How To: Break in an engine

[GPracer2500]

My comment/question is about the difference between heat treatment and heat cycling. In the context of this discussion, I believe there is a difference. Heat treatment is a process of material hardening that occurs at the time of manufacture (quenching being a popular method). But heat cycling is a process of stress-relief. A piston has a lot of internal stress created by the forging process. The metal is literally beaten into shape and this has profound effects on the grain structure of the metal. Internal stress is created and cycles of heating and cooling releive that stress. I don't believe that the heat treatment that occurs during manufacture addresses stress-relief.

It should be noted that this only matters with forged pistons. Cast pistons (such as most stock pistons) do not require stress-relief (by nature of their uniform grain structure) and therefore don't require any heat cycles. Forged vs. cast pisons make a difference in how an engine should be broken in.

I'll save my thoughts on ring seating for another time...

Comments?

[plkmonster2]

Well, I have my thoughts too. Motoman may have proven his ways, but I have proven my own. I have broken in 4 higher performance engines in my time. These included my 225DR 200E (Yamahas) my 110 ATC and my 400EX. I did the 400 and the 225 first. They were the halfway baby type, 1/4-1/2, then 1/4-3/4, etc for about one hour of run time. My 200E and the 110 were doen the motoman way, after I read about the article. Lets just say the 110 is not running. I didn't rev it up, or floor it, just gave it a lot of gas, and under a load. The rings gave up in 6 months. They started to smoke bad, and I started to loose compression.. Fast. One day it just stopped idling. About a week later, the chain broke, and shattered the case. I opened the motor up about a year ago. I found the two compression rings shattered, and in about 15 pieces apiece. They had hit the head, scored the walls, and RUINED the piston. The ring gaps had fused together. No wonder it didn't run! As for my 200e, I rebuilt it 2 years ago. it was my dad's, and the sparkplug was left out during wintwer for some reason. It pitted the cylinder. I got a barely used cylinder and piston, and rebuilt it with new rings, and a fresh hone. Did it again the motoman way. It had run "good" to this day. About 2 weeks ago it has started to smoke until it is warm.... I think It's time the tear it apart and do it again... the right way. Just letting you guys know this.. My 225 has run 5 or 6 years without a problem. Compression has not dropped, and it does not burn oil. Same with my 400ex.. Odd if you think of it.

[gixer_boy99]

This is kind of a touchy subject I guess..... But think of this! How do top fuel dragsters break in the motors??? I know its kinda different but think about it if the motor is going to blow then it willl right off the bat... So thats why I think break it in like how its going to be rode... I do ran my bike in the garage for just a bit to break in the cam then I took it out and ran it hard for a little bit then I came back and changed my oil.. Then I changed it again after a tank of gas.....

[GoldenGloves]

I have a simple theory.. Some may agree, some may disagree...

Now I'm sure that most of us on this board, dont baby our bikes all of the time, there is one point or another we're hauling ***.. So, basically...

You want to break in your engine to the best potential availible...

So the best way to break in your engine, is to to suit your riding..

If you plan on driving around the track or dunes like your Girlfriend or wife, baby that Quad when your first ride after you buy it or after your rebuild it, so the rings dont seal properly and arent adjusted to high speeds..

If you plan on driving around the track or dunes like a madman out of hell, ride your bike like you want it to be rode, adjust those rings to your type of riding, now I'm not saying start it out and first and bounce off the rev limiter in every gear, but be somewhat aggressive with it, to suit your type of riding...

If you baby it, they wont seal properly at first, they will be thinking, "okay he wants us to go slow, so we're sealed slow"

If you take it somewhat aggressive they will be thinking "damn, this guy likes this throttle, we have to be sealed to go fast"...

The best example I can give while being drunk..

[beerock]

dragster motors are built with special rings and tolerances that are tighter, and the newer tehcnology motors dont need to be broken in at all, but were talking about motorcycle motors not new car motors which have HIGH END technology and tolerances on the new motors are so much tighter with the new tehcnology that breaking in is a thing of the past.

its not so on motorcycle/quad 2 stroke or 4 stroke off road motors, not even the newer technology 450's

[JJ69]

i dont know about 2 strokes.. but i bought a 2002 honda fourtrax 350, 2wd, i jumped it off the back ramp of the honda dealer and ripped her up the tracks wide open. i later adjusted the valves after a few hours, then i put a pipe/jet kit on it, but it was too loud, so i took off the pipe but left it jetted. I have had the bike since late '02 and have never had to touch the engine, and it works better than any 350 fourtrax i've seen stock.

when you first break in a bike, if you dont go past half throttle, then it is going to start wearing the cylinder only so far, when you really come on to it, it'll make it work harder and the bike will be worked in to your style of riding.
if your gonna take it easy on the bike forever, then keep er easy. if you plan to burn the piss out of it, then do so asap.

[JJ69]

Originally posted by Yellow400guy
this is all fine and good if u are rebuilding ur engine urself, but what about those who buy one brand new, and the dealership has doged em pullin in and out, and i konow this happens cus ive seen it. not even warming em up jsut start and give it hell.

I agree.. a friend of mine went on a job-shadowing experience at a Honda dealer, they let him ride all the bikes to put them away at closing, the dealership is just in front of some tracks, three or four of the guys after work just rip the bikes wide open down the tracks and then put them away. i'd rather them do it this way anyway, so anything thats gonna break from factory, is gonna break before i buy it.

[beerock]

Originally posted by JJ69
i dont know about 2 strokes.. but i bought a 2002 honda fourtrax 350, 2wd, i jumped it off the back ramp of the honda dealer and ripped her up the tracks wide open. i later adjusted the valves after a few hours, then i put a pipe/jet kit on it, but it was too loud, so i took off the pipe but left it jetted. I have had the bike since late '02 and have never had to touch the engine, and it works better than any 350 fourtrax i've seen stock.

when you first break in a bike, if you dont go past half throttle, then it is going to start wearing the cylinder only so far, when you really come on to it, it'll make it work harder and the bike will be worked in to your style of riding.
if your gonna take it easy on the bike forever, then keep er easy. if you plan to burn the piss out of it, then do so asap.

I call BS cuz if you took the pipe off and left it jetted it would run like crap or at least foul plugs

[JJ69]

no sir, it runs like a top.
it doesnt foul plugs.. i was told after i inquired about leaving it in that all it would do is run rich, and have no real long term troubles.. and its true.

[beerock]

sounds like a good shop, let the bike run rich so you can foul plugs, leave carbon deposits on top of the head and ultimately need to be rebuilt sooner then later....