Zenoah GZ25N boggs down under load

[cpuaid]

So my trusty Zenoah GZ25N finally is acting up after many years of service on my GEBE kit. It starts up properly and sounds good and revs properly but as soon as you apply a load on it, it just boggs down and has no power whatsoever. Replaced the fuel filter, spark plug, rebuilt the carb, swapped out the carb, swapped out the electronics (checked gap), fresh fuel, etc. Tightened down all of the nuts and bolts, and sprayed carb cleaner around gaskets for leaks.The piston looks good and aren't scored. No smoke from the muffler at all. Clutch shoes are still in almost perfect condition and doesn't slip. Haven't tried swapping out the muffler yet or inspected the Reed Valves. Am using a spare Zenoah engine for now but would love to get this one up and running again. Always used the recommended 50:1 ratio with Lucas semi-synthetic. Any ideas out there?

 

[5-7HEAVEN]

Maybe the muffler is plugged after many years of use. Try replacing it or clean out with solvent.

 

[HeadSmess]

no smoke from muffler....hmmmmm?

so...there you are.

or, sorry...its dead. as a doornail. the chrome lining may be gone.

pray its the muffler, pray its the mufffler...

everything else seems a-ok...oh...reeds maybe even if it has em...