Carb Sync - #1 & #2 - Dumb Question

I borrowed a friend's Carbtune Pro.....

When sync'ing #1 & #2 carbs, isnt #2 carb vac line usually plugged into the vacumn side of the petcock.....

So when sync'ing.....I would think forget all that & hook # 1 & 2 to Carbtune Pro & go.... sync 3 & 4.....sync 2 & 3.....

I guess it doesnt matter whether the vac line to petcock is connected since fuel is in the bowls....

Is that correct......sorry for the stupid question......

 

You'll be occupying all the vac ports with the carbtiune. During the sync you'll need an alternate tank (smaller) above the engine gravity feeding the carbs. Or put your tank on a high shelf above and leave it on Prime

 

Vac line to petcock normally comes from carb#3
The petcock when on ON or RES is vacuum operated, so no vac. line connected disables the petcock. Put it on prime(PRI) when not running the vac. line.

 

vac line to petcock is currently on # 2 carb.......are you saying it is normally #3 carb......

I will switch then if that is correct.....does it really matter.....???

 

Technically, it should be plugged into the vac port on the 3rd intake plenum, but it can work from any vac port.

XJ purists like to put them where the Yamaha engineers put them!

There is also the fact that the 3rd carb cannot be synced, and that all other carbs sync to it, may have something to do with it, I don't know for sure.

I have found it easier to hook it to the 2nd intake plenum and it works fine.

 

It was hooked to #2 on the 550s and #3 on most of the bigger bikes.

It's not supposed to matter.

Put the petcock on PRI and prop up the back of the tank for adjusting screw access; no need to completely remove the tank even.

 

Thanks guys......I figure it didnt matter...a vacuum port is a port.....they all have one.....#2 or #3 carb is mostly likely candidate...

 

i just moved the gas tank over to where the seat sits. doesn't matter what vacuum port as long as the fuel switch has vacuum. my bike came on #2. but i have no idea what number owner i am. i could put on #1 but then it's on the outside looking dumb. #2 it's hidden.

sync 1 and 2. sync 3 and 4. doesn't matter which order. don't know about the carb tune. i have a home made setup. so i cap 1 and 4. then sync 2 and 3 for the final sync.

adjust air mixture screws first. then sync. and make sure you snap throttle after each screw adjustment. make sure everything comes back.

 

Carbtune Pro is a just a synch tool allowing one to hook up all 4 carbs at once.

Just have to make sure that fuel is flowing to the bowls......