Another carb sync question

[Kenreesesr]

A friend of mine who actually exposed me to the Vmax (very grateful), has a stage 7 kit on his. Now I know when I sync my bike, I sync 1 to 2, 3 to 4, and then side to side. My friend with the stage 7 kit is under the impression that the only sync that he can do is from side to side. He believes that syncing 1to 2, and 3to 4 is not done after a stage 7 kit. Is that true?, and if it is, why? I am very curious about this.

 

[mzbk2l]

Depends... one of the installation steps of the stage 7 is to remove the v-boost valve. If this is done, there is no way to sync 1 to 2 or 3 to 4 because the cylinders pull through each of the carbs equally with no v-boost valve to isolate them.

Many installers will simply unplug the v-boost actuator after cycling it fully open during an ignition cycle. This leaves the hardware in place and able to be used again (like for carb syncing) by simply plugging it back in.

How that step of the stage 7 installation was done on your friend's bike will determine whether he can sync 1 to 2 and 3 to 4. I have stage 7's and the unplugged actuator, and when I took the carbs off for a cleaning in March, I only synced the two sides together. After syncing, I still wasn't happy with the way it ran so I plugged the v-boost back in and synced all four. The difference was noticeable... I had that "snap" back at part throttle that I hadn't been feeling.

 

[SpecOps13]

What mzbk2l said, or a pretty expensive set of flow gauges that actually measure the air flow at each of the 4 carbs.:ummm:

 

[dannymax]

Never could figure out why the v boost valves get eliminated with some Stg 7's....I have two bikes with Stg 7's and left the boost valves in place on both of them. It make syncing so much easier IMO.

The Weber gauge tool is nice for doing Stg 7's but I like the Carbtune, you get to see how adjustments on one carb affect the other ones, etc....just gives more feedback.

 

[Rusty McNeil]

I left mine in w/o the servo and used a mechanical throttle stop screw on the cable to hold it open. Could close it for synching. Put the vboost back in with this new motor tho'

As mentioned before, if you've got the eliminator tubes in place of the Vboost butterflies its just about impossible to synch the properly unless you have that fancy air flow measuring weber style tool.

Or you can mechanically synch them to get it pretty close

 

[dannymax]

Got my boost wired to this switch that Mark-o gave me....thanks buddy!

I want it open...switch goes forward, closed....switch goes back....or anywhere in between. Open road she likes the boost wide open, in town driving it's better nearly closed, kinda fun to play with.

 

[tugla]

Nice switch Dan-o.....you sure that aient another nos activation switch lol

 

[thor_eyerdhal]

I make the sync with stage7 witout vboost valves, it is harder than with valves closed but it can be done IF using a good vacuum metering tool!
I use a Carbtune unit and it is ok, previously i tryed with 4 vacuum mechanical gauges, that was impossible (too jerky)

 

[tugla]

If you don't have the vboost using the visual method then the weber.....it's bang on....but life's easier with the valves there....also runs smother in traffic.....yami got it figured out pretty good from day one....