Bike dies unkown issue

Hi all,
I purchased a 2000 FE501 about 2 months ago but I have never been able to rev it more than about 1/3 throttle or the engine dies. Person I got if off is no help.
I have replaced the Stator, CDI and put anther carb on it and it is still doing it.

When you rev it up, you can do it fast or slowly doesn't matter, after about 1/3 of the throttle - it will die. when it does it dies completely and doesn't start missing or anything like that.
When you ride it just using the first third of the throttle it runs well with no issues and has no other problems except when you rev it more.
I have run it without the air filter - makes no difference.
Basically you can rev it up hard and when you hear it die, if you back the throttle off to about 1/3 then it fires up again.
I have put another earth strap on - no better.
New spark plug and lead - no better.
I am at a loss to know what is causing it.
If anyone has any ideas please let me know.

Hi, I did use the same slide in the carb.
I changed everything else including the needle but not the slide as mine looked better.
I don't understand how this could cause the issue though ?

I have checked that the fuel flows well from the tank and it does seem to.

solved,
I took the top covers off the bike to inspect the valve adjustments and found that when you turn it over, the exhaust valves move correctly but the inlet valves only moved a small amount.
So took the cover off the top of the cam and found the issue. The lobe on the cam for the intake valves has almost completely worn off.
I suspect that someone has adjusted the valve clearances incorrectly and run it long enough to wear the lobe off.
Anyone have a spare cam shaft ?
Or know where I can get one ?