Re: Model E type II carb, choke question

[Don]

I’m thinking it will be easier to diagnose the high speed problem, then perhaps this might take care of the low speed problem. Does the engine RPM surge up and down at high speed/in gear? I remember you saying something about the RPM would actually pick up if you pulled the throttle back off WOT a bit. Is there any way you could post a video of the engine running at high speeds/misbehaving? Yes, I understand that audio can be deceiving, but this might help us head in the right direction. I am assuming you have found the correct OMC jet tool and removed/inspected the fixed high speed jets also.
I know you have checked the belt timing, and carb sync. Your symptom almost makes me think the carb butterflies are able to go past WOT, but this is not likely unless the roll pin was sheared off. In any event, the carb is apart now, so this is surely easy enough to check out. I know this is unlikely, but is there any chance you have the plug wire firing order/location in the cap incorrect? I’m trying to remember, but I think you said this engine used to run correctly….If so, what changed between the time it ran OK and now? Even though the belt timing and plug wires might be right, perhaps there is an ignition fault/cap-rotor problem causing a misfire which might explain this problem. Even though the plugs might be new, that doesn’t mean they are good…Again, simple stuff first. Yes, you might have a faulty/stuck/broken reed, but I wouldn’t pull that manifold off until you have confirmed all the simple stuff is OK. You can peek down inside the manifold with the carb off with a light, perhaps you can see something this way without ripping the manifold apart.