• 2 stroke Engine Break in and what you need to know.

    Article and write up by Dennis Mears / Flotek Performance.
    In this article I'm going to discuss engine break-in .what it is why it's needed and the proper way of doing it . There are several methods people have used, this is only one and my preference that I prefer to use. Engine break-in is basically a procedure to allow for the thermal expansion of the rings and cylinder wall to wear in the moving parts to themselves to obtain a good bore seal. This is critical to the performance and longevity of the engine . Assuming all the Assembly is complete and all the proper testing has been done, you can begin the break-in process. It is a good idea to start with fat jetting (specifically a larger than Normal main jet ) and work your way down. The main jet is the real circuit to be concerned with. Be sure to use the same oil premix ratio you would've typically always use. I'd recommend 32-1 and good castor based oils such as Klotz or Maxima .Its important to be sure all nuts are torqued down to spec. Basically this is a process of repeated heat cycles followed by running the machine on a light load for short periods of time to promote the thermal expansion were looking for . Keep the bike in neutral after a short run at Idle to a quarter throttle for several minutes, now it's time to shut it down .I like to do this three or four times over the course of a day, allow 15 minutes or so to cool all the way so the pipe is near room temperature. I like to put a fan aimed at the cylinder especially for a air cooled engine during the cool down process. Once that is complete you can take the bike for a leisurely rides but never holding the Throttle wide-open or doing extended high RPM runs for too long you want to gradually increase the load and rpms as you do this. Its now a good idea to check what the plug or plugs look like as far as jetting. You want to look for a cardboard color on the porcelain with a 2mm tall ring inside. Also it's a good idea to re-torque the head and base nuts just in case they worked loose .Many people baby their bikes during this time and their bikes don't last as long and never really run right to their potential in my opinion. It really doesn't take a long time to do this and its unnecessary to burn several gallons of gas through. In my experience one tank of leisurely riding should be more than enough gradually getting higher rpm's and running it at higher speeds for longer times it's better to just ride it hard as you always do and don't baby it .You want heat and wear to occur not a glazing effect on the bore. At this point you can ride it as you always do and continue to monitor engine temperature jetting for good measure and peace of mind. Do a plug chop to confirm jetting and that everything looks OK. Dennis Mears
    Comments 22 Comments
    1. Paulie B's Avatar
      Paulie B -
      Great write up Dennis
    1. John Tice's Avatar
      John Tice -
      Hi Dennis: Will you please explain this, I don't get it?
      You want heat and wear to occur not a glazing effect on the bore.
      Seems like the new Brush hones instead of the Ball hones do a beautiful
      Plateau type of finishing job which helps finish up the Break In period?
      Thank you
      JT
    1. Slider's Avatar
      Slider -
      This is the best explanaton I've seen in some time.
    1. HondaATC's Avatar
      HondaATC -
      I've always been taught to assemble the cylinder/rings dry in order to prevent glazing. I NEVER do that to bearings though.
    1. StrokeitTwice443's Avatar
      StrokeitTwice443 -
      Quote Originally Posted by HondaATC View Post
      I've always been taught to assemble the cylinder/rings dry in order to prevent glazing. I NEVER do that to bearings though.
      is this meening that you dont use an assemby lube on the cylinder walls when putting a motor back together? i always pour some premix onto a rag and wipe the cylinder walls down with a thin coat myself.

      good artical Denny. really helps the noobs understand why it's important. thanx for takin the time to do this. now, explaining the differance in break in for a steel sleeve and a Nikasil coated one would help folks even more.
    1. John Tice's Avatar
      John Tice -
      I'm not trying to be picky, just educating people who are unfamiliar with cylinders. All cylinder liners (Sleeves) are about a class 40 grey Cast iron composition. Weather Spun cast investment or any kind of pour. The hardness can vary greatly depending on the kind of heat treating which was used.
      Steel is never used in cylinder liner composition.

      Photos of a load of cylinder castings that I had poured at a couple of local Cast Iron foundries in the Portland area. My company relined hundreds of cylinders before I sold out in the later 80ís.
      Iím now retired and enjoying the business again on a limited basis.

      We went through a load like this around every 3 months or so. There is a interesting history of the Cycle cylinder liner business. I might do a write up on it if enough of you show some interest?
      Hobbits Hole
      JT
    1. Paulie B's Avatar
      Paulie B -
      I think it would be crazy to assemble them dry.
    1. Paulie B's Avatar
      Paulie B -
      Quote Originally Posted by StrokeitTwice443 View Post
      is this meening that you dont use an assemby lube on the cylinder walls when putting a motor back together? i always pour some premix onto a rag and wipe the cylinder walls down with a thin coat myself.

      good artical Denny. really helps the noobs understand why it's important. thanx for takin the time to do this. now, explaining the differance in break in for a steel sleeve and a Nikasil coated one would help folks even more.
      I would be very interested in knowing a good way to break in a Nikasil jug- since I'll be doing that soon.
      It's my first
    1. HondaATC's Avatar
      HondaATC -
      Quote Originally Posted by StrokeitTwice443 View Post
      is this meening that you dont use an assemby lube on the cylinder walls when putting a motor back together? i always pour some premix onto a rag and wipe the cylinder walls down with a thin coat myself.

