Break in part4

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After break in you should check small metal area.
If you failed break in without heat cycle.
Small metal receive stress,black mark appear.
And same as pin boss. 
If so your engine is short life and break conrod soon.
Important thing is uniformity.
Perfect break in engine make you feel little tick and feel break in uncompleted.
You should trust only thermometer and sense of top speed.
This is bearing outer holder.
If you stopped engine by out of gas when carburetor set so rich.
It makes rust soon.
This bearing is just after break in.

When you rotate crankshaft by fingertips.If you feel something noise.
You should check rear bearing,
It might be from rust,dust.,cake of grease.
Rusted bearing effect other components bad influence.
Rusted bearing rotate unstable.

It damage crankshaft pin.

And so big end metal.

It make back plate spiral mark. 

Then I said break in is most important for engine life.
It is point of no return.

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