leak down test procedure

At the factory they would be put together dry , filled with oil, then the bike would be run on a rolling road through the gears - that’s before it’s crated & exported. I have still had bikes that have not run in after 500/ 1000 miles . Triumph had this on the 995 motors where they were burning oil through not having bedded in the rings through riding too gently, had it with GS1150 BMW engines as well. BMWs we used to put in a basic oil in instead of synthetic and they would sort them selves out- Triumphs advice was “ give it a good Birching ..”
Either way they have to run in under load, at running temp- too gentle and nothing beds in, too quickly and you can overheat the rings.
Most modern bikes run in under normal riding, so you just jump on them & go - just don’t redline it. Older air cooled stuff, Two strokes or anything with thick piston rings needs a more careful approach. Heat cycling is the norm for Chrome bore two strokes.
Running in on an auxiliary electric motor is pointless because nothing is at running temp. You must also be aware that a piston expands far quicker than the bore as it heats up- if you don’t warm the motor gently you can get piston “ cold “ seizure - forged pistons with big clearance will need warming up sympathetically. I built a Cosworth pistoned Fireblade that was noticeably mechanically louder than stock.
 
Exmoor beast said:
At the factory they would be put together dry , filled with oil, then the bike would be run on a rolling road through the gears - that’s before it’s crated & exported. I have still had bikes that have not run in after 500/ 1000 miles . Triumph had this on the 995 motors where they were burning oil through not having bedded in the rings through riding too gently, had it with GS1150 BMW engines as well. BMWs we used to put in a basic oil in instead of synthetic and they would sort them selves out- Triumphs advice was “ give it a good Birching ..”
Either way they have to run in under load, at running temp- too gentle and nothing beds in, too quickly and you can overheat the rings.
Most modern bikes run in under normal riding, so you just jump on them & go - just don’t redline it. Older air cooled stuff, Two strokes or anything with thick piston rings needs a more careful approach. Heat cycling is the norm for Chrome bore two strokes.
Running in on an auxiliary electric motor is pointless because nothing is at running temp. You must also be aware that a piston expands far quicker than the bore as it heats up- if you don’t warm the motor gently you can get piston “ cold “ seizure - forged pistons with big clearance will need warming up sympathetically. I built a Cosworth pistoned Fireblade that was noticeably mechanically louder than stock.
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Absolutely......knowing the piston metallurgy and piston manufacturing process is exceptionally important, especially with hypereutectic pistons now in the mix. Piston taper is critically important along with skirt length. It's important for the owner/end user of the bike to understand what is required for engine longevity. As you've stated how the bike is warmed up plays a significant role.

Through my experience I can see the bedding in/lapping of the rings to bore using the "cold rotation" (my verbiage for this conversation) process, bear in mind that we are using Hastings rings on a cast iron bore. Using the "cold rotation" process on a nikasil or hardened bore would be pointless.

I also agree that heat and ring pressure via the ring lands is an important part of the process.
 
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AJ said:
Hey Ian what changes can you see to know the rings have bedded in?
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As I've stated to Mr. E Beast below this is mostly appicable to cast iron bores.

You will notice a subtle change in colour and texture to the bore. It is quite sublte but once you recognize it you will remember it. On an exagerated scale, think of sharpening a knife on a whetstone. The proper hone also has to be in place for this to occur...... too fine or too course of a hone job and it won't happen..... you're looking for the Goldilocks hone ;)

Opening up a honing discussion amongst engine builders is akin to starting an oil thread in a forum. I do not have the experience to even attempt to achieve a proper honing finish. It is an art form and the great machinists and builders make it look simple....... It's critical to engine performance long term.

FYI The only place a ball hone will be used in Don's shop is to clean the toilet ;)
 
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