Hi there, I am about to overhaul the 748 but before I start does anyone know of any common problems with the vertical cylinder. Mine smokes...sometimes heavily on start up (depending on how much I've used it). if you don'rev it enough it oils the spark plug up and runs on one. top end problem but what....guides seals....anything else? Any positive suggestions would be appreciated. Thanks Jon
Is it only on start up? If so probably as you say, guides or seals worn, if it smokes after start up when running warm then it could be piston rings. Steve
such a difficult one to diagnose definitively - a leakage test is the best way to try and determine how rings are behaving but if you are stripping anyway.. Could you let us know what you find Jon as will be good to help build up general casebook history. From a cost point of view I hope it's stem seals/valve guides or if you're lucky just piston rings* rather than worn and/or scored bore/piston. The fact that you have bad plug fouling makes me wonder if it's the latter - how do comp tests compare front and rear? * some of the aftermarket oil control rings are not a patch on the original standard type with internal expander spring.
Yes guys, will keep you informed as I go. I was just wondering if there was something else to be wary of, obviously not. Thanks. Jon
