LCGB Forums

What does running in archive?
I don't run iron at the moment and I don't run nicasil in for more than 10 to 20 mile not sure why I bother with that.
How is an iron barrel any different after a thousand easy miles and if at all why isn't it built to be like that when new.

The ideal running in should be a lot of stop-start and up and down through the gears. This (in theory) will cause the barrel lining to run hot, then cold. This should case harden the liner making it less likely to wear, but the barrel which doesn't get as hot will still be able to expand........or so i'm led to believe

I'm not sure about the case hardening idea, I wouldn't have thought the barrel got anywhere near hot enough and would in any case depend on the carbon content (Italian and Indian vary). I think it is to remove the high spots caused by the machining process and allow the rings to bed in. Ceramic bores have a much smoother finish than cast.

as above I thought it was to remove any blemishes and unevenness in the bore and bed in the rings one thing I would say If you buy a kit and the recommendation is say run in for 400 miles and you don't and seize it (possibly terminal with nikasil ) you will have no come back with the supplier

So how long do you run in a new nicasil barrel and piston ? I been told to run in my new RT195 for 500 miles !

Hammer RB230 wrote:So how long do you run in a new nicasil barrel and piston ? I been told to run in my new RT195 for 500 miles !

Twice round the block then nail it





Well at least that’s wot I do

So running in a cast barrel is basically using your piston rings to wear out any imperfections.

Is there no machining process to do this

missing lynx wrote:as above I thought it was to remove any blemishes and unevenness in the bore and bed in the rings one thing I would say If you buy a kit and the recommendation is say run in for 400 miles and you don't and seize it (possibly terminal with nikasil ) you will have no come back with the supplier

About the same come back as you have if you seize it following the instructions.

Btw I fully accept I'am invalidating any warranty implied or given.

And just how would any supplier know how many miles you have done?
I once bought a brand new PX200 and took it up to London and back at full throttle off the clock. Never ever had a problem.
On a new build I like to run it in gently to bed in bearings seals rings etc. But I will never labour my engines and do what I believe is the wrong way by sticking religously to 30mph and 40 mph.
I like to keep it buzzing through the gears even if it means it runs free up to 50/60 mph.
Round the block a few times to make sure nothing falls off and all gears select. Couple of stress free ride outs and then we're done.

Scooterlam wrote:So running in a cast barrel is basically using your piston rings to wear out any imperfections.

Is there no machining process to do this

Probably not back then. At least not to that great a degree of accuracy. And in any case a cylinder will expand and contract as it gets hold of cold. So, how would you machine it perfectly? It's going to be off at some point. So running in probably gives you a good overall compromise.

How come you dont need to run in a modern car ?

because it's 4 stroke and watercooled

HxPaul wrote:How come you dont need to run in a modern car ?

Because they're aluminium ceramic lined and not big iron blocks, that's why they'll run for 150k miles without any major issues and an old fashioned iron block will wear and lose power and need reboring at half that.....IMO

missing lynx wrote:because it's 4 stroke and watercooled

But my strimmer and chainsaw are also air cooled and use 2 stroke but you never run them in.

I’ve had motocross and enduro bikes from new (2 and 4 stroke) and we never ran them in. 2 heat cycles on a paddock stand and that was the most running in they got. I’ve Just run in a ceramic plated barrel and new piston on my Lambretta. 150 Miles at varying speeds up to 50 MPH. Up and down the Box and not holding it at steady throttle for too long. A few plug chops and it’s done.

Have a look at these 2 articles
http://www.everything2stroke.com/conten ... ed-to-know
http://www.ashonbikes.com/content/running
My understanding was always- the run in process had 2 different parts -
bedding the rings and cylinder together, the cylinder takes the longer time
bedding in the bearings in- 100miles
Modern materials and surface finishes make the bedding in process easier and quicker.

Another factor with nicasil lined bores is that the cylinder being made out of a similar material as the piston will mean that they expand at more or less the same rate so there shouldn't be so many high spots caused by uneven expansion to wear away.

"Running in" is a legacy from the days when materials and tolerances were not what we enjoy today.
If you use yesteryear materials and foibles then running in is recommended as a precaution.
If you have the confidence that your superior materials, tolerances and engineering prowess are as good as you hope, then running in doesn't get much past the 1st warm up stage. If this wasn't true our racing fraternity would be in sh** creek.

I have nothing to back this up but heard one of the top race teams run lean till they soft seize then rub down the marks and new rings, job done.

We always used to call it “knocking the edges of it”