With a tail dragger if you have to force the tail to rise on takeoff you can bet the plane is tail heavy. A properly balanced plane will raise the tail about 1/3 way through it's takeoff roll. If it's tail heavy your elevator response will be very quick making the plane porpoise. When this happens chop the throttle and drop the nose to regain airspeed and set it up on short final and land. Re balance the plane per the plans or instructions. Usually 1/3 of the wing cord measured at the fuselage center will get you into the ball park.