My 97 FZR sputters when i get to about 65mph, what may be the cause

misfire? check for bad coil (your engine has 6 coils) not hard to replace.

most likely a fuel issue, clean carbs, check fuel filters( there are often filters inside the tank on the fuel pickup tubes) check vacuum operated fuel tap

Vacuum leak or weak fuel pump

how long has the bike sat? it sounds like your haven a fuel problem. i would start with the simple first fuel filter, fuel lines, vac. lines and intake boots. If you have a vac. leak it could cause it run funky. Check your spark and spark plugs, plug wires and boots. if you haven't found the problem yet you should look into your carbs, you could have trash from your fuel filter or gas tank if your lines are old they could have started to brake apart. If your ride has been sitting for awhile you could be facing clogged jets. I don't know how you are with taken things apart and putting it back together with no left over parts, but i will say that the carbs have A LOT of small parts. If you don't have any luck with simple check list and would to take a look into your carbs ill be more then happy to help.
Good like
Mark Woodring

sounds like fuel delivery, check ur fuel pump first....grab a cup pull the hose that connects to the carb and the tank should be (red) turn the bike on dont start just turn the key on, it should pump fuel(a pretty good flow) if its pumping carbs are possibly dirty, if its not replace it, is ur battery fully charged, and all post secure?

Sound like the slow jets/idle circuits on the carb are restricted or misadjusted.

Hi and welcome to FixYa,

Initially, inspect the burn colors of the sparkplugs. If they are very light in color, then it would indicate a lean mix

Offhand, a lean mix andsputtering would both indicate an air leak; too much air, too little fuel. Either or both could be caused by a torn or out of position air filter or the air box not properly sealed. Aftermarket free air breathers/filters such as those by K & N and/or non-stock exhaust could also cause this if the carbs were not re-jetted. In some instances, the needle height might require adjustment.

Good luck and thank you for asking FixYa.

1 maybe there is a diaghfram tear at your carb only 1 is funtioning and 1 block engine is running but under power
2.check your fuel line from tank to fuel filter then pump then carb
probally there is a debrie stuck in the pipe line or in your tank