Bench Sync Carb Question

I used the narrow strips of business card shims to do the bench sync.

Sync screw for 3-4 produces 3 1/2 turns up from full bottom.
Sync screw for 2-3 produces 3 1/2 turns up from full bottom.
Sync screw for 1-2 produces 1 1/2 turns up from full bottom.

Does the 1-2 result indicate that a spring or springs is/are tired and need replaced? Or might it indicate that a spring is wound too tight?

After thinking about it I would vote that the butterfly spring is too tight for Butterfly #1.

The real answer is ??????

 

I never kept track of the screw's exact location from bottom, but I can tell you that you did it right if the strip of business card slips thru the gap with the same "drag feel" on all 4 carbs.

And that your idle would be really high.(set idle to about 2 turns)

 

What I am concerned about is that I now only have 1 1/2 turn in available on that screw.

 

Shouldn't matter. Once you have bench synced, when you vacuum sync you will be tweaking screws. I doubt any of mine moved as much as a quarter turn when I vacuumed synced.

 

Double -

 

Ahhhhhh. Ok. That answers it.

On the subject of vacuum synching, I purchased a pair of Sears vacuum gauges and a pair of in-line restrictors from the auto parts store. The needles still jump wildly at idle.

Do I just need a more restrictive restrictor?

 

I used the red WD40 straw trick and a small fuel filter. I get a 10 to 20 unit jump and tune so they match at peak.

 

Ok, so its not just me. The needle jumps for you as well.

Thanks

 

yea I think it is nearly impossible to get it not to jump and still function properly at idle. I believe the carb sticks don't jump as much.

 

I have the set of four gauges. I use the restrictors with them and have very little if any jumping. They have to be almost totally closed off.

 

im in the process of trying my first bench sync... let me just say... im ready to throw the carbs in the river!! i followed the everything xj how to using two paper clips... got em pretty spot on, put em on the bike and it revved at 4 grand... revved smooth but high. the problem there was the idle screw was all the way out... so i couldnt turn it down. tried tweaking them while its was running but then revved bad and died. now i have to do it over again. im so frustrated and done!!! whats the advice here? 82 xj 650