Small Engines (Lawn Mowers, etc.): seized piston, pb blaster, piston kit

Question

2 stroke water transfe Hi Eric this question is regarding a seized piston in a 2 stroke water transfer pump engine.
I pump roundup through a "Selecta Power 1 inch Portable water transfer pump", manufactured by Silvan. (Australian company)
I observed a puff of blue smoke coming from the engine so I turned it off and then the recoil rope start, indicated that the engine had seized, when trying to start it again.
I have disassembled the engine and pump and have observed that the piston and bore are coated with what seems congealed grease?? The two roller bearings seem fine and all seals indicate no leakage of chemical into the engine.
What is the best penetrant to un-seize the piston and clean the cylinder? any ideas on the cause of the gunk coating the cylinder?
The 2 stroke engine model is "TU-26" and is a single cylinder 25.6cc with forced air cooling and electronic ignition.
I'm basically a novice at this and any advice will be appreciated
regards Mike

Answer
Kroil, PB Blaster and Zep Orange are good penetrating oils.  Kroil is the better of the three but more difficult to find.  I have never had much success un-seizing an engine.  Have you priced a new cylinder and piston kit?  It may be better to replace or rebuild the engine if you want to ensure it lasts a long time.

How much is a new pump?  If the parts cost about 1/2 the price of a new pump I'd recommend an entire new pump.

Eric