To Kramer - Inchpincher · Keihin Fcr Carb Tech Fcr Body Cleaning The Keihin FCR Carb Rebuild With Zip-Ty Racing - Dr. Dirt 01 Ty Davis starts by thoroughly cleaning the FCR body

04

.05

.10

07

:28

The K

eihin FCR

Carb

Reb

uild W

ith Zip-T

y Racing - D

r. Dirt - D

irt Rid

er Magazine

Seite 1 von 3

http://w

ww

.dirtrid

er.com/tech/1

41

_07

07

_keihin_fcr_carb_reb

uild/ind

ex.html

Ho

me

»Tech

»Th

e K

eih

in FC

R C

arb

Reb

uild

With

Zip

-Ty

Racin

g - D

r. Dirt

Th

e K

eih

in FC

R C

arb

Reb

uild

With

Zip

-Ty

Racin

g - D

r. Dirt

Bik

e: P

erfo

rman

ce Fo

ur-S

trokes

From the July, 2007 issue of D

irt Rider

By K

arel Kram

erPhotography by K

arel Kram

er

Tech

Ho

w-T

oA

good portion of m

odern four-stroke engine

performance

is due to

the Keihin

FCR

carburetor.An accelerator pum

p and

a high-tech

slidesupported

by four wheels m

ake the FC

R a

relatively complex

design. There are many parts

that can w

ear out and get dirty or gum

med

up.There are a

few shops that specialize in m

odsand

service for these carburetors. S

ome, such

asJD

Jetting (w

ww

.jdjetting.com; 253.939.7114)

and Factory Pro (w

ww

.factorypro.com;

800.869.0497), sell kits that you install yourself, and others, such

as Zip-

Ty Racing

(ww

w.ziptyracing.com

; 760.244.7028) and Tokyom

ods(w

ww

.tokyomods.com

; 888.457.9403), will set up

the carburetor for youor actually m

odify it for increased

performance

and response. W

hiteBrothers offers both

options.

As com

plex as the FC

R carburetor is, it is m

oreintim

idating to

look at than it is to

work on. You

will still need

a good

manual.

Getting

the carburetor off and back

on will be the

hardest part. You'll need to

remove the cover on

the side of the carburetor, disconnect the throttle

cables, make

sure the vent hoses are all free from

the bike and

disconnect the wire to

the TPS. D

o not remove the TPS

from the

carburetor; it is synched to

the throttle shaft with

a m

eter, and it m

ust beresynched if rem

oved. With

perimeter-fram

e machines, it is alm

ost always

easier to take

off the subframe and

the shock before removing the

carburetor.

Rela

ted

Ph

oto

s

Rela

ted

Article

s

Zip

-Ty R

acin

g B

illet A

ir Scre

wM

odern tw

o-stroke m

otocross and off-road

bikes seem to

come jetted

far better than everbefore. The... m

ore

Zip

-Ty R

acin

g X

F+ W

ate

rless R

ace

Co

ola

nt

Avoid

all the hassles of traditional water-based

coolants, from m

etal-jacket oxidation to... m

ore

Th

e T

ortu

re T

est - Z

ip-T

y Racin

gH

usq

varn

a T

XC

45

0

04.05.10 07:29Keihin Fcr Carb Tech Carburetor Photo

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Keihin Fcr Carb Tech Carburetor

The Keihin FCR Carb Rebuild With Zip-Ty Racing - Dr. Dirt

View Related Article

04.05.10 07:31Keihin Fcr Carb Tech Fcr Body Cleaning Photo



Keihin Fcr Carb Tech Fcr Body Cleaning


01 Ty Davis starts by thoroughly cleaning the FCR body in a solvent tank filled with Simple Green rather than using apetroleum-based solvent or contact cleaner. He warns that you should never spray contact cleaner into the mouth of acarb. View Related Article

