Running in a new motor

[redbloke1956]

Hi all, Ducdude brought attention to an interesting/controversial subject on ancient vehicles in his thread "New Shadow motor now what do I do? "
and that is to do with running in a fresh motor, my understanding of modern motorcycle and car engines is that they require little, if any, running in.
Therefore if an ancient engine is rebuilt with low expansion pistons and rings made with modern materials and clearances, barrels supposedly machined to finer tolerances etc, should we start to re-think our preconceived, 60 year old notions on running them in?......just a question, not a statement!!

Kevin

 

[Dinny]

I have run mine in carefully, 30 mile short runs below 50ish to start, running rich without letting the engine labour, oil change at 100 and 500 miles. Slowly building up the speed to now doing short burst of 70ish.

Now have 700 miles on it and starting to play with carbs leaning out. It has new bigend, mains, cams and low exp pistons. When it ran hot in the early days the pistons were my worry which is why I ran it rich.

Dont forget it's not a modern engine but a 60 year old air cooled engine, I'm sure there are many ways of running in but this is how I was comfortable and it will not go over 70 ish for any length of time until its done 1000 miles.... Off the roads of course...

I'm sure there are many ways to run it in but it's my bike and I ain't going to thrash it out the box after a full rebuild, this is what I am comfortable with. I know with rebuilt air cooled aircraft engines you run them flat out to start with but I think the difference is they are a lot easier to cool, just put the nose down...

Anyway, that way my plan.

Mark

 

[vibrac]

Talking barrels and pistons
Three laps of the circuit and thats run in for our racer tahts all you get for practice
bored and honed with that in mind
I dont have £100 spare for a test day run in
never any sealing problems always good compression
but
I always seem to end this sort of entry with this coment
I use Castrol R

 

[davidd]

I do exactly the same as Tim in both cases. On the street, I pick the halfway point and let the bike cool down over lunch or bring a book to read, then turn around and come back using his technique.

Racing there is little choice, except I use Mobil1 as Castrol R is not available. The leak down test is always less than 1%.

David

 

[Bill Thomas]

Hello David, What is a leak down test ? I have seen you talk about it but don't have a clue. Cheers Bill.

 

[roy the mechanic]

A leakdown test in english is called a cylinder leakage test. It is one of my favourite diagnostic tools! The principle goes like this- choose the cylinder to be tested, remove all spark plugs, turn engine to t.d.c, so valves closed, install hose in spark-plug hole, connect tester to air line ususlly 80-100 p s i connect meter to hore in plug hole, read-off percent leak to test, if test results low, listen at inlet valve,or ehaust valve, or head joint ,or crank case breather with stethoscope to pin-point laeks. Imagine you are asked to diagnose a v-12 water cooled motor for a suspected head gasket leak (as I have on many occasions) the leak tester will tell you exactly the one with the troubles.

 

[vibrac]

Bill
You and I did it at Cadwell when this club still ran races by standing on the kickstart...
Tim

 

[Bill Thomas]

Hello Tim, Thats the funny thing, I was a mechanic for 44years I even worked on Jag's for a few years, I have had the cyl, heads off a V12, What a job, The studs go all the way down in the water, and they didn't want to come off !!, But never knew about the leak down test, Feeling Old !! Cheers Bill.

 

[redbloke1956]

I have run mine in carefully, 30 mile short runs below 50ish to start, running rich without letting the engine labour, oil change at 100 and 500 miles. Slowly building up the speed to now doing short burst of 70ish.

Now have 700 miles on it and starting to play with carbs leaning out. It has new bigend, mains, cams and low exp pistons. When it ran hot in the early days the pistons were my worry which is why I ran it rich.

Dont forget it's not a modern engine but a 60 year old air cooled engine, I'm sure there are many ways of running in but this is how I was comfortable and it will not go over 70 ish for any length of time until its done 1000 miles.... Off the roads of course...

I'm sure there are many ways to run it in but it's my bike and I ain't going to thrash it out the box after a full rebuild, this is what I am comfortable with. I know with rebuilt air cooled aircraft engines you run them flat out to start with but I think the difference is they are a lot easier to cool, just put the nose down...

Anyway, that way my plan.

Mark

Hi Mark, Thanks for your input mate, my plan was always to be something similar to your own .....I was just interested in hearing others views, taking into account current technology and lubricants etc, my interest was piqued when I saw a doco on TV about the Harley factory.
In the show they had an engine straight off the assembly line, lubed,warmed up and then a full dyno test including near max revs, the engine was then put back into the line?

Kevin

 

[davidd]

Bill,

I am always surprised that more owners do not know about leak down testers. As Roy points out it is an excellent tool. It is a good way to figure out if your rings have bedded in after a rebuild, or that your vavle job needs a touch up. It provides repeatable and easily quantifiable results that can be compared to earlier results. It is cheap, easy and provides really useful information. That is probably why I keep asking.

http://www.harborfreight.com/cylinder-leak-down-tester-94190.html

David