OK, this has been my procedure for breaking in motors whether they have been my street cars, bikes, or race cars...
I have been doing this for not only my own engines but all the motors that I have built for customers over the last 30-40 years.
Once you have started the engine and got it to a stable operating temperature (with it being driven) and this is to be done within the first 20 miles of a new engine starting, take the bike/vehicle onto a road that you can legally get to about 60mph (or for some of you, down any side street...
LOL... Just j/k).
Ride/drive along at about 35 mph in top gear and then just open the throttle to full and accelerate up to 60mph (no need to go any faster) and then close the throttle to allow the motor to slow you back down to 35mph. Then ride along for about a mile at approx 40mph in top to stabilize the operating temperature. Then repeat this procedure about 5 to 7 times and that’s about 90% taken care of bedding your rings.
After doing this procedure, just ride the bike normally as you would everyday but not pu$$y footing it, but also don’t rev it high either for about the first 800-1200 miles... Never ever ride for periods at any constant speed especially highway speed during the first 1000miles as this can glaze your bores and will greatly reduce your ring sealing. If you have to ride freeway/highways, keep varying you speed and try and allow the motor to slow you down.
Now I’ll briefly explain why I do it this way. When you open the throttle wide open at 35mph it will load the rings hard up against the cylinder walls bedding the rings to the cylinder walls and as this will only be a few seconds before you reach 60mph there isn’t a high heat build up on either the piston rings or bore.
And then by closing the throttle at 60mph you will create a negative pressure in the combustion chamber which will help pull the oil up onto the cylinder walls and rings, and it will perform several functions, lubricate, clean and cool. Now before you start to say what about the bottom end etc, remember a couple of things, by doing this in top gear you don’t actually rev the engine and also its for a very short time to cause any problems on any lower end components plus the tolerance these days is held a lot closer than it used to be 10, 20 or more years ago, and therefore is not usually a problem with modern day engines (or newly built older one that has been clearanced correctly).
As bedding the rings is probably the most critical part of the run in procedure, because if you glaze the bores, well there's only one way to fix that and that's to hone them again. Think about it, bearings, rod side clearance etc all have clearances but the rings are pressured against the bore and need to have been seated correctly to a none glazed wall finish.
As I said this is how I’ve always done it and just did this same break in procedure to my 2010 Honda Shadow Spirit VT750C2.
Now I’m not into any debate about this procedure, I do it this way, not telling you too, but in 40 years I have never had any problems by bedding in any engine this way and will continue this way with any new engine I have...
