Carb #1 Butterfly gap

[davesax36]

So I understand that the butterflies should be "barely not closed" when at rest. I'm guessing this is so the bike will idle. I'm wondering if there's a prescribed amount that I might be able to check with a feeler gauge so that I know that carb #1 has its fly open the right amount.:eusa_dancethat's what she said)

Anyway. Do you guys set your bench sync with feeler gauges, and if so, what's the usual gap for #1 as it's not adjustable and everything syncs to that one. I'm on a search for an air leak there right now, but I wasn't sure of the closed throttle fly opening size. Thanks

 

[MaxMidnight]

Dave

Assuming you are referring to the master butterfly that you sycnchronise the other to?.

The other three butterfly's are synchronised to #1 (master) butterfly so that they are open the same amount as it is.

#1 is then set by the throttle stop screw and the amount it needs to be open is governed by the tick-over speed.
As each motor is different there is no correct setting, i.e. the correct setting is the one that gives you the correct idle speed for a hot motor.

To isolate your air leak puff a little starting gas (e.g. Easy Start) and if the revs rise then you are in the right area.

 

[dingy]

The Ventures use #2 carb (LF) as the initial set point.

Then Sync #1 (LR) to #2

Then do #3 (RF) to #4 (RR)

Then do #4 to #2

Does the VMax differ from this?

Gary

 

[dannymax]

The Ventures use #2 carb (LF) as the initial set point.

Then Sync #1 (LR) to #2

Then do #3 (RF) to #4 (RR)

Then do #4 to #2

Does the VMax differ from this?

Gary

A little....

#3 is the RR and #4 is the RF on the V Max

After syncing #3 to #4 you sync #3 & #4 to #1 & #2 (with the adjusting screw on #4)

 

[dannymax]

Dave

Assuming you are referring to the master butterfly that you sycnchronise the other to?.

The other three butterfly's are synchronised to #1 (master) butterfly so that they are open the same amount as it is.

#1 is then set by the throttle stop screw and the amount it needs to be open is governed by the tick-over speed.
As each motor is different there is no correct setting, i.e. the correct setting is the one that gives you the correct idle speed for a hot motor.

To isolate your air leak puff a little starting gas (e.g. Easy Start) and if the revs rise then you are in the right area.

+1 Actual opening isn't what you're looking for as much as getting them close to the same....use feelers gauges, tiny drill bit, whatever will work for you.

-Get the plate openings as close to the same as possible

-Re-install, start the bike and adjust your idle speed (tick-over)

-Do a final sync

 

[davesax36]

ok. I think the vacuum leak was my biggest problem. My DIY manometer was sucking fluid evenly through 2-3-4 and 1 was just draining. I'll work on it again when I get a chance. Thanks, guys.

 

[sdt354]

+1 Actual opening isn't what you're looking for as much as getting them close to the same....use feelers gauges, tiny drill bit, whatever will work for you.

-Get the plate openings as close to the same as possible

-Re-install, start the bike and adjust your idle speed (tick-over)

-Do a final sync

+1 on the drill bit for a quick bench sync. A running sync. is always required if anything is disturbed. It's not a bad thing to check once a year as a habit even when runniing ok.
Steve

 

[maleko89]

One thing to check is making sure the valve is able to close all the way on #2. Do this by unseating the idle thumb screw all the way. On my old set I found dirt/grime on the return spring kept the valve from closing all the way so took some carb cleaner and then WD40 to clean it up.

 

[naughtyG]

That's what I would do - unscrew the idle screw and check all four butterflies are closing fully. The closer they are together, the better your bench sync.