I would try the 13 driver with a 60 to 64 gear . With the 14 driver , the motor is bogging down in the corner to much as it is . That 17 driver will be even worse . If you have a tach on your kart , depending on what tach you have , you should be able to see the RPM highs and lows for each lap . A good handling kart may see 500 to 800 RPM drops , a Great handling kart may only see 300 to 600 RPM drops . Your target RPM should be the engines performance range , anything less your not using it all , and anything much over you are just turning RPM's . I still haven't heard if your running a True Predator (212cc) or a Clone ( 196cc) . 6800 rpm's for a predator sounds a bit high , depending on what has been done to it . We turn our AKRA clones about 6700 to 7000 , and that is with engine mods out the wazzoo . You want your engine to reach its maximum power range just before the corner , jmo , You might have to work on the handling of your kart . How much steering input are you having to do ? Watch the fast karts , and see how much steering input they are doing , with a Great handling kart , you will hardly see the drivers hands move the wheel at any time . You get close on the gearing , then working on the handling get easier .