Running in

[rosscla]

There's lots of advice out there on 'running in' you see ads with 'run in carefully' etc all over the place but what does this actually mean ?

There seems to be a received wisdom that you do X speed for Y miles / hours the gradually build up and at some magical figure it is 'run in'.

This seems to be more important on cast barrels than plated but some of the plated kits come with quite detailed guidance on extensive 'running in' periods whereas others are a few heat cycles and 'ride it like you stole it'.

You'll also see people who recommend various regimes including varying speed / revs / not labouring the engine etc.

Now I understand that you need to take it easy for a bit on a newly built top end or engine while things bed in and I understand that it's probably important on a newly bored / plated barrel that you need to let the rings flat off the peaks on the barrel hone but is there any evidence or science about how long this should take?

What is the actual purpose off running in ?

For plated barrels for example -
How long does it take to run in new rings on a previously run kit?
How long do you need to run in a new piston?

For iron barrels -
Are these values any different?

Is there any published evidence in either case that running in adds to engine longevity?

[Burnside]

From memory with the cast GT kits the suggested running in period is minimum 250 miles, 1st 100 miles @4% oil mix, use full throttle range but don't hold it in 1 throttle position for too long and don't labour the engine.

I own 2 of these kits (186 and 200) and I pretty much followed the above, essentially I just rode like I normally would but on local town/city roads were you are going up and down the rev range and through the gears regularly...and I ride quite aggressively. With new rings I just take it a bit easier for 1st tank of fuel to bed them in.

I have never understood the maximum speed running in guides, often you get people sitting in 1 throttle position for long periods and often labouring the engine up hills in 4th.

[LI150]

On a plated barrel I take it easy ish for about 100 miles then ride as normal but I have never been able to do this on cast. I am also interested in all rosscla mentions

[Meds1]

I run in based around AF Rayspeed method.
http://www.afrayspeed.co.uk/index.php?page=Per_rb20
Short heat cycles 10-20 miles for the first 100ish Miles zipping it up through the gears- and retorque
Similar for the next 200 increasing speeds- not letting it labour .
I run my RT as per MB advice - which is similar
The only one I didn’t was a TS1 - 50 miles on heat cycles and ride it like you stole it.

There a load off stuff around % and types of oil during break in floating around - the only manufacturers technical info I found on this was from aircraft.

[paul d]

I agree with Meds1. Heat cycles, gear changes to avoid labouring the engine and a retorque. I've always thought that cast barrels had microscopic hairs of metal in the bore from machining and the break in process was to wear these away to ensure a good ring/barrel seal. My GT kit definately ran hotter (cht readings) during the start of the break in process but ran cooler as the miles passed. I'd say it would've been easy to seize it in the first 200 miles if I'd caned it.

[fluff34567]

What about a rebuild that only had new rings on a cast barrel?

[fluff34567]

What about a rebuild that only had new rings on a cast barrel?

On a 100% standard engine that is.

[garry inglis]

new rings i do 50 to 100 miles then ride normal

[psychedelicropcircle]

Twice round the block then cain the c**t

[fluff34567]

Twice round the block then cain the c**t