04.05.10 07:35Keihin Fcr Carb Tech Fuel Screw Photo



Keihin Fcr Carb Tech Fuel Screw


02 If you have an aftermarket fuel screw installed, this is a good time to remove it. Take care so you don't lose the smallspring, washer or O-ring. If you still have the stock fuel screw, removing it can wait. View Related Article

04.05.10 07:36Keihin Fcr Carb Tech Remove Bolt Photo



Keihin Fcr Carb Tech Remove Bolt


03 You will need to extract this bolt from the throttle linkage above the slide. It may be a secure Torx with a tiny post inthe middle. You may need to visit a special tool store to find a dimpled Torx socket. View Related Article

04.05.10 07:37Keihin Fcr Carb Tech Torx Removed Photo


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Keihin Fcr Carb Tech Torx Removed


04 With the Torx removed, the slide's lifting arm can rotate out of the way, and the slide can be pulled out. The brassfitting on top of the slide holds the needle in place. View Related Article

04.05.10 07:38Keihin Fcr Carb Tech Replacing Wear Plate Photo


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Keihin Fcr Carb Tech Replacing Wear Plate


05 The slide has a wear plate that lifts off. Some companies recommend changing it every 25 hours. It is an expensivepart, but replacing it can make a big difference in how crisply and cleanly the bike runs down low. View Related Article

04.05.10 07:39Keihin Fcr Carb Tech Replace Seal Photo



Keihin Fcr Carb Tech Replace Seal


06 The back side of the wear plate has this very delicate seal. Davis warns that chemicals like contact cleaner will causethe seal to swell and ruin it. It is a good idea to replace the seal when the carb is apart. View Related Article

04.05.10 07:41Keihin Fcr Carb Tech Remove Bowl Screws Photo



Keihin Fcr Carb Tech Remove Bowl Screws


07 Davis removes all the vent hoses at this point. Small brackets mounted on each rear corner of the float bowl guidesome of the vent hoses. Remove the bowl screws and the idle adjustment bracket. View Related Article

04.05.10 07:42Keihin Fcr Carb Tech Float Bowl Photo



Keihin Fcr Carb Tech Float Bowl


08 Work off the float bowl and look for any dirt or other junk in the bowl. This one is quite clean. Most water andsediment will settle in the drain bolt. View Related Article

04.05.10 07:44Keihin Fcr Carb Tech Throttle Pivot Shaft Photo



Keihin Fcr Carb Tech Throttle Pivot Shaft


09 With the bolt removed, the throttle pivot shaft should simply pull out. Note the return spring attachment and theplacement of the two washers. Clean up the shaft and assorted parts. Set these parts safely aside. View Related Article

04.05.10 07:46Keihin Fcr Carb Tech Needle Photo



Keihin Fcr Carb Tech Needle


10 At the top of the slide will be some arrangement that allows removal of the needle. Some off-road bikes havenonadjustable needles (only one clip position), and they can be replaced with an adjustable one for tuning. View RelatedArticle

04.05.10 07:48Keihin Fcr Carb Tech Float Pin Photo



Keihin Fcr Carb Tech Float Pin


11 Using a small tool, push out the float pin. A small Allen wrench or the back end of a drill bit should work fine. Once thepin is moved, you should be able to pull it out with your fingers. View Related Article

04.05.10 07:49Keihin Fcr Carb Tech Float Needle Photo



Keihin Fcr Carb Tech Float Needle


12 The float manipulates this float needle to keep the fuel level in the float bowl constant. Look for damage near thepointed rubber tip. The needle is loosely attached to the float via the wire loop. Don't lose it. View Related Article

04.05.10 07:49Keihin Fcr Carb Tech Needle Jet Photo



Keihin Fcr Carb Tech Needle Jet


13 The main jet is threaded into the needle jet, so remove them together. The fuel baffle (called a "spacer" in themanual) will come off easily after the needle jet tube is out. View Related Article

04.05.10 07:50Keihin Fcr Carb Tech Unscrew Starter Jet And Pilot Jet Photo



Keihin Fcr Carb Tech Unscrew Starter Jet And Pilot Jet


14 Unscrew the starter jet and the pilot jet. A blade screwdriver with a tip or shaft larger than 4mm wide will jam in thepilot-jet opening. Clean all the jets, and ensure that all of the openings are unrestricted. View Related Article

