Sync procedure question

i was re-reading my service manual--the section on syncing the carbs, and noticed that after balancing 1&2, and the 3&4, to then balance 1&3. When I synced mine, after getting 1&2, 3&4 done, I balanced 2&3. My bike runs great, and I can't think of any reason why the final balance couldn't be 1&3, 1&4, 2&3, or 2&4. Am I missing something?

 

Maybe.

Carb #1's screw adjusts only #1. When you move #2, it brings #1 along with it. Whereas #3 has no adjuster other than the main idle knob. And #4 is "all alone" on the other side.

 

ok, so screw #1 balances #1 carb to #2 carb, and screw #3 balances #4 carb to #3 carb, then screw #2 balances #2 carb (along with #1) to #3 carb which is already balanced to #4 carb. Therefore, it seems that either #1 or #2 could be balanced to #3 (along with #4), since #1 & #2 move together when using #2 screw. So in the end everything is balanced back to #3 carb. I think I'm going to test this this weekend and see if if makes any difference using #1 or #2 carb to balance to # 3 carb. Maybe they suggest #1 because the petcock can be hooked up to # 2.

 

I just got dizzy

 

The 1 screw's connected to the 2 screw, but the 3 screw's connected to the idle screw.

You could make a rhyme so everyone on here would remember. Like Roy G Biv

 

Know what you mean--and you just read it. I had to take a sea sickness pill after writing it!

 

You missed the point.

Adjusting #1 ONLY adusts #1. You can balance #1 to #3 all you want, but as soon as you move #2, #1 is going to move with it.

Adjusting #2 adjusts #1 AND #2. So once #1 is in sync with #2, you use #2 to bring the both of them in sync with #3.

The only adjustment for #3 is the main knob. It's "home base" sitting there waiting for the others to come to it.

Adjusting #4 only adjusts #4.

I like to do the 4-3 sync first, that way there are two cylinders (3 and 4) "working together" before beginning the 1-2, pair-3 dance.

When doing a carb sync the "factory way" the petcock isn't hooked up to any of the vacuum ports because the synchronizer has them all occupied.

 

That's what I understood and how I did it. But in the final balance I had my manometer tubes attached to the vacuum on # 2 & #3 carbs. For some reason the manual says to use #1 & #3, unless I'm reading it wrong. I'm just saying that I don't see how it would make any difference attaching the tube to either #1 or #2. Maybe they have their reason, but I can't see it.

 

When balancing the #1-#2 pair to #3 it doesn't matter if you are using #1 or #2 in any way as they move together and are already balanced to each other.

 

Sure.

I'm curious; what manual has you using a "2-hole" manometer?

 

The service manual didn't specify the manometer type. Page 2-12 of the 1985-1986 XJ700N Service Manual says: ...Repeat the same steps to synchronize No. 3 carburetor to No. 1 carburetor, then turn synchronizing screw # 2 until both gauge readings are the same."

I got the design for the two baby bottle manometer off this site. I just thought it was odd that they specified the 1 & 3 carb.

 

Ahh, gotcha. It's because they assume you've got a 4-tube manometer hooked up and are comparing all 4. Convoluted wording though.