what's the best way to break in a fresh bore  and top end.

 how long of intervals and how many times should it be done

Also, according to the lt250r manual:
- less then 1/2 throttle for up to 10 hrs
- Do not maintain constant engine speed for an extended time period during any portion of the break-in. Try to vary the throttle position.

So maybe letting it idle for a long time is not the best idea?

Here is what Jerry Hall said about it in another post on here.


Just go ride it.

The piston needs more heat than what idling can provide to stress relieve it.  The proper break-in procedure will relieve the needed stresses and polish off the high spots on the piston and cylinder wall at the same time.

The heat cycle routine of letting the engine idle for ________ minutes with _________ minutes of cool off time and repeating the process ______ number of times, then run the engine at_________throttle position for __________ minutes........it just goes on and on and on........ just polishes the tops off of the cross hatch, glazes the cylinder and make ring seating take longer without doing much to aid the break-in process of the piston.  I have read and tried numerous break-in procedures in my career.  The above procedure is another one of those procedures that really does not hurt the engine but it does almost nothing to prepare or break-in the piston so that the engine is ready to be run hard.

When I have time I will post my procedure and the science behind the procedure.

I heard similar stories of factory riders just starting them up, cruising for a bit then hammer time. Was told if it's gonna blow up it would have already....