04.05.10 09:25Keihin Fcr Carb Tech Screen Photo



Keihin Fcr Carb Tech Screen


15 There is a screen at the bottom of the needle-valve seat that prevents trash in the fuel from entering the float bowl. Itcannot be removed for cleaning, so use compressed air to blow it clean from this side. View Related Article

04.05.10 09:25Keihin Fcr Carb Tech Accelerator Pump Rod Photo



Keihin Fcr Carb Tech Accelerator Pump Rod


16 Use a finger to operate the accelerator-pump rod through a full stroke. You should feel spring resistance but no hardspots or hitches in the travel. If it doesn't move freely, pull it apart and clean it. View Related Article

04.05.10 09:26Keihin Fcr Carb Tech Greased O Rings Photo



Keihin Fcr Carb Tech Greased O Rings


17 A small screw holds the fuel-line fitting in place. The carburetor was otherwise quite clean, but this fitting and passageneed a bath. View Related Article

04.05.10 09:27Keihin Fcr Carb Tech Needle Bearings Photo



Keihin Fcr Carb Tech Needle Bearings


18 A little grease on the O-rings will ease the cleaned fitting back into the carburetor body. Don't get carried away withthe grease. Install the screw that holds the fuel-line fitting. It shouldn't need thread-locker. View Related Article

04.05.10 09:29Keihin Fcr Carb Tech Needle Bearings Photo



Keihin Fcr Carb Tech Needle Bearings


19 The throttle shaft rides on two small needle bearings, and they should get a little grease before the shaft is installed. Acotton swab is a good tool for this job. View Related Article

04.05.10 09:35Keihin Fcr Carb Tech Engage Hook Photo



Keihin Fcr Carb Tech Engage Hook


20 The throttle-return spring has a hook that must engage the throttle shaft before the shaft is reinserted. The shaftwashers fit between the body and the throttle-valve lever: the metal one against the carburetor body and the resinwasher against the lever. View Related Article

04.05.10 09:41Keihin Fcr Carb Tech Lined Up Photo



Keihin Fcr Carb Tech Lined Up


21 Getting all the throttle-valve parts lined up takes a bit of fiddling, but once they are arranged, the throttle shaft shouldeasily slip through the freshly greased bearings. View Related Article

04.05.10 09:42Keihin Fcr Carb Tech Place Main Jet Combo Into Body Photo



Keihin Fcr Carb Tech Place Main Jet Combo Into Body


22 After setting the plastic spacer in place, use a socket to thread the needle jet/main jet combo into the body. The pilotand starter jets go in next. The threads are brass inside aluminum, so don't go crazy tightening jets. View Related Article

04.05.10 09:42Keihin Fcr Carb Tech Wire Loop Photo



Keihin Fcr Carb Tech Wire Loop


23 Before the float and needle valve go in, this wire loop attached to the needle must be slipped over this tang on thefloat. Work over a surface that will allow you to find the float needle if it is dropped. View Related Article

04.05.10 09:42Keihin Fcr Carb Tech Float And Needle Valve Photo



Keihin Fcr Carb Tech Float And Needle Valve


24 Lower the float and needle valve together. Carefully guide the needle valve into the needle-valve seat. If the tip of theneedle bumps the seat, it will pop the wire loop off of the float and cause needless cursing. View Related Article

04.05.10 09:43Keihin Fcr Carb Tech Float Height Photo



Keihin Fcr Carb Tech Float Height


25 The manual outlines a method for setting the float height using a caliper. Davis uses a Honda tool that measures theheight of the float while lightly blowing into the fuel line. View Related Article

04.05.10 09:43Keihin Fcr Carb Tech Throttle Slide Lever Arm Photo



Keihin Fcr Carb Tech Throttle Slide Lever Arm


26 Lift the throttle-slide lever arm out of the way with one hand, and hold the slide (throttle valve) and the throttle-valveplate together with the other hand. Make sure the needle doesn't hang up while going in. View Related Article

