Unable to pullup from a stop going uphill

Hi peeps. Have you experienced scooter issues when pulling up a hill from a stop? Got issues with mine, runs really fast on flat like 90km/hr. I can get up a hill fine but need some momentum. But then from a stop, i just cant pull away and i dont know why. Moves like 20km/hr and struggles that i just have to make a u turn. Also felt like it starts to bog down. Seen other 50cc scooters go up the same hill from a stop and they seem to pull up with ease compared to me? I currenlty have a stage6 70cc sports pro cylinder, technigas exhaust, stage6 sports pro variator, stage6 medium torque spring, 1000rpm clutch spring, and 4.5gm rollers. I think the previous owner of this scooter has up geared final drive with 15/42 ratio if i'm not wrong. I dont know if that affects uphill performance. I just couldn't gain momentum when going uphill from a stop. Does it have something to do with clutch springs for take off from a stop going uphill? I seem to have quite a good quick take off with it on flat but also felt like it engages a wee bit below the power band. Torque spring? I am not sure what rpm range my stage 6 medium is though. Any help, thanks.