2105 Husky FC450 maintenance?

The guy you bought it from sounds like a retard.

You can get away with an oil filter change every other oil change, but as a general rule of thumb in my garage, I perform an oil & oil filter change every 5 hours, or 3 rides, whichever comes first. I ride a lot of sandy areas with a lot of hills, so YMMV. If you aren't riding the bike really hard, you can probably go further on your oil change intervals. If the shifting feels "notchy", its time to change the oil.

I clean the air filter after every ride.

I also change out the fuel filter in the quick disconnect section of the fuel line every other oil change, which may be overkill, but I don't need the bike bogging on me when it could be prevented over a $4 filter.

Your bike will run 91 octane pump gas no problem, unless the dude before you mapped it for race fuel. If you want to run race gas but don't want to break the bank, I recommend VP T4.

i had one it was a solid bike i changed the oil every 3 hrs, ran pump swill 87 octane that i run in my truck and every four stroke ive ever owned, kept the air filter clean, i only put 37 hrs on it and i think i changed that inline filter once, i did turn up the TPS voltage to make it responnd better, an i changed the oil filter with every oil change, also on the rite hand side under the seat , the voltage regulator is rite there make sure the wires going to it are rooted corectly my seat rubbed threw the white wire and my bike had no power the wires go under the frame and not over the top where the seat can hit them

Don’t run 87 octane in your bike.

2105? am I missing something?

Yes, sorry to say you have been in a coma for 87 years.