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Adjusting Throttle Body Synchronization

13K views 13 replies 5 participants last post by  High Desert Raider 
#1 ·
Going through the "Periodic Maintainance and adjustment" chart, they note that from 4k onwards, you should adjust the synchronization every 4k. Do you need specialized tools for this or is it a mechanical(linkage) adjustment they are refering to? Anybody got any ideas?:shocked:
 
#3 ·
Thanks Rollinje,
Don't know how I missed that. Seems like a PITA - You really have to do that every 4k?
SYNCHRONIZING THE THROTTLE BODIES
NOTE:
Prior to synchronizing the throttle bodies, the
valve clearance and the engine idling speed
should be properly adjusted and the ignition timing
should be checked.
1. Stand the vehicle on a level surface.
NOTE:
Place the vehicle on a suitable stand.
2. Remove:



Rider seat


Rider seat bracket assembly
Refer to


GENERAL CHASSISon page 4-1.


Cylinder-#1 ignition coil cover
Refer to
ENGINE REMOVALon page 5-1.


Fuel tank
Refer to


FUEL TANKon page 6-1.
3. Remove:


Cylinder-#1 intake air pressure sensor bracket


1
Cylinder-#2 intake air pressure sensor bracket "2"
4. Disconnect:


Cylinder-#1 intake air pressure sensor hose


1


Cylinder-#2 intake air pressure sensor hose
2
5. Install:


Hose 1(Parts No.: 5JW-24311-00)


3-way joint 2(Parts No.: 90413-05014)


Vacuum gauge hose for #1 3


Vacuum gauge hose for #2 4


Cylinder-#1 intake air pressure sensor hose


5


Cylinder-#2 intake air pressure sensor hose


6


Vacuum gauge


Tachometer
T R . .
 
#4 ·
Throttle body - continued

Locknut (rocker arm adjusting
screw)
20 Nm (2.0 m
·kg, 14 ft·lb)

Tappet adjusting tool (4 mm)


90890-04133


Six piece tappet set


YM-A5970



Vacuum gauge


90890-03094


Carburetor synchronizer


YU-44456



6. Install:




Fuel tank

Refer to


FUEL TANKon page 6-1.

7. Adjust:




Throttle body synchronization




a. Start the engine and let it warm up for several


minutes, and then let it run at specified engine


idling speed.


b. With throttle body #1 as standard, adjust


throttle body #2 using the air screw


1(for

throttle body #2).


NOTE:




After each step, rev the engine two or three

times, each time for less than a second, and


check the synchronization again.




If the air screw was removed, turn the screw

3/4 turn in and be sure to synchronize the throttle


body.


CAUTION:


ECA14900



Do not use the throttle valve adjusting


screws to adjust the throttle body synchronization.


NOTE:


The difference in vacuum pressure between two


throttle bodies should not exceed 1.33 kPa (10


mmHg).



8. Stop the engine and remove the measuring


equipment.


9. Adjust:




Throttle cable free play

Refer to


ADJUSTING THE THROTTLE CABLE

FREE PLAY


on page 3-8.

10.Install:




Fuel tank

Refer to


FUEL TANKon page 6-1.



Cylinder-#1 ignition coil cover

Refer to


ENGINE REMOVALon page 5-1.



Rider seat bracket assembly




 
#5 ·
Throttle Body continued 2

Rider seat

Refer to


GENERAL CHASSISon page 4-1.

EAS20630


Intake vacuum


31.3


35.3 kPa (9.210.4 inHg)

(235


265 mmHg)
 
#6 ·
are you trying to tell me that every 4K miles, you have to adjust the sync of the throttle bodies?????
Ok, I need to hear from other people about this... no offense guys, but this sounds like more work than needed...
ANYBODY out there with this problem, and have they done it on their bikes? I have almost 7K on mine so far, and am wondering if I have to do this....
Open up my mind guys, and give me some scoop....:chat: damn, sounds like I bought a Hardley:gaah:
 
#7 ·
I don't know uncle Guido, but that is what it says in the owners manual's checklist. Now wether it is actually neccesary - that is the question I'm trying to get answered.........:gaah:
 
#8 ·
I know, and Im not bangin' on ya, its just something that I plan on checking out myself now... and if there is a prob with it, I plan on finding out... hang in there buddy, this thread and the people that are here, will find an answer for it.......these guys are great.......GUIDO

ok, lets open this for discussion, Jack, and Traider, and all that have over 10K, lets hear from ya...RK, you too...........
 
