Find the turn signal wires. They are gray and light green or just all gray. I don't know on your model. They may also contain a running light and if so, it will be a dark blue wire. There are a lot of reasons the turns may not be working. If one doesn't work, most of the time none will. Power goes through your turn signal switch when it is in one of the operating positions. The power goes to the flasher relay which causes it to blink and then back through the gray / green wires to the bulb holders. First thing would be to examine all you bulbs. If one is burned, replace it. Next, you might want to replace the flasher relay. If the bulbs are different wattages than were on the bike originally, the relay may not be able to handle this. Use a HEAVY DUTY relay... these are designed for trucks/cars pulling trailers. Next check all the grounds coming off the bulb holders. On the front, there are normally grounds attached to stalks via ground collars. These will plug into a plug in your headlight shell to connect with the main harness ground system. The rear turn signal bulb holders will have grounds that plug into the main harness ground. Make sure all grounds are clean and tight. At this point, if you still don't have turn signals, you had best pick up a test light... You can start testing for voltage with the test light along the path I described to find out where the stop in function is occuring. I like to use a test light better than a meter for this type job.
As far as the tach not working. Is it electronic or mechanical? If electronic, there will be a wire connecting the coil(s) to the tach... I am not real familiar but I would look for this wire and make sure it was connected. A manual might tell how to test an electronic tach. If the tach has a cable coming from the cam cover, then check the cable obviously.
The fuel gauge connects using a two pin connector connected to a similar connector under the tank. The only thing that would cause the fuel gauge to stop working if it had been working is that the thing isn't plugged in under the tank.
