Reply To: Timing a 6HP Johnson 1989

[Don]

OK, well I don’t see much wrong there, I’m sure that hole is not plugged also…The wetness looks like unburned fuel…If water was getting inside, you would see signs of rust in the combustion chamber also. That thermostat is probably missing parts like a relief spring, washers, etc, which is why it is so loose inside…Really don’t think that would affect the engine’s running this way.
The engine has the Q plugs, so that is good…Perhaps the bottom plug is NG, but I’m sure you have already replaced the plugs or swapped them. I don’t see any signs of overheat, the paint looks almost new and unburnt. You mention the bores and pistons/rings appear to be in good shape as far as you can see. So, the question is where is all the unburnt fuel coming from in the bottom cylinder….Is excess fuel being pumped into it somehow, or is a lack of proper crankcase sealing causing this mess. Again, pretty sure the fuel pump is plumbed into the top cylinder, and you have already bypassed the pump to eliminate it as a source of leakage…But, just recheck to make sure that the fuel pump is actually plumbed into the top cylinder….
Erratic ignition could certainly cause this, but I’m betting that UFI powerpack was replaced by the repair shop. But, perhaps the shop was not being honest, charged him for a new pack, but indeed never repalced it…Again, anything is possible here. In any event, please recheck the simple things I mentioned and be sure to eliminate the stop switch by simply unplugging the single black stop lead connector and running the engine. You swapped the coils, but the problem stayed on the bottom cylinder.
Please don’t forget about doing “verbal forensics” with the owner….Try to get all the details about when this happened and what may have been done to the engine that could have caused it…Was he running along fine, then the engine just started to misbehave? If so, any chance that he accidentally over revved the thing in neutral? Did he put the engine away, the it never ran right when recommissioned? Is this engine new to him, did it ever run right? Etc…
The only other thing I can think of is a plugged exhaust…Some of these engines, including the sailmaster versions have a plug in the usual gearcase exhaust snout. There is a big exhaust relief in the extension housing to help with reverse thrust. I have seen cases where guys convert these engines to short shaft and never remove the exhaust plug….It is easy enough to look in the gearcase exhaust snout, the plug will be obvious…This scenario seems unlikely though, but who knows…
A bad reed would certainly cause this issue, try peeking inside the manifold, maybe you can see something….Oh yeah, forgot you have to move the dang starter out of the way to get the carb off….You mentioned the repair shop allegedly put a new carburetor on this engine…Does it look new, any evidence of someone messing with the intake manifold, such as new gaskets or paint off the manifold screws? I don’t think the primer could be doing this, but pinching off the primer line is easy enough to try….Again, I would love to see a couple of the repair bill, and know if he got his old parts back from them? D
I realize you are going away, and the guy has a motor to use, so we can pick this discussion back up after you return….