High rpm sputtering

[boni120]

Hello, I have a 2010 Gilera runner 50sp (stock and fully derestricted)
At about 7000k rpm (near WOT and at WOT) while driving the rpm sputters up and down quickly, it mostly happens at about 50km/h (31MPH) and it will not go past 60 kmh  because of this. (Before winter its top speed was 75Km/h (46MPH)) 
 After winter  i replaced the carb gaskets/o-rings because they had started to leak and And I replaced the float, float needle and autochoke. I also had to replace the phonic wheel as the cable had snapped. 
I am unsure if I should change the jets or something else.
Main jet 66
Pilot jet 32

[90GTVert]

If those jets were working before and conditions are roughly similar, the jetting isn't likely to be the cause. It could be that float height is different with the new float and needle. Usually if float height is very high, it will overflow or affect the low throttle positions with richness most severely though. If the float height is low it could be running lean. What I call a sputter is rich or poor ignition. You say it sputters up and down quickly. If RPM is surging, that could be a lean condition. Taking a look at your spark plug may help to see if it looks fouled with fuel and/or oil or if it is light colored and dry.

You could try making sure the spark is good. It has spark or it wouldn't run, but is it strong enough? A spark strength tester is great, but you can take an old spark plug and bend/break the ground strap off and use it to test. That gives it a large gap to jump and it should still be consistent and bright white/blue.

[boni120]

I put the old float and needle in but it did not help. The spark is strong and has a nice blue colour.