Carb Bench Alignment - does this look correct?

 2026-06-18 SG3 Final Alignment
Learning how to correctly set up these carburetors has been a painful experience.
I think I'm getting better though.

A delicate balance of a complex mechanical system as each adjustment interacts with another.

Posting this to KZ1300 forum in hopes Scotch or KawBoy or other more experienced person can provide feedback.
 

A small gap between the choke cam and roller.
 

Butterfly adjustment via synchronization rods.
 

I have learned to not put too much effort into this bench alignment.
The real setting is with engine running and measuring vacuum levels.
 

I think this is 'good enough' for now. 
 

Idle adjustment which impacts butterfly opening. 
 

A different view of same setting. 
 

None of the 6 carbs I've worked on don't have a gap.
Not sure if I'm repeating an error or if production didn't match engineering design?
 

Here's a pic and instrtuctions from the FSM which show no gap.
The idea being the bracket absorbs the spring pressure, relieving stress on the syncronization rods.

That's the theory anyway.  
 

In my opinion:
The sync adjusters are showing FAR too much thread.  This seems to be validated by the significant gap with the throttle-plates. With this much Gap it's likely to be a struggle to even get the engine to start and if/when it does you're going to have a HIGH rpm  "Run-away" !
Gap the throttle-plates to .006". I have a dedicated piece of brass shim-stock for this task which is 1/4" wide (maximum ! ).   
RE B12:  There is no gap because the instruction is to "Push the throttle grip completely closed. (the set-up with the 2 cable system) 
Re the fast idle screw/bracket.  In my opinion they folded it the wrong way !  Never-the-less - it's folded to provide more threads for the screw !

Scotch was right. 

1. Fired right up and settled in at 4k rpm.
2. Idle adjustment dropped rpm to ~3.5k, not much
3. Noticed contact being made on fast cam, backed screw out
4. Idle now too low - adjusted idle adjuster for ~1,200
5. Performed a quicky sync using Vacuum Mate - got it close very easily (a good sign?)
6. Went to adjust air idle jets... hmmm, maybe a couple of hundred rpm difference? But, engine sounded better.
7. Touched up the sync, got it withing +/-2.5 cmHg with FSM spec of +/- 2.

Not sure why the idle air jet has minimal results.

1. The circuits are open - Scotch tool used multiple times, low psi compressed air confirms free air flow
2. Jet 'tips' are clean and straight
3. OEM springs on idle air jets (length is correct)
4.  New O-Rings IIRC 2.5 mm as suggested by KB

How much difference should the idle air jet have on rpm? On  other bikes, if  fully closed, the engine stumbles, almost dies.  
Could it be I have an air leak in circuit thus reducing the effectiveness of the idle air jet adjustment range?

One last thought - in an earlier post I asked Scotch if the choke plungers were good. He said no. I forgot that conversation yesterday and haven't replaced them. Could this also be part of the problem?


Gaining proficiency takes time I guess.

d

 

"......Touched up the sync, got it withing +/-2.5 cmHg ...."

That's a difference of 1" Hg which I would never settle for.  There's no reason the 3 readings can not be exactly the same.  The distinct advantage of dampened analog (Dial) gauges over bouncing LED's.
You do not mention the final actual Vacuum reading.   7.5 Hg" to 8.5 Hg" should be easily achieved.  My '79 and '80 are both at 8" Hg.....for what it's worth.
 

scotch wrote:

"......Touched up the sync, got it withing +/-2.5 cmHg ...."

That's a difference of 1" Hg which I would never settle for.  There's no reason the 3 readings can not be exactly the same.  The distinct advantage of dampened analog (Dial) gauges over bouncing LED's.
You do not mention the final actual Vacuum reading.   7.5 Hg" to 8.5 Hg" should be easily achieved.  My '79 and '80 are both at 8" Hg.....for what it's worth.

 

Agree! Just wanted to get it close. Didn't want to chase perfection since idle circuits aren't in play yet?

Might you have any advice for me regarding idle jets having minimal impact to rpm? 

Not sure why the idle air jet has minimal results.

1. The circuits are open - Scotch tool used multiple times, low psi compressed air confirms free air flow
2. Jet 'tips' are clean and straight
3. OEM springs on idle air jets (length is correct)
4.  New O-Rings IIRC 2.5 mm as suggested by KB

How much difference should the idle air jet have on rpm? On  other bikes, if  fully closed, the engine stumbles, almost dies.  
Could it be I have an air leak in circuit thus reducing the effectiveness of the idle air jet adjustment range?

One last thought - in an earlier post I asked Scotch if the choke plungers were good. He said no. I forgot that conversation yesterday and haven't replaced them. Could this also be part of the problem?

Tomorrow is another day. Will remove rack, document current settings, replace choke plungers. 
Also going to re-read the info Scotch provided to a feller about 2 weeks ago. Hope I can find it.

Here's a short video of the Sync