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With old not-recently run or even unused old-like new in-box motors, ALWAYS either tare the motor down or have it torn down and checked before use. Stuck wrist pins, stuck rings and rusty bearings are almost impossable to see and will shorten engine life. You may think you got away with it, and get a season or two before you notice a problem, but why do it? Parts are getting hard to find!! "

Courtesy of Eric V . Or Librerated Vis S. stunt ! .the above ! .

Thought Id follow my own advice & whip the backplate , Even tho the engine looked ' As New ' . Maybe run in, virtually no carbon discernable on piston .
Shoulda taken a picture before I got the C.R.C. & Heatgun on it . Only took six cans to get the wrist pin out. Or was it six goes .
Theres a 2.5 m.m. metric thread in the near end pad , so you can pull it from the wrist pin . 
Balsa Spacers so It can get going fwd. & back. Twisting .
Acetone & superglue can be used to glue in the pad . Tho not this time .