Thanks for quick answers !
The reason is that the 2nd gear wont accept any throttle before it slips out
I got a good deal on a healthy engine and it sounded a lot easier to change engine than to strip the faulty one.
It might just be the gear forks that might need replacing, I didnt know that this was a standard Fzs problem before I found this forum..
I suspected that the gear was rounden and under load didnt hook up to each other (hope you understand my explanation....).
Anyway I bought this bike dirt cheap and therefor have a margin and was lazy and think its easier to just change the engine.
The bike have not been used in almost 5 years so I got a chock when removing the carbs !
All 4 needle valves are stuck and for some reason Yamaha have put in 2 screws in each carb, that is not rust proof....
Those screws will be replaced with stainless ones.
If you have more recommendation that I should do to get it of easy please let me know!