Lay ayain darwaish, udhar hoga mitho ustad, wo kar de ga thek. Jahan tak baat race ki hai, air filter k sath, towards the seats, there is a small screw with a spring on it. Us say ap khud set kar saktay ho. Rotate it clockwise, race increases, anticlockwise, it decreases. After even minor adjustment, halka sa race dena gadhi ko tu see if it comes back to your desired to rpm or not