#9 ·
from what i understand, a lot of people who have had their tb's synched up it was like night and day. now, if your handy in the slightest you can buy the carbtune.com tool, for 100 bucks and be able to do it whenever you feel like it. 4k miles is a little overboard once you synch it up initially. honestly it could be that from the factory they may be slightly off, and if you do it again i think you should be okay fro another 10k miles to be honest. synching it though is a very easy process, if you can put on exhaust pipes, you should be able to do this if you just take your time and follow directions. i'm others that did it will chime in as well. i have just over 10k and i wanna do it real soon, but i did it on a buddies raider a while back. wasnt bad at all.

chris
 
#12 ·
Thanks for the info nunan0219. I temporarily borrowed one from a friend to perform the service, but my own Carbtune unit is underway. Got it for $107 from the manufacturer, and the cheapest on ebay was $125 used with no storage bag - go figure.

Anyway, this service is a pita! Can you hook up the balance tool right at the pressure sensor, or do you have to remove the airbox every time and hook it up right at the throttle body as shown in the pic on page 3-7 of the shop manual?
 
#11 ·
yeah, but just generic directions. nothing too specific, basically says to hook it up to a vacuum line going to each cylinder. but thats when u use the shop manual and adjust it from there. i'm going to be doing mine soon, just picked up the roadburner 2n1 pro's and wanna see how it does with those first and than sync the tb's up and see what it does than.

i'll def have one for ya. lookin forward to spendin a week down in nc instead of a day next year.

chris
 
#14 · (Edited)
Build your own throttle sync tool for 4 bucks.
Found this on the web. It was aimed at carbs but can be used for throttle sync.
Essentially it's a differential manometer and looks to be very accurate for balancing vacuum.
You may need to get vacuum tips for the ports to connect to and maybe a couple of restrictors.

Here's the Materials List for the $4 Carb Synchronizer Tool:
•20 feet of clear plastic (vinyl) tubing - inside diameter big enough to slip on the vacuum nipple of your carb (3/16" i.d. worked for my bike, but it's tight, maybe 1/4" i.d. might be better). 15 cents per foot in the plumbing section at my local 'big box' hardware store, Sutherlands.
•A yard stick - Home Depot sells an aluminum yardstick for under $2, but you can make a perfectly satisfactory gauge with a 3-foot piece of 1" wooden lathe for next-to-nothing. (For a 'professional'-looking gauge, I actually used a yellow aluminum 4-foot rule, but that was wretched excess at $5.)
•3M/Scotch/Whatever - clear mailing/packaging tape. You should have some of this left over from the Christmas mailing season; otherwise around a $1 a small roll (and you won't need much).
•2 short nylon zip-ties - You should have these in your garage. If not, buy them in bulk for cheap in the wiring section of Home Depot, Sutherlands, Ace Hardware, etc. - you'll use them and wonder why you didn't have them before.
•A tiny amount of automatic transmission fluid - Actually, just about any fluid works, including used motor oil, colored water, 2-stroke oil, etc. I chose ATF because I already had a gallon of it and (most important) it is really thin and is RED (which looks WAY cool as the indicator fluid against my fancy yellow ruler) and ATF won't hurt the engine if it accidentally gets sucked in the carb's vacuum port.

Building the Balancer

Fold your 20' of vinyl tubing in half and mark the center point. Lay your yardstick down flat on a convenient work surface (kitchen table or floor). Place the center point of the tubing at the bottom end of your yardstick (there is generally a hole at the top end of the yardstick - put the center-bend of your vinyl tubing at the opposite end of the yardstick from that hole). Carefully run the tubing up each side of the yardstick, making sure that the tubing makes a smooth, non-kinked bend at the bottom.

Use the clear packing/mailing tape to fasten the tubing in place on either side ( left and right ) of the yardstick. Thread the zip-ties through the hole at the top of the yardstick and snug the left and right side tubing to the respective sides of the 'stick with the zip-ties. You should now be able to hang your yardstick from the hole in the top ( I use a bungee suspended from a hook in the garage ceiling). The tubing runs around the perimeter of the yardstick and about seven feet of tubing hangs down from the left and right sides of the 'stick. I fold a piece of tape around each end of the tubing like a little flag and mark the left side with an "L" and the right side with an "R" using a magic marker.

Now, put one side of the tubing in the container of automatic transmission fluid and, using the other side of the tubing like a drinking straw, suck ATF fluid about three feet up into the tubing. Maintaining suction for a second, pull the tubing out of the ATF container and then raise BOTH ends of the tubing above the top of the yard stick. Temporarily fasten both ends of the tubing high enough that the ATF drains down to the loop at the bottom of the yardstick. I recommend leaving it overnight so that all the bubbles, etc. work their way out.

Once the ATF has settled into the bottom of the tubing, the balancer is almost ready to use. If everything has gone according to plan, you should now have a nicely graduated rule hanging from the ceiling with a thermometer-like tube running up both sides, with the red "thermometer" fluid about half-way up each side at identical heights. Cut a piece of black electrical tape just long enough to cover the width of your ruler and use it to mark the height of the fluid. Your super-accurate Carb Synchronizing Tool is now ready to use.

It looks something like this




Part number for a restrictor = Dorman 47303 for about a buck each.
 
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