BACKGROUND:<br />I recently purchased a 1969 Merc 500, SN:2629914, that was supposedly in good shape with good compression, and used consistently thru last year, and was running this year in a barrel (I saw it (momentarily - it sputtered a bit but the gas tank was almost empty)). After purchasing it (I was greedy for more power, needed a shortshaft, and finally found one), I found the motor to start, idle when given enough gas, but die when putting even minor load on. Before digging into the carbs, I measured the compression for myself: 120, 115, 30, 120. Yikes! I remeasured #3 - it was peaked out again at 30 psi. I read from posts that differences in compression is not good, but I've not seen resolutions of this issue. <br /><br />QUESTIONS:<br />From past experience, what might have caused this, and is there any hope for non-professional (handy with normal tools but not in possession of specialized ones my Mark 55 always seemed to need) to resolve an issue such as this? Or did I just purchase a "parts" motor? I assume it depends on what is causing the problem. What can I do to determine the root cause ( bad rings, bad cylinder wall, stuck valve, what else??)? <br /><br />Thanks for any assistance you can provide.<br />Dan.
