The bike you have is the main problem.
It super responsive throttle, steering and brakes give you NO grace for mistakes no learning curve.
So you would be better off buying a cheap 250 which when you sell you will most likely get what you paid for it.
But even if you lost on it the experience skill and FUN you got from it will be well worth it.
You can't learn when your scared and if the bike is twitching and nose diving your going to be scared this is going to make you tight on the bars which is going to make it harder to steer make you run wide on every corner.
A 250 will help you with all the above.
It will be slower in every way= more time for you to react
select the right gear and speed for the corner,
more time to look into the corner and see where you want to go.
And when your back on the throttle it won't jerk the bike as bad and you won't chop the throttle as much (that's the No1 SR) copping the throttle your shouldn't chop it off you should roll off the throttle.
Rolling off will keep the bike from diving forward remember you want to be smooth and stable.
The same things applies with braking.
In a car you can you can get away with being a little ruff on them.
On a bike you need to squeeze the leaver feel the bite then brake harder then ease off the brakes.
The goal is not to have the bike dive on the front, lock up or suddenly release the brake and the bike bounces back up all the above will upset the bike before going into a corner.
If the bike is not settled before the corner giving it throttle is the only thing that is going to help settle it but your SRs will be making you chop the throttle or even brake when all the bike needs is some smooth throttle.
All the above comes so much easier on a 250.
Sent from Motorcycle.com App