Bench Sync Carbs

Could someone be so kind as to explain the proper way to bench sync your carbs. I feel that I am in the same high idle boat as leondegrance. As described, by bike is probably running way too lean offset by cranking up the idle screw. and unfortunately I do not have vacuum gauges.

 

I second this request, I have to have about 1/4 chock on to keep it running. I have read a ton on how to colortune, plug chop, etc but have not found much on just getting it to idle.

 

Your carbs are off the bike and on a table or bench?

Your #3 carb is controlled by the knob under the carb. You want to close this butterfly onto an object. (paper clip, 1/4 " strip of business card, the wire inside a bread wrapper tie)

With this object trapped in #3, you then shut another butterfly on another carb on another identical object, doing #1 last because #1 "leans" against #2.

When you have everything adjusted just right, a slight turn of the idle knob will allow you to drag these 4 objects out with the same resistance "feel". All 4 buterflies are opened the same amount.

Then, when you get the bike running, you have to sync all over again !!!
even if you get the bench sync perfect. Search topic- - manometer- - carb sync- - plug read- - bench sync

 

Here is a link to wal you through the process.

http://xjbikes.com/Forums/viewtopic/t=6366/

 

you will need 1 vacuum gauge, here is a picture of the set up I made, works real good & cheap.

 

What kind of vacuum gauge did you use, the regular automotive vacuum gauge needles tend to oscillate too wildly to read.

 

What is not shown in Wizard's set-up are 4 restrictors, which are just small tubes, the smaller, the better. Located near the carbs, I used 1 inch of the red tube from a WD-40 can epoxied into a cheap fuel filter to make a baffle. I made 4 of them. My rig is a 4 tube Manometer, that works like a mercury filled CarbSticks, but being water filled, it's 18 X more sensitive.

 

there is only one restrictor in my set up, it is a smaller piece of plastic tube inside the black tube with the wd 40 tube set in with silicone, if you look where it says 1 on the board you will see it is slightly thicker.

 

I bought some vacuum restrictors today at Advanced Auto, $1.88 each, perfect for the manometer. I just need to find the 4 way vacuum fitting now.

 

Bench Sync IS NOT Vacuum Sync.
Bench Sync is the mechanical synchronization of the Butterflys.

Use 1/4 Inch wide strips of Business Card and Slip them under the Butterfly at the bottom of the Butterfly and get the same "Drag" Feeler Guage style ... on all four Butterflys.

Adjust the drag on 3 using the Idle Adjustment Rod.
Adjust 4 to the same drag as 3 by adjusting the Sync Screw of Number 4

Match Number 1 -to- 2 by adjusting the Sybc screw on Number 1

Match Number 2 ... to the same drag as on 3 and 4 by adjusting the Sync Screw of Number 2.

Since #-1 & #-2 are married ... the Carbs should be Bench Synced after matching 2 and 3.
Tweak the Idle Rod and Sync Screws to get the same drag on the business card slips ... right across the board ...

THAT ... is BENCH SYNC.

 

I disagree.
On a bench sync, you would have to adjust #2 to #3 before adjusting #1 to #2. Because if you get that "drag feel" just right on #1, then move #2, you just moved #1.

One Starbucks double Mocha for Rick !

 

The procedure is to adjust One to Two.
One and Two are married.
Once One is adjusted to Two ... any movement of Two automatically includes One.

That's how its done.
But, it doesn't really matter on Bench Sync because you are adjusting them all independently, anyway.

On Vacuum Sync.
3 is the Base
Adjust 4 to 3
Adjust 1 to 2
Adjust 2 to 3
Bingo!