      Yeah, that's just the way I've always done it. The reason it was explained to me was that basically if it didn't come out of the fuel mixture naturally, that it would be too much on the cylinder walls and as the engine heated up and fired it would start to actually burn it on the sides and make a glaze. Could be wrong and I'm open to other ideas, but it sorta made sense to me and thats basically the way I've always done it. Main and rod bearings always get a generous coating of oil though. I lightly grease the wrist pin bearing as well.
    1. HondaATC's Avatar
      HondaATC -
      Quote Originally Posted by John Tice View Post
      I'm not trying to be picky, just educating people who are unfamiliar with cylinders. All cylinder liners (Sleeves) are about a class 40 grey Cast iron composition. Weather Spun cast investment or any kind of pour. The hardness can vary greatly depending on the kind of heat treating which was used.
      Steel is never used in cylinder liner composition.

      Photos of a load of cylinder castings that I had poured at a couple of local Cast Iron foundries in the Portland area. My company relined hundreds of cylinders before I sold out in the later 80ís.
      Iím now retired and enjoying the business again on a limited basis.

      We went through a load like this around every 3 months or so. There is a interesting history of the Cycle cylinder liner business. I might do a write up on it if enough of you show some interest?
      Hobbits Hole
      JT
      John, a long the same lines of the cylinder hardness discussion we had recently, any ideas on difference/scale of hardness between a sleeve and the rings? I'm sure the rings are harder but I'm kinda curious how much. Aren't most rings hard chromed? That might be a good contribution to this discussion as well to learn how the two parts wear and break in together.
    1. StrokeitTwice443's Avatar
      StrokeitTwice443 -
      Quote Originally Posted by HondaATC View Post
      Yeah, that's just the way I've always done it. The reason it was explained to me was that basically if it didn't come out of the fuel mixture naturally, that it would be too much on the cylinder walls and as the engine heated up and fired it would start to actually burn it on the sides and make a glaze. Could be wrong and I'm open to other ideas, but it sorta made sense to me and thats basically the way I've always done it. Main and rod bearings always get a generous coating of oil though. I lightly grease the wrist pin bearing as well.
      thats interesting to me. i just think that when the rings are new, thats when they are the most sharp on the edge and should be able to clean the excess off before glazing starts. im going to say that the process is, or can be debatable according to personal preferance and experiance.
    1. John Tice's Avatar
      John Tice -
      Quote Originally Posted by HondaATC View Post
      John, a long the same lines of the cylinder hardness discussion we had recently, any ideas on difference/scale of hardness between a sleeve and the rings? I'm sure the rings are harder but I'm kinda curious how much. Aren't most rings hard chromed? That might be a good contribution to this discussion as well to learn how the two parts wear and break in together.
      I just sent this email off to Wiesco & Wossner piston. We will see what happens. Back in the 70ís Wiseco pistons had some large problems to say the least. Their piston rings were Moly filled Cast Iron and snapped like Popcorn. As we all know at this time, Wiseco has cleaned things up and now is at the top. Email below




      Gentlemen: Iím glad that Iím starting to do business directly with the piston manufacturers so I can have a good repore with the technical department. We have a wonderful site that you gentlemen should be acquainted with. http://www.everything2stroke.com/con...comments_start. 23K members and growing. There is a rather active debate on breaking in a new piston & rings. Will you please through in your 2-bits worth to attempt to straighten all of this out.
      Thank You
      John Tice


      As to Billyís question: Rings are extremely hard with the Chrome Plating. Everyoneís sleeves are extremely soft, thatís why the break in period.
      Now days the majority of rings are Hard Chrome plated on some kind of spring steel. Maybe my email will help us all out on this controversy. In my education quest, we need evidence & proof rather than opinions, although experience in the end usually proves all.
      ďOld DogĒ
      JT
    1. mjm540ii's Avatar
      mjm540ii -
      John, have you received an email back from wiesco?
    1. John Tice's Avatar
      John Tice -
      Nothing yet, The Wiesco people are sorting through their email pile, I reminded them while on another subject.
      John at Wossner acknoweleged but is out of the country & will respond when returning.
      Sorry the spell checker doesn't work
      JT
    1. mjm540ii's Avatar
      mjm540ii -
      ,,,So if i want to run 40:1, but I have been running 32:1 during the actual break in, is this harmful?
    1. Wossner Pistons's Avatar
      Wossner Pistons -
      Hey guys John asked if I could stop by and say hello, I am short on time so what's the question as I see several and many of you and your experiences are going to be greater than mine with regards to specific two-stroke questions..Please send them to us at Wossner and our email is below..

      My our email is info@wossnerpistons.com

      Thank you,

      John Noonan

      Sales Manager

      Wossner Pistons USA.
    1. John Tice's Avatar
      John Tice -
      Hello Guys: John Noonan from Wossner Piston was kind enough to answer our email request. Will some of you please step up and ask him your break in questions.
      JT
    1. Wossner Pistons's Avatar
      Wossner Pistons -
      Well couldn't have been too much of a pressing matter as not one person replied or emailed.

      Take care,


      John
    1. FerrinMotorsports's Avatar
      Quote Originally Posted by Wossner Pistons View Post
      Well couldn't have been too much of a pressing matter as not one person replied or emailed.

      Take care,


      John
      I'll just jump in here and ask what do you recommend for break in procedures when installing a new piston and rings?
    1. John Tice's Avatar
      John Tice -
      Hi Ferrin: Please address your question to john@wossnerpistons.com.
      JT