Topic: Bench Syncing Carbs - Gapping Opinions

[mono]

If i only had a "search".  I actually googled, but could not find the specific answers i'm looking for, so here goes:

QUESTIONS/OPINIONS:  i have seen some people mention that they bench sync using a 1/8" spacer and some using 1/16" spacer.  I'm going to guess that the difference is probably significant, but i don't know enough to know which way i should go.  here's my current setup if anyone wants to offer their ideas.

cb550
Keihin carbs (same ones as here: http://forums.sohc4.net/index.php?topic=3920.0)
stock jet sizes (38s and 100s)
carbs dialed to factory spec
stock airbox with dry UNI foam filter
MAC 4-1

thanks,
 Dean

[bollingball]

Mono
The use of the drill bits is just to get the slides all set to the same gap. I like to use light. Put a light behind the carb and open the slides as soon as you see the light stop. If you have a dominate carb set the other three the same as it. You just want them the same and as small as possible As long as it runs you will be doing a running sync anyway.

Ken

[lucky]

Do you have the workshop manual?

[mono]

i have the service manual, but i didn't see anything in it about bench syncing the carbs - just taking them apart and putting them together.

also, i wanted to know why people used different sized spacers - wasn't sure if it gave a different effect. 

[flybox1]

Mono,
no different effect achieved.  (ive pretty much used whatever was within reach at the time)
think of it as a simple way to get all your slides to sit at the same height (relatively).
the vacuum sync, done at the end of tuning, will dial them in properly.

the only thing you need to check at the end of your bench sync is that your idle adjustment screw allows your slides to close all the way.  If you bench sync them with too big of a gap, you'll have a tough time dialing the idle down when the bike is running. So, after you bench sync, just turn the idle screw all the way out and verify the slides go down (no light shines thru from behind)

[mono]

thanks, flybox - this is the info i was looking for.  as i don't have a vacuum sync, i'm hoping the bench sync will allow me to get it running well enough until i can get one or find someone with one who is local.

[bollingball]

thanks, flybox - this is the info i was looking for.  as i don't have a vacuum sync, i'm hoping the bench sync will allow me to get it running well enough until i can get one or find someone with one who is local.

Mono If you get them really close to the same it will run quite well. Some people don't even do the final sync but you should.

Ken

[mono]

thanks, flybox - this is the info i was looking for.  as i don't have a vacuum sync, i'm hoping the bench sync will allow me to get it running well enough until i can get one or find someone with one who is local.

Mono If you get them really close to the same it will run quite well. Some people don't even do the final sync but you should.

Ken

I've heard that, and that's exactly what I'm hoping for.    I think even with a rough bench sync they'll work better than they did pre-sync.  they were pretty gross and the floats were all different and #2 was leaking when i got the bike.  i also replaced the manifold gaskets, so i might have something resembling vacuum now.  

thanks again for the education guys.  i really do appreciate it!

[lucky]

Also just look into the intakes from the air filter side and visually make sure all of the slides look the same level. The drill bit trick also works.

[mono]

i did the drill bit thing last night and it went pretty good!   now i just gotta get them hooked up (friggin airbox!)

[Deltarider]

 

now i just gotta get them hooked up (friggin airbox!)

Just practice Zen and the art of motorcycle maintenance.

[mono]

now i just gotta get them hooked up (friggin airbox!)

Just practice Zen and the art of motorcycle maintenance.

i was way off my zen last night, i tell ya.  i was cussing that airbox up and down.   

[Duanob]

now i just gotta get them hooked up (friggin airbox!)

Just practice Zen and the art of motorcycle maintenance.

i was way off my zen last night, i tell ya.  i was cussing that airbox up and down. 

You'll get it. After removing and replacing the carsb a few times you can do it in your sleep. I can have my carbs off the bike and back on with a running bike in 40 minutes not including cleaning the carbs thenselves.

Try pushing the carb rubbers into the venturi box when removing them while the airfilter box is removed. Do reverse when installing them. Also only unbolt the intakes from the head and remove by pulling straight out and twisting the carb assembly down and pull out to the side. Do the opposite when installing. Don't forget the orings to the intakes.

[mono]

yeah, last night (after throwing in the towel for the day) i went online and someone said they get them in again by just leaving the boots off of the airbox, and squeeze them in between after the carbs are on.  mine are still quite pliable, so i'll try that.

i really was in too much of a hurry last night, and we all know what that can lead to, so i just walked away and had a well-deserved brew. 

i also need to find a number of bolts for air filter box...   that was the 1st thing i removed i think, and i know i didn't bag those up.  though i had them safe and sound, but they are gone.

anyone know the bolt sizes?