Syncing carbs

Hi
I have a homemade nanometer which i hooked up to the ports the tubes of the map sensor go to. When i disconnected from the map sensor to hook up the nanometer the motor ran like sh.t so i turned up the idle to keep it running and adjusted the mix screws till the vacuum was balanced.... I just want to confirm i did this correctly....there are two other porta further up the carb with tubes ....... The mix screw did respond although the engine ran really rough

These are the instructions from the service manual. By disconnecting one tube only from the T, you are keeping the MAP sensor in the loop and avoiding the rough running.

Bloody hell , i know where i fubared,,
Thanks much.....

You can download the manual from the Facebook Silverwing owners page

https://www.facebook.com/groups/167150373692150/permalink/452001751873676/

Thanks a lot ..... i Really appreciate it.

Hello again
Wondering what the air screw position should be before synchronizing? No mention of it in the service manual

i think i got it now... so you adjust to balance and then increase or decrease the amount of air to increase rpm's, then balance again and repeat the process until the max rpms are reached.... then adjust the rpms to idle specs.... 1350 +/- 100 RPM.

The ultimate aim is to get the same vacuum in both intakes for smooth running, and the idle at the right point.

This image is actually of a VTX1800 V-twin but the Swing uses the same general layout. The idle screw and the fast idle wax unit interact, controlling a bypass around the butterflies (which are fully closed at idle). Then the two air screws adjust another bypass.

I'd expect you could achieve the right balance/rpm results with either the air screw adjusters just a little open and balanced to each other and the idle screw opened more, or the idle adjuster open just a little and the air screws opened a lot (and balanced to each other). Or anywhere in between.

Gonna give a try both ways as soon as the rain stops , I did get it balanced but for some reason the engine louder which brought this complexity on...thanks again eh

Balancing them is the key. Throttle bodies can become dirty after many miles it would be nice to clean both first but difficult on SW so much needs to be taken apart.

Since you already turned air screws there is no way of telling original positions and factory manual has no spec. for it only the guy at the factory knows. Start at maybe 1.5 turns out and set idle speed hot then balance them. If it takes more than 1.5 turns to balance than increase or decrease the other screw. Get them close and check idle speed and set them again. Screw are just air bleeds in throttle bodies.

What I did was loosen the idle screw 5 turns or so turned out the air screws about 5 turns balanced the carbs at this point......it was idling at about 1800 rpms. Then turn one side half a turn in and again. Balanced them and turned the air screw again half a turn balanced them using the other screw and repeated the process to 1300 rpm the set the idle to 1400..... Viola .... Smooth ride without sure or excessive vibration and the engine runs quitely again..... Thanks for all your help