take the can off and put the stock one back on! depending on rules they base their classes on a can will typically put you into an improved/modified class.
if you have the time and money, for that f7 buy yourself a timing advance key. its a cheat thats legal! look at the isr rules.
traction is king, so stud up if you can. suspension settings are a key as well. loosen the preload on the ski shocks and remove the carbides. stiffen up the preload on the front of rear skid shock and loosen the rear of rear. then adjust your limiter straps to pull the front end up and hold about 6" off the ground for the 500' pull.
next would be clutching. you want the secondary to shift as quick as possible without bogging the motor. a shallower angle helix will help. you may have to load the primary a bit on the tip. if you have an option for a softer compound belt, run it.
is your sled injected or carbed? cant remember. those f7's were always a challenge for our yamahas. carbed will require adjustments for the day, temp, and barometric pressure. have jets and know-how.
practice, practice, practice! if you have a spot you can run wfo with a safe shut down area, use it. test the clutching and take notes. a mule sled is your friend at this point, not the 501 dyno. if a set up feels faster to you, its probably not. you need the mule sled for comparison. pace off the 500' and have a timer. watch your tach and speedo, take notes, make changes, repeat.
reaction time. races are either won or lost due to the lack of or ability for. heres the biggest trick for a beginner dragger: enter as many classes as you possibly can. by returning your sled to stock(back to the stock exhaust), you can enter as many classes as your wallet will allow at the 700cc level or above. its perfectly acceptable to run your sled in the 700 stock, improved, modified and then you can bump classes. run the 800 classes as well. i used to run my 600 stock appearing all the way through the open class. never forget the look on the big boys faces when that little well tuned sled would take them down.
so theres a few hints to get started. testing, notes, and practice are your keys to win at this point.