Front end wont turn

[Malcolm]

Hi Guys, I need help, I have an 07 GasGas 300 for over 3 years now, The problem is that no matter what I do I cant seem to get the front end to turn properly. I have lower the rear suspension with lowering links , ajusted the pre load to 10mm (258mm spring length), lowered the front forks to just under the bars, serviced the front shocks 115mm of 5w oil, set the forks to base line settings and it still under stearing. I have tried 3 differnt front tyres and run the pressures as low as 0.85 bar. Please help