Actual engine break-in data

Discussion in 'The Perfect Line and Other Riding Myths' started by Drop_Center, Nov 15, 2018.

  1. Drop_Center

    Drop_Center Long timer

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    I don't know who couldn't be convinced after watching this it doesn't really matter what you do, just ride it.

    #1
  2. ozmoses

    ozmoses .

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    Not surprised.
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  3. TrashCan

    TrashCan Scary Jerry

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    The warranty goes from idle all the way to the throttle stop.

    Most manufacturers leave a lot of power untapped for this reason.
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  4. Itinifni

    Itinifni n00b

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    I wish he had elaborated on the "only measurable difference was in the ring gap" (4:22 of the vid). That's exactly what I would expect due to the high cylinder pressures of WOT acting on new rings in a fresh cross-hatch.
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  5. Macgyver007

    Macgyver007 Adventurer

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    I noticed that too. That would be the first place I would expect to show a measurable difference and it sounds like there in fact was one. even though he said they were "in spec", it sounds like there was a noticeably bigger gap but he didn't say how much. I don't worry much about break in procedures but I think one of the parts that makes sense to me is seating the rings but he kinda just glossed over that part.
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  6. ozmoses

    ozmoses .

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    As he said, the info is in the video description:


    Engine 1, “By The Book Break-In” Installed at 1,828 miles, removed at 2,861 miles Break-In Notes: Ridden gently. Didn’t exceed 50% throttle or 5,000 rpm for the first 600 miles, and didn’t exceed 75% throttle or 7,000 rpm until 1,000 miles. Didn’t experience WOT until 1,000 miles was accumulated. Ridden with constantly varying engine speed and load, no easy task on a slow bike in a busy, urban environment! Oil and filter changed at 600 miles. Piston OD: 2.9910” at install, 2.9910” after 1,000 miles Cylinder ID: 2.9925” at install, 2.9930” after 1,000 miles Top Ring End Gap: 0.0130” at install, 0.0145” after 1,000 miles Compression: 235 psi hot after 1,000 miles Leak Down: 4% hot after 1,000 miles


    Engine 2, “Brutal Break-In” Installed at 2,861 miles, removed at 3,890 miles Break-In Notes: Went to WOT within moments of first starting up, and was ridden hard for 1,000 miles. Did everything we’re told not to—lots of throttle and high-speed droning at steady throttle. Oil and filter changed at 600 miles. Piston OD: 2.9910” at install, 2.9910” after 1,000 miles Cylinder ID: 2.9925” at install, 2.9930” after 1,000 miles Top Ring End Gap: 0.0130” at install, 0.0150” after 1,000 miles Compression: 235 psi hot after 1,000 miles Leak Down: 4% hot after 1,000 miles





    Not much end gap difference.
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  7. C/1/509

    C/1/509 Now with more sarcasm

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    Interesting and as has been said, not especially surprising. Queue up the "Yeah, but..."
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  8. Macgyver007

    Macgyver007 Adventurer

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    Thats about what I would expect, I would have guessed about a 25% difference in ring wear and I suspect that most of that happened within the first few dozen miles and leveled off. I usually take it easy for the first couple tanks of gas after a rebuild. Not so much to "break in" as much as just to make sure there are no issues or noises before going all out. The resilience and durability of piston rings always amaze me. Those little buggers are in a pretty harsh environment. I still don't see myself redlining a fresh rebuild or new motor within the first hundred miles but its nice to see some actual data.
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  9. PAULIBIKER

    PAULIBIKER Been here awhile

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    :eek2Hit by a firework and it broke his jaw?!
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  10. sieg

    sieg Wearing out tires......2 at a time, day after day. Supporter

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    Don't surprise me at all, back in the 70's I'd build an engine on Friday night and drag race it on Saturday.

    And still today my break in is, break it in like your gona drive it.
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  11. Paebr332

    Paebr332 Good news everyone!

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    0.0005" difference? My first thought is it is more likely measurement variation than part-to-part variation. Also, it looks like the set of gauges was probably one with leaves that vary by 0.0005" so the true difference could be as small as a single tenth.

    I won't go total quality system nerd here and point out that a single sample at each treatment is not enough to draw any meaningful conclusion. No, I will not do it.

    :hide
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  12. AzB

    AzB Fattest thin man

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    As someone who has a great deal of experience with mass produced motors, this is something that everyone on the business has known for years. Decades even. With the increases in accuracy of machining and assembly, along with much better consistency, tolerances can be set to a stable "middle ground" that provides reasonable reliability and longevity. Are there even any manufacturers that require a real break in procedure any more?

    And as someone that has built race and hi performance street motors, I'll also add that custom built motors that are required to run stronger than stock while also retaining much of the same reliability are going to require tighter tolerances. And I will always recommend a strict break in procedure for best results on any motor built by me.
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  13. Richarde1605

    Richarde1605 Long timer

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    To me most of this 'break in procedure' is cya. Most motorcycles these days get a full power run on a dyno at the factory, how can I stuff it up whatever I do? It was flogged by the factory before I even got it, and having predelivered bikes before, I cannot say that I didn't rev the mv f4 but others did much more than me.
    Then again I have seen high mileage engines break top rings because they had been babied for their whole life and then someone gives them a rev and breaks the top ring on the lip...




    Sent from my SM-G950F using Tapatalk
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  14. markk53

    markk53 jack of all trades...

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    Worn rings, if showing that wear within 1000 miles will be allowing oil to get by and burn by far sooner than the lesser worn rings allowed to seat in properly. That's what we saw back in the day with Z1s.

    That said, if you break in the bike like you will normally ride, most people will do fine since they don't live at red line. Drag racers seldom leave an engine built and racing for 5000 miles much less 25,000 miles, so that's how they get away with it.

    We always told people to just ride, don't red line, but rather stay around 20% under (say 1000-2000 rpm), don't lug the engine, and don't do continuous set rpm drones. That would be best in general.

    I think the reason for the "under 4000 rpm for 600 miles" stickers was a good buy on stickers back in 1970.




    Is Motortrend part of the Bonner group or is Henning off to a better thing. I do NOT like the new Cycle World or Motorcyclist format. Look at the success of Hot Rod, then emulate it in a motorcycle magazine along with the tests.
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  15. dtysdalx2

    dtysdalx2 PITA but useful

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    Hit by a cannonball more like. :eek7 Them is dangerus.

    I watched the vid too. No surprise I guess. But if the motor blows up within a year the mfg has to pay for it.
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  16. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Never saw a reason to red line any of my motors. Peak torque and HP both always live at an RPM below red line or rev-limiter.
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  17. markk53

    markk53 jack of all trades...

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    Yep. true red line as representing peak power, on many Japanese bikes, is 500-1000 rpm below the marking on the tachometers. Plus shifting at the actual torque peak is better than at the hp peak in many cases.
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  18. Richarde1605

    Richarde1605 Long timer

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    Many diesel vehicles have a green torque zone marked on the tacho
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  19. dtysdalx2

    dtysdalx2 PITA but useful

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  20. Richarde1605

    Richarde1605 Long timer

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