I've always been under the understanding that the "pinching" test meant to pinch off the fuel line close to the needle valve totally until the engine dies. If your engine dies very quickly without speeding up....it is too lean. If it takes awhile to speed up then dies.....its too rich. If you pinch it and the engine speeds up and quits within a few seconds.....that is what your looking for. Either way....I was never a fan of the pinch test because its just too vague,and should only be used to aid in tuning. Keep in mind,the pinch test is done at idle too I think.