opinions on this break-in method

[jcs003]

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

i personally find it a risky.  this guy seems to be shooting from the hip with his assumptions of tribology.

share your opinions and theories.

john

[dirtyd]

I've heard of this from many forums for the past 10 years. I don't know but maybe this applies more toward 4-strokes. Seeing how there is more of the piston on 2 strokes that can expand and come in contact with the cylinder walls.

[F-Red]

This is how you would do a 4 stroke. I agree totally and use this. I would never do it on the 2 stroke. But hey, you know what opinions are like! :excitement:

[Bigred]

2 heat cycles usually 10 min each cool down after each 3rd time let it warm up get on go thro all gears or 1-3 twicr varying rpm no wot let cool 4th time let it warm up then ride it like ur being chased always worked for me. Hell this motor had 2 hest cycles thrn straight to the dyno wot lol runs great

[jcs003]

here is duncan racing procedures for 2 and 4 stroke engines:

http://www.duncanracing.com/TechCenter/2stkenginebreakin.pdf

http://www.duncanracing.com/TechCenter/atv_breakin4strk.pdf

they have similiarities but the 4 stroke is less one step.

john

[rsss396]

Long Low rpm break-in with very hot coolant
 IMO this helps expand the piston closer to a fully loaded motor but gives the oil a chance to protect the piston and cylinder

then after the initial break-in 1-2 short rides with various throttle positions then let her rip!

[mennis1971]

I agree with the fact that no amount of heat cycles or easy break in will fix something that isn't right. I used to do all that easy break in crap, but no longer do. It's either gonna work or break. I now(and have for awhile) do pretty quick break in's with no problems. I don't even jet extra rich for break in. I use the same mix ratio(32:1) for everything I own and jet to that ratio too. I do use different oils for different stuff. Non powervalve stuff gets 927 and powervalve stuff gets Super M. It's your stuff so break it in however you like, but that is how I do mine and have had no problems. A complete motor rebuild does get just a slightly slower break in than just a top end tho. The reason for that is because you have a lot more stuff getting broken in. Also I always make sure my stuff is fully warmed up before riding it, even after break in. I believe that is one of the most important things. I hate seeing people just unload their stuff and hop on it and take off quickly with little to no warm up.

[jcs003]

Long Low rpm break-in with very hot coolant
 IMO this helps expand the piston closer to a fully loaded motor but gives the oil a chance to protect the piston and cylinder

then after the initial break-in 1-2 short rides with various throttle positions then let her rip!

this is basically how i see it.  the piston and bore are only theoretically round and at full expansion there will be a friction force between the piston, oil and bore.  if you look at the stribeck curve there is interactions between all three.    of course tolerances play a significant role.  jerry could better explain this since he is an engine builder/engineer.

john

[Jerry Hall]

this is basically how i see it.  the piston and bore are only theoretically round and at full expansion there will be a friction force between the piston, oil and bore.  if you look at the stribeck curve there is interactions between all three.    of course tolerances play a significant role.  jerry could better explain this since he is an engine builder/engineer.

john

I use a break-in procedure that is unconventional by most engine builders standards. My experience indicates the common/age-old break-in procedures like many of the above links recommend, shows a miss understanding of what is happening or what needs to happen during break-in.  The age-old break-in procedures in the links also shows me that there is a lack of confidence in their machine work or the equipment they are using and or there is a lack of attention to important details during the assembly process.  Some of these shops are easy spot when you walk in and hear the sound of air tools being used for engine assembly, the technicians are having a rock concert, playing their air guitars or singing along with the music.  

It takes time and concentration to do good machine work and pay close attention to the important details when building an engine.  
 
My break-in procedure is similar to moto-mans procedure in some aspects but I do not think some of his reasoning, understanding of what is happening or needs to happen during break-in is supported by basic scientific principles.  When I have time, I will publish my break-in procedure and the science of what I believe is happening during my break-in procedure.

