Hey, Randy! Ringed/BB engine break in

[Bill Little]

Hi Randy,

How about refreshing everyone's memory on how to break in a ringed, ball bearing engine.

Two examples:

1. One of your set up ST G.51

2. NIB HP .40 Gold Cup with hard chrome sleeve

Thanks!
Bill

[RandySmith]

 Break in on ringed motors is similar but not exactly like iron/steel lapped motors.
When you  use motors for the first time, you should also make sure you have the motor properly broken in.  This will range from six tanks of fuel for one engine to almost two gallons for others
A good break-in procedure is to use the same fuel as you will for your Stunt run ,and try to do your break-in on a bench; this is a lot better ,also an easier way to do a proper break-in.  
Use A diameter the same , or one inch smaller than you plan to run and a 3 or 4 pitch, should be the prop to use.  This will let the motor turn many revolutions more per motor run time.  Start out in a very sloppy four-cycle for cast iron lapped piston and  most ringed motors, slowly progressing to the fastest it will run in a four-cycle, then put it in a short two-cycle burst for short times.
The reason for going slow and rich on a ringed engines is this:
Many times I see people getting ringed engines much too hot to start off when brand new, this heats the ring, it expands so much that the end gaps touch, when this happens you now grinds/wears flat spots at the two gaps, this KILLS the ring seat/seal, Many rings come with a very small end gap, these are the ones that are the most susceptible to overheating , and destroying the rings. ST46s were very bad about this.
When you do this to a ring, the motor will never be good, replace the ring and start over.
ABC ring setups like HP and a couple other had , are much better about not doing this, but you will not run in to too many engines with that setup.
Do the breakin, it WILL pay dividends with a better running stronger, longer lasting motor.
After the correct amount of time it should be able to run in a two-cycle without heating up and going leaner. Using  3 to 6 ounces per run with 5 to 10 minutes  cool down time in between.
Many times you will know that the breakin is achieved when you put the motor in a 2 cycle and it snaps back to a 4 cycle very easy, with a tight ring, or not being fully broke-in it will do this slow or not at all.

Randy

[Gene O'Keefe]

Very good question Bill...guess I'll have to modify my break in procedure slightly (slow & rich).  Thanks to Randy for the expert answer.