Hello everybody, I don't know it this is the right place, but here it goes, I would like to make a simple rpm meter for my motorcycle, but I don't really know how to do it, is there anyone that have some links about it so I could grab some ideas to make something that could work?
Thanks in advance 
a bunch of people have done things like that. If you search for 'motorcycle' in the box above you'll fing some samples.
does your bike have a tach. hookup point?
I will search about it, no it doesn't have a "proper" signal to read, only have access to the pickup signal, so making an input circuitry will be another challenge, but if it isn't difficult it ain't fun 
basic nutshell
you attach a small interrupter to the wheel (lets be proper, it is a motorcycle, maybe a magnet system, maybe optical disk) and a sensor to a stationary place
pipe the rough signal up, make it safe, clean it, and then read it
How you go about it depends on a ton of different variables, starting with what are you attaching it to, ie a 50cc scooter, or a 1500cc turbo crotchrocket?
The pickup is a magnetic sensor used by the cdi to sense the position of the crank and uses that information to make the ignition spark in the exact time/moment, I just want to buffer this signal and clean it up to connect it to the arduino.
The bike will be an 125cc 2 stroke, or some 50cc to 100cc 2 stroke racing engines, I think I already have some good code to do this, tomorrow I will post it here and I will test it next week in my university labs.
Attaching one hall sensor and a magnet to one wheel would make a very nice speedometer.
I made a RPM/speedometer attached to my bicycle. I used a reed switch and 2x7 segment display. After some difficulties with interrupts it finally worked. I based my code on a code I found on the Playground and showed the rpm of a computer fan. I changed that and added the display code, voila !
It should´t be to difficult to hook up a simillar system like mine but in stead of reed switch use the spark signal. There are also some kits you could buy, I remember one from a Greek company but I can´t remember the name :