A common Motorcycle maintenance task is to synchronize the throttle bodies on the engine to smooth out any rough idle. This is done by monitoring the vacuum on each throttle body and using the idle screw to make the adjustment.
While this sounds rather advanced, with a little knowledge, a few standard tools to access the engine, and a TBS tool (Throttle Body Synchronization); the maintenance item really isn’t that hard.
Now you can buy a tool or build a TBS tool using fluids and tubes (there are examples of this out there on the interwebs), but I wanted to use an Arduino and some electronics to build my own to do the job. This instructable describes my journey in making my own Arduino Throttle Body Synchronization shield.
Step 1: Research
There are many vacuum sensors available from your favorite electronics parts stores. The interesting range that I need to measure is around -33 kPa (-4.78 psi). This is the value that should be measured on my motorcycle on a single cylinder when the engine is warm and at idle. You should consult a service manual for the specifics for your engine. So I picked one that measured a range between 0 kPa to -50 kPa.
Then I needed to understand how to connect this to my engine. The service manual helps here also, but I also found many great write ups on the web. I just needed some standard engine vacuum hose with an inner diameter of 1/8th inch which will push onto a service nipple already present on the throttle body. This same hose will directly push onto the vacuum sensor. I found this in bulk at my local automotive store. I needed four hoses each with at least 3 feet length so I could put the Arduino and sensors in a safe place.