Topic: Breaking in new rings

[Johnny5]

Okay, so what is the general stance on breaking in new rings on 750? There seems to be two camps: (Ride it like you stole it) and (Slow and easy for a few hundred miles).

[Cevan]

That's how I broke in my type IV in my 914.  What I did was a series of accelerations at about 1/2 throttle and then let off on the gas and let the car slow back down.  This puts pressure on both sides of the rings.  I avoided constant rpms for the first 500 miles.  I think if you go slow and easy, you won't seat the rings. 

[KingCustomCycles.com]

The cylinder temps will be the highest during breakin than any other time in the life of the engine.  It is the friction of the high points of the rings and cylinder barrel wearing each other down that creates the friction, and heat.  High combustion pressures, followed by times of cooling are the way to go.  Translated, that means highway driving, reving well in each gear, followed by cruising at lower rpm settings.  Ride it hard, but give it time to cool between. 

[Hinomaru]

Assuming that you are using Honda rings and the specs in the service manual, why not follow the owners manual for break-in? Granted it’s written for a new bike and a bit of overkill for ring seating, but the procedure works. Here’s the idea which was taken from a 750 K4 owners manual:

 
•          BREAK-IN PROCEDURE

Continued excellence of performance and economy depend to a great degree upon the treatment and handling given the first 600 miles of operation. It cannot be over-emphasized that not only will the engine benefit from proper break-in, but the motorcycle as a whole. During this crucial period the motorcycle must not be driven at full power over extended distances, nor should it be driven too slow. The general rules are as follows-

1. Maximum continuous engine speed during the first 600 miles must not exceed 5,000 rpm.

2. Increase the maximum continuous engine speed by 2,000 rpm between odometer readings of 600 and 1,000 miles, meaning not to exceed 7,000 rpm. Drive briskly,vary speeds frequently, and use full throttle for short spurts only.

3. Bear in mind never to lug the engine with heavy throttle at low engine speeds. This rule is applicable not only during break-in but at all times.

4. Upon reaching an odometer reading of 1,000 miles, you can subject the motorcycle to full throttle operation, however, do not exceed 8,000 rpm at any time (observe RED ZONE limit on tachometer).

NOTE: Do not exceed 7,000 rpm when running the engine without a load.