[jcs003]

yes, jerry.  i know contact mechanics and dynamics is the governing branch in mech E that explains and defines what is actually going on during break-in.  i hope to learn more about this in the future.  i have been learning microfluidics and its a cross-over discipline that the chemistry and mechanics work together and the tribology within microfluidics is very fun to learn.  i took tribology and microfluidics last semester and i enjoyed how they coorelated.

i am anxious to read your publication on the break-in procedure.

john

[wilkin250r]

I vehemntly disagree with one of his main principles.  In a section he calls "What about Heat Cycling the engine ??" he states that "Heat treating the metal parts is a very different process, and it's already done at the factory before the engines are assembled. The temperatures required for heat treating are much higher than an engine will ever reach during operation."

I'm not saying his break-in method is entirely wrong, just his logic on that aspect.  Most people would agree the main focus of any "heat cycling" is the targeted at the aluminum piston, and heat treatment of an aluminum alloy is actually VERY close to the temperatures found in an engine environment.  In fact, it is possible with a lean mixture to MELT an aluminum piston, do you really imagine that a heat-treatement process could be signficantly higher than that?  

Is heat cycling really necessary?  I agree with Jerry when he says "The age-old break-in procedures in the links also shows me that there is a lack of confidence in their machine work".  Heat cycling may indeed be obsolete if one pays proper attention to detail, but not for the reason that MotoMan suggests.

[jcs003]

i was using duncans method in contrast to motomans as i am sure was assumed.  i also stated that tolerances play a significant role.  this is where superior machining technique and technology offer an advantage.  i am glad jerry and wilkin stated this.  it is very clear that motoman i talking out of school, as i pointed out.  it is a shame so many are following his method when he cant explain correctly why his method is superior.

john

[F-Red]

First and foremost, I would love to read a write up, from Jerry Hall. :sign0188: For me, I use what has consistently giving me great results, even not knowing why! My son's have assembled 2 strokes, for many friends. They never do heat cycles, fire it up and ride, (Not me) with no issues. These friends are also BROTHERS in the hood. And nobody can abuse a motor, like brothers in the hood! :fighting0010::quad::cower:

[jcs003]

this is the part that gets me from motoman:

"The biggest factor is that engine manufacturers now use a much finer honing pattern in the cylinders than they once did. This in turn changes the break-in requirements, because as you're about to learn, the window of opportunity for achieving an exceptional ring seal is much smaller with
newer engines than it was with the older "rough honed" engines."

i am aware that abrasives and super-abrasives come in different grain sizes but how would make any difference?  i cant seem to find any good technical papers on the subject.  i tried sunnen but nothing pertaining to the surface finish of honed bores and association with ring sealing.

john

[ledperformance]

If you overload the rings before they seat, the burning gas can blow by them, increasing the heat even more. Because the rings are transferring heat from the piston through the cylinder walls it is important that they make as much contact with the walls as possible. If the rings over heat they can twist and warp in the ring lands and never seal properly. A controlled amount of heat and pressure is required to help the parts burnish and work harden while still fitting properly. Once the work hardening and burnishing occurs these surfaces are harder than when the parts were manufactured. If they are fitting properly these parts will performance better and last longer.
The pistons need to go through heat cycles so the internal stress can relax and it can fit the bore. The skirt needs to burnish and work harden to the cylinder wall as well.
Having said all this I have had to assemble engines at the race track and run them with very little break in time. We got by with it and you can too. If you can take the time to break in and heat cycle your engine should make more power and last longer.
The engine will accept short bursts of full throttle, but always short shift. I don't believe that the engine at idle, does anything to break in the piston. The 1rst 30 -60 seconds at idle does help seat the rings with no chance of over heating.  If you put to much heat into the piston to soon the often warp. This will lock the wrist pip into the wrist pin boss. You see this on pistons that you have to drive the pin out of. This can be death on 4 strokes and is not good on two strokes. It can cause the piston to expand more front to back and contribute to seizures. This is more likely to happen with forged pistons.
This is my opinion. This is how I have been doing it.
I am looking forward to reading Mr. Halls break in procedure. It is interesting to see what other people with experience have observed.