Hi guys,
Im New at arduino and so i Hope you can help me. At Time i repair my old 50cc motorcycle. Now i would build a Controller for it who Print Speed km/h, rpm, Dist Km and enginetemperature. I would your á reedswitch on the Wheel for Speed and for rpm the Magnets on the flywheel or over the Sparkplug, i would your what is easyer.
I have a Arduino UNO and a 16x2 Display. The First Display shoud Print km/h and rpm the Second temperature and Dist.
I Hope you can help me
LG Jim

I tried using a reed switch to measure a motor, found that the vibration of the motor made it useless. If you can't get at the engine computer itself, then taking a tap off the distributor might be the go. Of course - you need to know what gear you are in.

An alternative plan is to use a GPS unit. It depends on how accurate you want to be.

... reedswitch on the Wheel for Speed ...

A "Hall effect" sensor is a better choice.
Here's an example data sheet: