A Proposed New Approach to Engine Break-in

The military has engine rebuild factories "motor" the newly rebuilt engine
by driving it with an electric motor for about 10 hours. No gasoline is
burned thus heat is minimized which is the enemy of any new or rebuilt
engine. The engine becomes warm from friction and compression strokes, but
never hot. The only pressure expanding the rings is compression pressure,
which apparently is enough to seat rings, despite many who say WOT is
needed along with varying rpm.

These motored engines are broken in without regard to parts "normalized" at
normal engine operating temperature. It evidently makes no difference to
the parts being worn in to fit.

I found this method fascinating and wondered if it could not be used after
a motorcyle engine rebuild. We do not have an elaborate test stand to
actually motor an engine, but the principle could be applied if the engine
is run in a certain unorthodox way:

1. Fill the oil tank with SAE 30 straight non-detergent mineral oil. Set
the bike outdoors and start the engine and bring it up to a constant 1500
rpm NO LOAD.
2. Use a garden hose and set the nozzle to a fine spray and continuously
play the hose on the head and cylinders. This will keep the engine below
212 degrees Farenheit as compared to as much as 400 degrees in slow speed
street riding. As bikes can be driven in the rain, this is not so much
different. By using an artificial rain, temps can be kept way down.
3. The engine is run in for about an hour under the above conditions which
is the close to motoring. This will break in the engine about 80% by my
estimation.
4. The bike is then run on the street moderately for another hour. After
that, the bike can be run normally for another 8 hours, then the break-in
oil drained and replenished with Shell Aero 80 or Walmart Universal Motor
Oil 15W-40. For bikes having a wet clutch, avoid anything rated higher
than SG. The advantage of aviation oil has to do with the additive package
which is "ashless and dispersant", having no metalic residue to foul
combustion chambers with hot spots prone to detonation.

Alternatively, a conventional way to break in the engine is just to drive
the bike moderately for a few hours and avoid the WOT thing. Its a good
way to melt new con-rod bearings. I really believe the reason for break-in
failure is the use of oils which are too good; those with
anti-scuff/anti-friction additives which simply do not allow enough
friction to do its work of wearing in the parts to fit. Instead, the false
idea of baby-ing the engine is given the blame. If cold motoring works,
then baby-ing the engine should work also; its the oil that makes the
difference. Use SAE 30 non-detergent and the engine should break in just
fine.

 

What a load of crap.

 

The depth of misinformation he posts is remarkable.

 

A new motorbike is like a virgin. It takes patience to break a virgin
in.

After anticipating the delivery of my new motorbike for weeks or
months, I certainly want to be the one who breaks it in by riding it
gently at first, I don't want to know about some machine motoring the
engine for 10 hours.

Gawd. What would *that* procedure add to the MSRP?

 

Spinning an cold engine for several hours? What exactly is that supposed
to do? None of the clearances are correct, there will be too much
clearance in the valves, too much in the con rod bearings, etc.

What the hell am I doing discussing the misinformation spewings of a troll.

pierce

 

You totally missed the point. I think he was talking about using new
motorcycle engines to help break in the motors they use around the assembly
plant.

 

Your right, i missed it. too little sleep makes one stupid.

pierce

 

well at least one thing is right when you break in a motor you should
use a non-detergent oil
straight weight ,it lets the rings seat alot better
but its not to be used continuously just for the break in then change it
out with the oil you are going to run (regular grade or synthetic) and
you will find the rings will keep a better seal a long time to come ,and
i have got this information from a couple different people who has
rebuilt engines for years from the old aircooled vw to high performance
v-8 engines

 

(badaztek) wrote in 3215.bay.webtv.net:

It isn't true with today's new engines. The break in period is short and the
manufacturers specifically say not to use a break in oil. Doing so will
render your warranty null and void. It used to be true in the 60's and
earlier, but things have changed in the last 30+ years.

pierce

 

I coulda sworn (badaztek) typ'd:

Uhhhh . . . no. He (and you) didn't even get that right.

Sorry, and thanks for playing.

-Don

 

"badaztek"? What, are you still lowriding the streets of Pacoima in a
Baja Bug, dreaming of Aztlan, homeboy? Haven't you heard of Integras
and Accords?

That rough hone, slow break-in thinking is outdated. Engine technology
has come a long way since the 1930's when the Germans literally
subscribed to the idea of the People's Car, and the late 1940's/early
1950's when Detroit offered inexpensive cast-iron V8's to the public.

Since the late 1970's/early 1980's, Japanese motorcycle engines that
have steel cylinder sleeves have been honed with a special
microfinishing process that leaves a smooth finish instead of the
cross-hatched swirling pattern that is supposed to retain oil...

Some racers I know actually went into the speed shop business and
bought an expensive microfinishing hone so they could bore out Japanese
engines to install big bore kits. Shop manuals used to specify piston
to cylinder clearances of up to .007" on some large bore engines.
Japanese engines were microfinished to a clearance of .0015".

When I took my Suzuki to the Vance&Hines franchised speed shop on
Sunland Avenue and specified .002", the shop manager said, "OK, but a
lot of the guys are specifying a *zero* clearance fit on those pistons.
I could do that for you, the piston skirts will conform to the cylinder
walls when they get hot."

Owners of older engines would point to those old fashioned rough hone
scratch marks when they'd say, "Lookie here, this engine's got 40,000
miles on it and the original factory hone marks are still there!"

Well, at least the cylinder bore wasn't worn and tapered .020 from top
to bottom like a Detroit cast-iron V8.

Nowadays, the piston rings should be seated within the first 600 miles.

But owners don't seem to understand how piston rings are playing into
the oil consumption "problems" that they perceive their engines to
have. They don't understand how the top piston rings seal the hot
gasses of combustion from getting to the residual oil that the oil
scraper rings leave.

The compression rings are really thin, in order to decrease their
weight. High performance motorcycle engines revving up to 15000 RPM
would have a serious problem with ring flutter.

High performance engines used to have problems with valve springs and
the valves would float, limiting the horsepower by limiting maximum RPM
the engine is capable of turning. That problem was solved and then ring
flutter became the limiting factor.

I once calculated that a piston ring in a Yamaha YZF-R6 was
experiencing acceleration forces of plus and minus 4000 times the force
of gravity as it stopped and started at the top and bottom of its
stroke. The onset of piston ring flutter occurs at engine redline, the
the combustion gasses
get past the rings, burning the oil film off the cylinder walls.

Somebody once asked Honda engineers what the redline on their
tachometer
really meant, would their valve start floating or would the connecting
rods break, or what exactly would happen.

As I recall, Honda wouldn't say anything about piston ring flutter, the
mystery of piston ring flutter was propietary knowledge, but Honda told
owners that they could cruise their engines near red line all day, just
keep an eye on oil consumption.

Most of us really don't get out and run at redline all day, the cops
are watching. We do get out and ride our high performance machines at
part throttle, and the thin piston rings don't seal well at part
throttle and oil gets burned off the cylinder walls and you hear guys
talking about how they didn't break the engine in right, or they
switched to synthetic oil too soon, they should have run dinosaur oil
longer...

The actual problem is that they don't run the engine hard enough to
develop enough cylinder pressure to seal those rings properly when they
are cruising around the countryside at 1/4 throttle to avoid getting a
speeding ticket.

Or they run the piss out of the engine and think it shouldn't burn any
oil at all.

And so you have a guy running around on a $10K, 150 horsepower
motorcycle, and he thinks nothing of buying a $100 box seat ticket to a
basketball game, but he bitches about spending $7 a quart for synthetic
oil and burning half a quart between oil changes.

Go figure...