Two tech questions for anyone. Just traded for a interstate 1100, model 80. It has a broken rod,wrist pin or something similar.as the #4 piston doesn´t move on cranking over and makes a thrashing machine noise. With 77077 miles on the clock. Is this a common problem with this model??? The timing belts were both off the marks. Also, how far can you overbore this engine and still be dependable as a daily driver?? It´s my first wing. Dan