Mechanic Monday Tip of the week. MX Break in tips

Mechanic Monday Tip of the week. MX Break in tips.

This week lets wade in to a controversial subject. How to break in a new top end job.
If you ask 10 people how to break in a fresh piston and rings you will likely get 10 different opinions.
So here is my 37+ years as a mechanic and 2 cents worth of opinion on the art of breaking in a fresh top end.
    The most important aspect of a new piston and rings break in method is getting the rings to seat with the cylinder. If one misses this window of opportunity the cylinder will need to come back off and the glaze will need to be broken with a hone.

The break in procedure should actually start with the process of installing a new piston.

First. Give the cylinder a very light honing to clean up any glazing using a glaze breaking hone. Note: (the Nikasil should handle glaze breaking honing without any issues. If there is an issue with the Nikasil it is best to find out now before you toast an engine with a fresh piston)

Second. Only use a very light coat of normal engine oil during assembly. Do not use any special assembly lubricants on the piston, rings or cylinder.

Third. Start the bike and as soon as it warms up ride 3 laps trying to use as much 1/2 throttle as you safely can and avoid lugging the engine as much as possible.

Forth. Let the bike cool down. Then go ride 4 more laps trying to use as much 1/2 throttle as you safely can and avoid lugging the engine as much as possible.

Fifth. Allow to cool down then ride it normally but avoid lugging the engine for the rest of the day.

Like I said there are a lot of different opinions on this topic and many work well in seating the rings. If you would like to study more on your own you can do a web search about "brake mean effective pressure." This will give you a better understanding of how the rings are pushed out against the cylinder walls with engine compression.

Stay greasy my friends