You won't get more power, just different power. Tightening the adjuster will delay the opening of the powervalve, generally smoothing the powerband, reducing the "hit". Loosening the adjuster allows the valve to open sooner, possibly enhancing mid-range power at the expense of low-end. If you make it too tight, the powervalve won't open all the way and you could break the spring. One quarter turn from stock, either way, seems to be the practical range of adjustment on my RM 125.