04.05.10 09:43Keihin Fcr Carb Tech Thread Locker Photo



Keihin Fcr Carb Tech Thread Locker


27 The bolt holding the lever arm to the throttle shaft is the only one in the carburetor that calls for thread-locker (blue).Again, you may need a special Torx bit that is drilled to clear the center post. View Related Article

04.05.10 09:44Keihin Fcr Carb Tech Idle Adjustment Screw And Bracket Photo



Keihin Fcr Carb Tech Idle Adjustment Screw And Bracket


28 Insert the front float-bowl screws and snug them down, but remember to add the vent hose guides. Then attach andtighten the idle-adjustment screw and bracket. View Related Article

04.05.10 09:44Keihin Fcr Carb Tech Remove Screws Photo



Keihin Fcr Carb Tech Remove Screws


29 Using your good #2 Phillips, take out the three small screws holding the accelerator-pump diaphragm in place. Detachthe cover carefully so you don't lose the spring that rests on the diaphragm. View Related Article

04.05.10 09:58Keihin Fcr Carb Tech Clean Membrane Photo



Keihin Fcr Carb Tech Clean Membrane


30 Early FCR carburetors had much poorer accelerator-pump sealing, and the pump membrane could pack with dirt. Youcan see that only a little dirt has entered this pump and the membrane is in good condition. View Related Article

04.05.10 09:59Keihin Fcr Carb Tech Replace Diaphragm Photo



Keihin Fcr Carb Tech Replace Diaphragm


31 Replace the diaphragm, spring and cover; tighten the screws; then move to the top of the carburetor body andreplace the top. On a Honda, this wire holder goes on the front screw. View Related Article

04.05.10 09:59Keihin Fcr Carb Tech Fuel Screw From Zip Ty Racing Photo



Keihin Fcr Carb Tech Fuel Screw From Zip Ty Racing


32 Before installing the fuel screw in the carburetor body, first slip the spring over the end of the fuel screw, followed bythe washer and the O-ring. This Zip-Ty screw comes with the new parts. The rubber covers are separate. View Related Article

04.05.10 09:59Keihin Fcr Carb Tech Tighten Fuel Screw Photo



Keihin Fcr Carb Tech Tighten Fuel Screw


33 With a stock or aftermarket fuel screw, it should take between eight and nine rotations to fully tighten. If you get lessthan eight turns, don't force it. Check the threads on the screw and in the carburetor body. View Related Article

04.05.10 10:00Keihin Fcr Carb Tech Hot Start Fitting Photo



Keihin Fcr Carb Tech Hot Start Fitting


34 The stock hot-start fitting has a plastic 14mm hex that is a pain to get a wrench on. Zip-Ty Racing sells a billet-aluminum unit with a 10mm hex. If you haven't already, remove the hot-start plunger and check for corrosion. View RelatedArticle

04.05.10 10:00Keihin Fcr Carb Tech Float Bowl Drain Bolt Photo



Keihin Fcr Carb Tech Float Bowl Drain Bolt


35 Zip-Ty Racing also makes a float-bowl drain bolt with a magnet in it. We've tried them, and the magnet nearly alwayshas metal stuck to it. Now install the drain bolt (stock or aftermarket). View Related Article

04.05.10 10:00Keihin Fcr Carb Tech Attach Vent Hoses Photo



Keihin Fcr Carb Tech Attach Vent Hoses


36 All that is left is to reattach the vent hoses neatly, and the carburetor is ready to go back on the bike. Now just keep itthis clean, and your engine will stay very happy. View Related Article

Documents

To Kramer - Inchpincher · Keihin Fcr Carb Tech Fcr Body Cleaning The Keihin FCR Carb Rebuild With Zip-Ty Racing - Dr. Dirt 01 Ty Davis starts by thoroughly cleaning the FCR body