Cylinder coatings

Discussion in 'Mechanic and Repair' started by zmelli, Oct 13, 2012.

  1. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,126

    in a service manual for one of their engines i rebuilt awhile back
     
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Not sure I'd want somebody thats had so many bad experiences with Kohler engines rebuiling one for me.....especially if he had to look up any thing more than torque specs or tolerances in the manual....
    Probably let you build a Kawasaki though...anybody can build one of those...

    BTW..Kohler explicitely discourages crosshatching (deglazing) nickle silicone bore engines...The way I looked at it was...somebody crosshatched the engine when it was new...so if I found the right tools...I could do it too....and I'm still doing it....
     
  3. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,126

    yeah i had to look up step by step how to take the motor apart. and then figure out what all those parts were.

    a flex hone is perfectly acceptable to use on a nikasil cylinder, why kohler doesnt recommend that is beyond me. personally I think it is crucial to getting a good ring seal
     
  4. cgaengineer

    cgaengineer LawnSite Fanatic
    Posts: 15,782

    I think you are correct...they can also be reamed and a cast iron sleeve inserted.
     
  5. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,126

    sleeving is probably the cheaper route to go, i looked into both once but its been so long i can't remember which was the better deal
     
  6. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    $100 doesn't go to far at the machine shop anymore....
     
  7. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,126

    probably not worth it at all for one of these motors, I am referring to dirtbikes, and especially high performance 2 strokes. life expectancy of piston/rings isn't long at all and the jetting is usually run on the ragged edge of too lean. it's not unheard of to rebuild em every season. theres a couple companies that make sleeves for them and a few places as well that run cylinder exchange programs, send em the bad one they send you a fresh resleeved one. given the volume they do it's not that expensive, definitely alot cheaper than a brand new cylinder.
     
  8. cgaengineer

    cgaengineer LawnSite Fanatic
    Posts: 15,782

    The bottom ends don't last long either...it's really great when the bottom end needle bearing make there way through transfer ports and inside the cylinder of a freshly rebuilt top end.
    Posted via Mobile Device
     
  9. kawakx125

    kawakx125 LawnSite Bronze Member
    Posts: 1,126

    I never did have any bottom end problems, but after taking a dip in a nice mudhole 3 miles from the truck one day that was the end of that top end :). funny thing was bike started right up and ran the rest of the day but fouled 3 or 4 plugs and seemed a little down on power. Got home tore it apart and found out i'd actually seized the motor. must have ingested some water and washed off the oil on the intake side of the cylinder. luckily the majority of it was just aluminum from piston scraped off onto cylinder wall, and some acid and very fine sandpaper took care of it. minor scratches in the cylinder wall but went ahead and rebuilt it anyway and it ran like a top, still is to this day i believe
     
  10. zmelli

    zmelli LawnSite Member
    Posts: 57

    You know all the above could have be prevented with Amsoil!

    Ok now that was a joke. so you have a choice, chrome lined with cast iron rings, or cast iron with chrome rings. seems like the trimmers are made with the chrome/irom rings. I wonder how the Honda GX-25 is put together? cast iron or chrome rings? This makes me want to go 4-stroke for longivity.
     

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