by a rubber boot.
There must be some free play in the cable. Any amount
will do but there must be some to ensure that the choke
plunger is fully bottomed.
. Startin
Re-connect the battery at this time and re-assemble
the remainder of the motorcycle.
Turn the fuel petcock on and start the motorcycle as
you normally would.
After the engine is warmed up adjust the idle to the
recommended idle speed of 1,000 to 1,100 rpm.
о п DIO
'95 to present models are equipped with a vacuum petcock. It may
be necessary to crank the engine over several times before fuel
flows to the carburetor.
See the enclosed “HSR Tuning Manual” for fine-tuning
instructions. This manual can also be printed from our
website at: www.mikuni.com.
Parts List for 42-7 and 42-18
Pa escription ty HSR Kit
TM42-6 Carburetor 1 7,18
HS42/001 Adapter 1 7,18
HS42/002 Screw, Adapter 3 7
HS42/003 O-ring (Large) 1 7,18
HS42/006 Cover, Cleaner 1 7
Z70/073 Cable Lube 1 7, 18
N100.604-165 Main Jet 1 7,18
VM28/486-20 Pilot Jet 1 18
TM42/11-50 Pump Nozzle 1 18
N124.063 O-Ring 1 18
270/045 Hose Clamp 1 7,18
Z70/146 Cable Tie 3 7,18
Twin Cam Optional Tuning
Suggestion: Certain Twin Cam 88/95 ci configurations
may improve mileage by using our #20 pilot jet, #50 a/p
nozzle and #2 needle clip position. These parts are now
included. Refer to the HSR Tuning Manual (pg. 8-9) for
detailed instructions.
. TM42/47
J8-8CFY 02-97
. 925-98006
| 616-94029
‚ TM42/46
. TM42/19
‚ TM42/15
Screw, Top Cover
Screw, Top Cover
Top Cover, (42/45)
Top Cover, (HSR 48)
Gasket, Top Cover
E-Ring, Jet Needle
Washer, Jet Needle
Jet Needle (42)
Jet Needle (45/48)
Lever, T.V. (42/45)
Lever, T.V. (48)
E-Ring, Link Lever
Packing, Link Lever
Pin, Link Lever
Throttle Valve (Slide)
Screw, Needle Retainer
Clip, Needle Retainer
Sealing Ring, T.V. (42/45)
Sealing Ring, T.V. (48)
Seal, Throttle Valve
Pulley, Cable Bracket
E-Ring, Cable Bracket
Bracket Ass’y, Cable
Bracket Ass y, Sportster
Bolt, Bracket
Spacer, Bracket
Plate, Lock Tab
Starter Nut, Choke
Spring, Starter Plunger
Seal, Spigot Body
Ring (Steel)
Lever, A/P
Pin, Throttle Lever
Lever, Throttle
Spring, A/P
Screw, A/P
g, A/P
A AAN kf A LE essere ms emma
fal as rt
ng, Shaft (Plastic)
Adjusting Screw, A/P
O-Ring, A/P Screw
Plate, Lock Tab for Shaft
Pin, Return Lever
Lever, Return
Adjusting Screw, Throttle
Nut, Throttle Stop
Spring, Throttle Return
Shaft, Throttle
Plate, Fue! Joint Retainer
Screw, Fuel Joint
Screw, Pilot Air
50. N133.206 Spring, Pilot Air
51. VM12/205 Washer, Pilot Air
52. N133.037 O-Ring, Pilot Air
53. TM40/27 Fuel Joint |
54. KV/10 O-Ring, Fuel Joint
55. B30/398 Packing, idle Adjuster
Washer, Idle Adjuster —
Spring, idie Adjuster
Ring, ldle Adjuster
56. VM22/138
57. 730-09018
58. 925-15001
59. TM42/32 Idle Adjuster (Long)
5%a. 990-605-065 Idle Adjuster (Short)
60. BS30/97-00 Air Jet (Blank)
61. 784-430000-Y-6 Needle Jet (723)
62. TM42/11-70 Nozzle, Accel. Pump
63. N124.063 O-Ring, A/P
64. VM28/486-25 Pilot Jet
65. TM42/12 Extender, Main Jet (42/45)
65a. TM42/12-1A Extender, Main Jet (48)
66. N100.604-160 Main Jet
67. 6716-33003 O-Ring N.V.
68. VM13/216 Screw, N.V. Retainer
69. 786-27001-4.2 Needle Valve Ass'y (42/45)
69a. 786-27002-1A Needle Valve Ass’y (48)
70. 859-32027 Float Ass’y
71. BV26/22 Pin, Float
72. C2=0410 Screw, Float Pin
73. 6716-94028 Packing, Float Bowl
74. TM42/05 Float, Chamber Body
15. N122.028 Hose, Overflow
76. VM28/254 … O-Ring, Drain Plug
77. TM32/41 Drain plug (42/45)
77a. TM32/41-1D Drain Plug (48)
78. C2=0412-B Screw, Flt Bowl, short
79. TM36/44-1A Rod, A/P
80. TM36/64 Boot, A/P Rod
81. TM36/60 Plunger, A/P
82. VM14SC13/89 Spring, A/P
83. N198.063 Rubber Cap, Purge Port
Alternate Parts
Jet Needles:
HSR42 HSR45/48
J8-BDDY01-95 J8-8CFY02-95 Richer
J8-8DDY01-96 J8-8CFY02-96 Richer
J8-8DDY01-97 J8-8CFY02-97 Std
J8-8DDY01-98 J8-8CFY02-98 Leaner
Accelerator Pump Nozzles:
TM42/11-70 Std
TM42/11-60 Leaner
TM42/11-50 Leaner
Needle Valve Assemblies:
786-27002-1A-4.5 Std (HSR48)
786-27001-4.2 Std (HSR42/45)
786-27001-3.5 Smaller NOTE:
786-27001-2.3 Pressure only. 1. Hned-through-part
numbers are not
2. Parts in bold are
included in rebuild
Rebuild Kit:
HSR42/45: KHS-016
HSR48: KHS-031
— 80
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF