A syncing manometer.

[toglhot]

I've synced plenty of Japanese multis with vacuum gauges and a few twins, manually or with with looped, clear plastic tubes, both left me unimpressed, so I put together what I think is a better mousetrap.

Made from scraps which abound in my workshop, it cost me nothing. Two short lengths of 30mm clear acrylic tube, two short lengths of all thread and some nuts, four pieces of ply, two pieces of neoprene, some 6mm plastic tube, two 0.08mm Delrin jets I turned up on the lathe and a little water.

The top and bottom ply platforms sandwich the neoprene gaskets, which clamp on either ender of the acrylic tubes, held together by the all thread. A short piece of 6mm plastic tube links the the two tubes together at the bottom and two longer lengths of plastic tube connect the top of each tube to the two manifolds.

The action is nice and steady and rises and falls slowly thanks to the Delrin jets and the relatively large volume of water. There's not enough water in the tubes to fill one tube so no no risk of it being sucked into the inlet tracts. There was no inlet tract barbs to attach the two plastic tubes to, so I drill a hole in each manifold and pushed in a 6mm barb.

This video shows the MK 1 version. I later made a neater MK2 version (pictured).

 

[LXCam]

Nice job th. I’m going to install that in the memory bank. I tossed my carb sticks years ago but will will have the need again on an upcoming project.

 

[Modern Garage]

I've always synced my twins by sound. Maybe I'm overly sensitive but I just crouch behind the bike with my head centered and adjust the idle for the same level of sound from the left and right mufflers. Doesn't seem to matter if there's a balance tube or not , although I don't own anything with stacked one side pipes. Once the idle is even it's a simple matter to synchronize the throttles with the engine off so they pick up simultaneously from the idle stops.
I like the volume of your tubes - much nicer than the usual carb sticks.
Joe

 

[driftpin]

Looks like a good job, it seems to do the trick. I have several sets for 4 cyl's I've acquired over the years. They all pretty-much seem to provide similar results. I probably use my Bourdon tube set the most, I'd say it's ~40+ years old and purchased new.