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How to syncronize motorcycle carburetor balancing with Vacuum Manometer Tool on a caf racer

Balanced my carbs on the café racer motorcycle with my bad ass DIY Vacuum Manometer Carb Synchronizer Tool. Works awesome and so much cheaper than motion pro vacuum gauges !

My cafe racer engine runs a little rough and i’ve checked everything else out so today i need to sync them up using a manometer i don’t have one so i’m going to make one this morning when you step on the gas it opens butterflies inside the carburetors it’s hard to show that with them assembled and on the bike so i made this diagram but when the throttle is closed

It basically looks like this and when you open the throttle the butterflies rotate and allow an air fuel mixture to enter the engine will throttle open throttle closed what i need to do is synchronize these two butterflies so the vacuum measured on each carburetor is identical this is what out of sync butterflies look like if one of these butterflies is open a

Little bit more or closed a little bit more than the other one you’ll have an imbalance in the carburetor flow there is a linkage that connects the two butterflies and to sync these up so they both open and close the same amount all you do is turn the screw there’s a vacuum port on the side of each carb and that’s where i will hook the vacuum line up to sort of

Base and some vacuum line and some fluid that goes inside i’m going to use this fish pump hose as my vacuum line to make my manometer out of this old yardstick my meter needs to be 92 centimeters long give it a nice coat of paint i need some index lines to measure the carb balance now my vacuum line needs to have equal length ends i need some holes in the manometer

Scale to attach my vacuum line i’m going to use green kevlar zip ties to attach my vacuum hose and i’ll hold the vacuum lines on the top with some assembly tape before coil in my manometer so the way this works is if the right side has more vacuum the level will rise if the left side has more vacuum that level will rise so now i have my completed manometer hooked

Up i’ve got the vacuum lines going to my carburetors so now when i fire it up since it’s a continuous loop and then i just need to adjust the screw on the carburetor until i have equal vacuum this right side has a lot of vacuum so i’m going to turn this screw and adjust that back down that’s about as close as i can get that’s how you make a manometer for vacuum

Balancing your carbs i just need to get some extra plugs do some plug chops to make sure that my tuning is all correct don’t forget to subscribe and i’ll see you guys next week

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How to syncronize motorcycle carburetor balancing with Vacuum Manometer Tool on a café racer By Ichiban Moto