Vmax - running rough. Unsure what air pressure gauge is telling me

[gimgebow]

Hello.

I bought a carb sync gauge in an attempt to try to sync my carbs to see if that would help my vmax idle following this youtube video:


However, right off I noticed my pressure readouts look way different. I'm attaching a video of what I've got going on.

Can anyone help me with what these readouts mean?
From right to left it's 1st, 2nd, 3rd, 4th.

View attachment Image from iOS.mp4

 

[02GF74]

The different reading indicate the carbs are not balanced. Ignore the actual readings.
themselves.
You will need to adjust the synchronising screws until the needls are pointing the same.
If you don't have the service manual, here is the section.

 

[gimgebow]

The different reading indicate the carbs are not balanbced. Ignore the actual readings.
themselves.
You will need to adjust the synchronising screws until the needls are pointing the same.
If you don't have the service manual, here is the section.

View attachment 85205

View attachment 85206

Okay. I was afraid since they were drastically different, and one 1 and 2 the gauge says something about a leaking intake manifold that I wasn't going to be able to get it to sync.

 

[02GF74]

I would suggest trying to get the carbs sync'ed - you may need to repeat the process from the beginning especially if one of the screws is done up so it is coil bound (there are small springs over the screws that once coil bound, prevent further tightening).

If you fail to balance, that's when you should start to worry about air leaks - usual trick is to squirt carb cleaner or another flammable fluid at the carb/inlet rubber joints and if the revs pick up, that would inidicate a leak.

 

[Fire-medic]

I would suggest trying to get the carbs sync'ed - you may need to repeat the process from the beginning especially if one of the screws is done up so it is coil bound (there are small springs over the screws that once coil bound, prevent further tightening).

If you fail to balance, that's when you should start to worry about air leaks - usual trick is to squirt carb cleaner or another flammable fluid at the carb/inlet rubber joints and if the revs pick up, that would (sic) inidicate (indicate) a leak.

Yes to the concept. Don't neglect to spray the carb bottom to VBoost rubbers, and also the VBoost to cyl head area. There's a narrow O-ring in each joint of the VBoost to cyl head, and those can also go bad. If you find one is bad, replace the other three also, as you need to remove the VBoost manifold to do one. I use starting fluid to do the leak-detection spraying. I've heard of people using propane, but some numbskull not realizing how combustible it is, will do that in proximity to a gas hot water heater, and blow-up his garage/house.

You're looking for the needles to be equal by the time you get done fiddling with them. There's nothing wrong with the analog bourdon-tube gauges. I have an EMGO set I bought probably 40 years ago, and they still work fine. Each line has a small-orifice restrictor in it, to dampen the bounce of the needle, to make it easier to see them read 'steady.'