LC50 Champ - very low compression!

Dale L /

Let me start off by saying, yes, I did download the service manual and do all the troubleshooting suggested.

I can only get 50-55# of compression. However, I can get the compression up to 125-130# by spraying motor oil in the cylinder. One time I was actually able to start it. It lasted 5-10 seconds and never happened again. This was after replacing 2nd jug/piston/ring and turning over multiple times, then removing compression checker and replacing spark plug. I have not been abel to get it to do it again.

Here is what I have done and replaced:

New battery

2 New jugs/pistons/rings - measured both - all numbers/gaps within specs - bought/tried 2 - still same issue

CDI unit (for LC50) - still same issue

New Magneto (for QT50) - replaced due to low spark, fixed issue with that

New Coil - still low compression

NGK Spark plugs - numerous times!

Left/right crank seals - replaced with new

Carb - replaced vacuum choke carb with non-vacuum choke - no difference

Carbs cleaned

I am getting fuel, as plug is wet and good blue spark

Timing seems to be okay - crankshaft keyway is correct (not sheared or bent)

Checked reed valve, have same compression with reed valves off of engine AND on the engine (to prove that the engine is actually getting air)

Exhaust pipe is open, no carbon

I am an experienced mechanic and have had 2 other experienced meachanics check out the motor and they can't find what is wrong with it either.

I am at my wit's end. I don't know what else to do. Any answers and/or suggestions would be greatly appreciated.

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