I have a 2001 F4i. I'm only going around 90 miles before my low fuel gage comes on. I have been told I can go another 50 on that but recently after about 20 miles all the bars on the gage were flashing. I stopped and filled up and my tank and it was pretty much empty. Is this normal. I don't ride extremly hard.

 

That's really low mileage for a 600. The F4i is fuel injected, right? If so, lift the tank and check all the hoses - especially the ones coming from the fuel pump going to the injectors and make sure you don't have a leak. A 600 should get mid 30's to low 40's depending on the rider's style.

 

my reserve light doesn't come on until after about 160 miles....

 

That surely isn't right. If you didn't buy your bike new, i'd check if there were mods done.