Hi, I just had my 260 engine rebuilt. It is running like s**T. I did a poor mans compression test (finger over the spark plugs while cranking engine) and the # 5 seemed to have no compression. In any case the engine is under warranty and the company that rebuilt it seems to be rather clueless. I say this because they want to check the carbs as they think this may be the issue. Now I do not claim to be Mr. Goodwrench but my understanding of this engine leeds me to believe that if there is no compression or very weak compression it would either be the valves or the rings. Would someone please let me know if there could be other reasons besides the rings or valves or if I am clueless with my ring/valve theory. By the way they claimed they checked the valves and that they are fine which is why they are moving to the carbs. Thanks Glenn