Two cylinder Vacuum Carburetor Synchronization Gauges

I'm glad I purchased these gauges! I had actually attempted to cancel the order after buying them, and was going to try adjusting my carbs without gauges first. The order was already shipped, so I decided to just keep them and try them out. I had already adjusted my bike's carbs just by ear, listening and adjusting until it ran the best, while I waited a couple of days for the gauges to arrive. When they got here I connected them up just to double check, and found my high speed sync was very near perfect, but the low sync was quite a way off. So I started over and synced everything up the proper way this time using the gauges, and man does my bike run great now! :) As for the gauges, I can't compare them to any others since I've only used these. They seem to be made well enough, pretty much what I expected. The hoses included are plenty long enough. I hung the gauges on the handlebars of my bike, and had plenty of hose to reach both carbs. (It's a V-twin cruiser, VS800 Intruder) The brass fittings screwed right into my carbs. Having one long and one short was nice, the short was was a perfect fit on one carb, while it was nice having the longer one for the other carb to clear the frame on that side. It made attaching the hoses easy! The gauges bounced around quite a lot, too much for an accurate reading, so I installed the little plastic restrictors in the lines close to the gauges. They worked well and were easy to adjust. When I started to sync my carbs, I first checked the gauges calibration by noting the reading on each carb, then swapping the gauges around and noting the readings again. They were close but not perfectly matched, so I opened the gauges and used the adjustment to get them perfectly matched. The clear face just unscrews off the gauge, then the flat head screw inside adjusts the needle. It's quick and easy. I may never need them again, but they've already paid off and were worth the purchase. If I ever need to balance dual carbs again, I know they'll do the trick! My only regret is maybe not buying the 4 gauge set, but then again I'll probably never own a 4-carb bike... lol

I have not used any of the other more expensive carb sync tools to give a good comparison, but this one did a fine job on my 1977 BMW R100RS. I had to use the plastic in-line valves to get the needles to stop jumping around, but once those were in place I was able to get my bike dialed in nicely. I have used this unit about 6-12 times as I'm a bit neurotic about motor synchronization and each time it has delivered. As others have noted, I do not pay attention to what is written on the dials, I just go off location of the needles during the process. For my bike I did not need to use the brass extension pieces, just hooked the lines right up to the vac port on my Bing 40mm carbs. Hope this helps future buyers.

This is a tool and works as it's designed to work. The blue plate the gauges are mounted to is metal. The face plates are plastic and it would be nice if they were glass, but if they were you break them and bitch about that too. So they did you a favor. ANY precision tool needs calibrating prior to use. Vacuum fluctuates and the needles are suppose to bounce rapidly. The tool is working as designed. The bouncing is actually a diagnostic aid of what is occurring in the engine and can be used to diagnose internal engine functioning. The restrictors are added to limit the bouncing of the gauges because you're using a vacuum gauge for something it was never actually designed to do. A manometer was designed to sync carbs. Back in the day manometers were expensive and there was also the obvious issues with the mercury. Someone came up with the idea, hey I could use a vacuum gauge (which every good mechanic already had) to do the same thing and get it close enough. Then someone with a brain came along and said lets try and limit the bounce of the needle and see if we can make it more accurate. Wow, look at that, it works! This is a quality tool that in the proper hands works as it's designed to work. For the most accurate results the resistors need to be installed and the gauges need to be zeroed to each other.

Gauges shipped and arrived on time. The gauges are well built, easy to read and display nicely. Syncing the two gauges to themselves was done easily by removing the cover, setting pointers in their appropriate locations, then using fine adjustment screws to set both gauges up exactly on a common vacuum source (IMHO, this should be done before using on any sync gauge set). Once the fine adjustments were made the gauges worked perfectly and allowed me to easily sync the idle speed and idle mixtures on my SBC’s two four barrel carbs. The gauges are a nice addition to my tool box.

Used these once and they seem to be acceptable for a rough adjustment but not for fine tuning. Neither of the gauges read "0" out of the box so you have to assume there's some error before even starting. I suppose you could remove the gauge indicator and re-zero it but I doubt that would be much help. For the price they're adequate. If you want better accuracy I'd spend a lot more for better gauges or take your bike/car to a mechanic.

I used this once, first time I synced carbs. The inline dampeners (forget what they are called) are definitely necessary. It's nice they are included. Worked well. I'm sure will be better each time with experience. There isn't a ton of hose, but it's enough. I couldn't figure out what the brass tubes are for, didn't use them. Maybe certain makes or models of carbs have a fitting for them. I just attached them to pre-existing vacuum lines (fuel valve line from one carb, and vapor recirculation system (whatever it's called) on the other). You may need adapters which are not included if your hoses are different size. Looks durable - the gauges are attached to a metal plate. Anyway, I'm satisfied and will use it again when the time comes.

Read the instructions carefully. The dials were not zeroed when it arrived. The little plastic valve are crucial in order for the synchroniser to work. I detected a possible valve leak with it and my carburetors are hard to synchronise

This product is very easy to use. While The fittings did not directly suit use on my BMW motorcycle, it was easy to adapt with a short section of larger diameter tube to go onto each carburettor. It was easy to calibrate the two gauges and stabilise the needles using the regulators which are supplied in the package. The dials are very clear. The packing case is secure and has room for the additional tubing that I needed to add. I'm very happy with the purchase.

Good product. Needle very unstable

Finally got the bike going and tried this product and it will not hold vaccum.thanks

I originally rated this as 3/5 but now after seeing that installing the valves supplied in the kit, you can get a stable reading. Those valves control the vacuum suction and if you tighten them up it will decrease the variable needle sway.