UPDATE! Christiano. i got my tach needle moving on iracing. but will not move past 2000. ive clipped the wires behind the tach for 4 cylinder. seems to be helping, still will not let me set it up in simdash to 10,000 or even 8,000. the sliders will not move the tach past 2,000. what should i do? 
Hello.
There is not much you have to do.
If you have configured the tacho to work with 4-cylinders and connected correctly to the rev burner, you should be able to push the needle up to 10.000 rpm, when you change the settings in the rev burner configuration screen.
If does not do that, I think there is something not working correctly.
I can replace your rev burner if you think it could be the problem, but I tell you it's very unlikely. Or it could be a problem with the tachomter.
can you get it replaced? what tacho is it?
Regards
Cristiano