So you mentioned a few things that you noticed.
1. The speedo doesn't work but some of the other stuff does.
2. It comes back when you hit a bump.
3. The spare speedo doesn't work.
It sounds like you have an interruption of electrical power to the dash unit or the ground leg from your dash unit. That means you have an open circuit somewhere between the power source, the battery, and the dash unit or to ground. If you had a short or a ground from the power leg you would have blown a fuse.
It's a time consuming fix, but not technically difficult. May be rather frustrating. Here's how to fix it. I don't mean to sound condescending but I don't know your level of experience tracing electrical systems so I'll go from the basics. Which should be able to fix this issue.
First download an electrical wiring diagram for your bike. Like this;
suzuki-sv650-wiring-diagram/.
Next set your volt meter to read ohms. That's resistance and most meters have the Greek capital letter omega for ohms. Check the wire from the battery/fuse to your dash unit. You should have very low resistance. Like 0.3 ohms or less. Then check to see the ground leg wire from your dash unit is going to ground. You should see a similar reading, very low ohms.
Now the tricky part is that you mentioned that it comes back on, or tries to, when you hit a bump. So probably there is a connection that is intermittent. So you now have to wiggle all the wires and connectors that could possibly be causing the problem. That's why you download the wiring diagram, so you can narrow it down to a few wires.
Or you could take it to a shop but they're going to do the same thing. Or maybe they'll just run a new power or ground lead for your dash unit. Good luck.
