#1
The B string sound much louder than the rest. Is it to close to the pickups? Or is that explanation to easy..... I can't see anything wrong with the body or fretboard. Ofcourse it could be that the strings are ready to be replaced, I got as a second hand. 

It's a no name Strat with Humbuckers, the problem shows at alle pickup positions. 
Make love, not war
#2
I'd start with fresh strings and a setup, especially setting the string saddles to the fretboard radius.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#3
Quote by BlueGoat
The B string sound much louder than the rest. Is it to close to the pickups? Or is that explanation to easy..... I can't see anything wrong with the body or fretboard. Ofcourse it could be that the strings are ready to be replaced, I got as a second hand. 

It's a no name Strat with Humbuckers, the problem shows at alle pickup positions. 

I had this problem with a strat that had staggered magnets in the PUP's, the G and D were really loud.

The B may be to close to the PUP, you can try lowering that side of one pup see if that makes a difference, visually inspect the B string see if it's sitting lower than the others, a new set of strings, try all the easy no cost stuff first.