Breaking in a new engine

[Liveware Problem]

I pasted the below from a website, any thoughts from our more mechanically-minded members?

 

This is from a guy who claims to be a mechanic.

 

Link (but chrome said 'your connection is not secure' fyi):

http://www.mototuneusa.com/break_in_secrets.htm

 

The Short Answer: Run it Hard !

Why ??
Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.

If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ... 
How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure ?? Of course it can't. 

How Do Rings Seal Against Tremendous Combustion Pressure ??

 From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into the cylinder surface, to seal the combustion pressure as well as possible.  


The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run. 

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !! 

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

[Stu]

if the first 20 miles are the most important than everyone will miss that as the majority of bikes will be either run up on a bench or a dyno 

[potatobroxd]

Variable rev ranges are the best, fortnine did a great video explaining why and it does make sense logically. 

[Bender]

It's the way I've done it, few miles to make sure nothings a miss and away you go

[S-Westerly]

20 miles? Seems a bit daft to me. Bought my bike in central London and it'd done more than 20 miles before I was able to give it anything close to beans. Can't say the engine has given any signs since of being an unhappy motor. How'd I know?

[Liveware Problem]

4 hours ago, Stu said:

if the first 20 miles are the most important than everyone will miss that as the majority of bikes will be either run up on a bench or a dyno 

 

He does say dyno is fine too I think.

[Liveware Problem]

46 minutes ago, S-Westerly said:

20 miles? Seems a bit daft to me. Bought my bike in central London and it'd done more than 20 miles before I was able to give it anything close to beans. Can't say the engine has given any signs since of being an unhappy motor. How'd I know?

 

Good question! He has pictures of pistons taken from bikes run in gently and ones run in hard, apparently the former show greater signs of wear from gas escaping past the piston rings. 

[Gerontious]

I followed the guidance in the owners manual. It wasn’t exactly complicated or particularly onerous.

[Liveware Problem]

13 hours ago, Gerontious said:

I followed the guidance in the owners manual. It wasn’t exactly complicated or particularly onerous.

 

He is saying that the guidance in the owner's manual is wrong, generally. Although that would appear to make no sense on the face of it.

[TimR]

6 minutes ago, Liveware Problem said:

 

He is saying that the guidance in the owner's manual is wrong, generally. Although that would appear to make no sense on the face of it.

Until you require warranty work and because you didn't follow their instructions/ procedures 

 

Yes engines have advanced from 60 years ago with liners and better material and not casted or hand built with a Minky going fook it that will do , but anyone can make a you tube video and show you what they believe to be true and present ' evidence' to collaborate this.

 Doesn't mean its factually correct and lets face it VW made how many people believe their emissions data ? 

 

Nah i will stick with what i know and trust ..

[Bender]

I rebuilt engine in my car and hammered it from 10miles.

 

I followed manuf instructions for my van and it's using 1ltr of oil roughly 1.5 -2k miles which they say is fine so they won't do anything, car uses no oil, only place it can go is out the exhaust, should have just drove it normal

[S-Westerly]

I ran my bike in as per manufacturer's instructions in owners handbook. Wasn't difficult and as said by others means any warranty issues are likely to be honoured. The engine must be relatively robust as the warranty on the newest versions (still the same engine) has increased from two years to I believe 5. That might just be a cunning plan to keep you having the bike serviced by the dealer.

[Gerontious]

"If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again."

 

He makes it appear an inevitability.

 

That explains why every bike Ive owned from new has had to have a premature rebore and why the internet is crammed with people complaining about new bikes with smoky exhausts and disappearing engine oil.

 

Or maybe not.. as that has never happened to me.

 

He forgets completely the other reason for running in a new motorcycle.. its not solely about the engine. Plonker.

 

These armchair experts who think they know more than the engineers who actually designed and tested the engines, are a menace.

 

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Edited May 28, 2021 by Gerontious

[Bender]

Getting the rings bedded in is the main reason behind running in procedures.

 

Avoid idling, avoid high sustained revs, avoid long light loads, ie varied driving/riding, there is nothing to be gained by lengthy running in periods if it's not run in within a hundred miles it's never going to be.

[geofferz]

11 hours ago, TimR said:

Until you require warranty work and because you didn't follow their instructions/ procedures 

 

 

I doubt a brand has ever upheld this, if, indeed, any damage ever were to occur which I suspect is unlikely. 

 

When I ran my 2 new bikes in I basically rode them spiritedly but absolutely did not take the piss. Seemed sensible. 

[fastbob]

I do not accept the premise that the rings are forced against the cylinder wall by combustion . 

[Bender]

1 hour ago, fastbob said:

I do not accept the premise that the rings are forced against the cylinder wall by combustion . 

Google says it does so it must be true.

 

The pressurized gases travel through the gap between the cylinder wall and the piston and into the piston ring groove. Combustion gas pressure forces the piston ring against the cylinder wall to form a seal. Pressure applied to the piston ring is approximately proportional to the combustion gas pressure.

[DJP]

I've owned half a dozen new bikes and I've never "Run in" any of them.

 

I just ride normally - don't labour the engine at low revs and don't bounce it off the rev limiter. Other than that I ride the same whether it's done 10 miles or 10,000 miles.

[Gerontious]

52 minutes ago, DJP said:

I've owned half a dozen new bikes and I've never "Run in" any of them.

 

I just ride normally - don't labour the engine at low revs and don't bounce it off the rev limiter. 

Which is almost exactly what 'running in' a new bike involves. nothing special.

 

Almost word for word how 'running in' is described in the owners manual for my bike. 

 

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Edited June 6, 2021 by Gerontious