point me in the right direction

[Genki_Desuka]

I just got a GS500E 1990. I changed all the fluids put new sparks in. Cleaned the tank and petcock. But I cant get the bike over 75 it dies out slowly, full throttle same with 5th and 6th gear. I would gladly appreciate it if someone could point me in the right direction here. Is it the carbs or air filter... not sure what else to check.
Also my Tach is stuck at 6k and goes up from there. Not sure how to fix that part.

[reload]

i will have to say fuel starvation on the engine dying issue. check the petcock. replace it with the newer model style.