Engine was in storage several years, I revived with new, non ethanol gas, etc., and carb 'boiling out', plus disassembly and meticulous disassembly and reassembly of the carb. Starts great, runs great -- to a point.
At about half throttle, the engine coughs and dies, but up to that point, idles and runs perfectly. If I snatch the throttle back, it recovers and runs well -- to that same half throttle point.
The carb WAS equipped with a .50mm pilot jet. I happened to have a .68mm pilot laying about, and installed it, expecting the engine to run way too rich, but it runs almost perfectly -- it still has a tiny stumble in the transition from mid range to WFO, but otherwise pulls like a mule all the way.
This engine has a fixed idle jet -- no adjustment, and its accelerator pump, while present, is disabled from the factory with a welch plug installed right in the output. (all the other accelerator pump hardware is in place)
I know these engines left the factory about as lean as can be for emission purposes, but I would have expected to remedy the half throttle issue with a jet just a few notches fatter. The change from 50 to 68 pilot jet has me concerned that there maybe an other issue(s).
Comments appreciated.
At about half throttle, the engine coughs and dies, but up to that point, idles and runs perfectly. If I snatch the throttle back, it recovers and runs well -- to that same half throttle point.
The carb WAS equipped with a .50mm pilot jet. I happened to have a .68mm pilot laying about, and installed it, expecting the engine to run way too rich, but it runs almost perfectly -- it still has a tiny stumble in the transition from mid range to WFO, but otherwise pulls like a mule all the way.
This engine has a fixed idle jet -- no adjustment, and its accelerator pump, while present, is disabled from the factory with a welch plug installed right in the output. (all the other accelerator pump hardware is in place)
I know these engines left the factory about as lean as can be for emission purposes, but I would have expected to remedy the half throttle issue with a jet just a few notches fatter. The change from 50 to 68 pilot jet has me concerned that there maybe an other issue(s).
Comments appreciated.
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