1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

commando 750 piston

Discussion in 'Wanted' started by ninja, Feb 12, 2019.

  1. ninja

    ninja

    Joined:
    Oct 10, 2017
    hi
    has anyone got a +20 Hepolite piston for my 750 commando.
     
  2. grandpaul

    grandpaul VIP MEMBER

    Joined:
    Jan 15, 2008
    Just one piston, or a set? I might have a set, but they're used. If I remember right, they have the large oil hole with slot, but NOT the continuous slots across the back and front.
     
  3. kommando

    kommando

    Joined:
    May 7, 2005
    I have 2 used ones, with slots but not continuous, tops have some dings possibly from a bad decoke by a gorilla. You can have them for postage.
     
  4. ninja

    ninja

    Joined:
    Oct 10, 2017
    Hi thanks for that I haven't had the bike long and had a rattle, stripped her and left piston had picked up so got my buddy at the machine shop to check it over and apparently its been underbored he says a good thrash would have wrecked her,anyway right piston is good and measures up ok so lucky I think how much postage friend.
     
  5. ninja

    ninja

    Joined:
    Oct 10, 2017
    Oh regarding slots whats the relevance? cheers
     
  6. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    The slotted pistons were known to fail, ie lose their tops due to fracturing in the lower ring groove where the slot is located.

    My 750 had them (+ 0.020" )
    If the bore on your bike is still good (in spec with a hone) it might be more prudent to pick up a set of new +0.020" JCC pistons, they are not much more than US$100 a set and you get the good Hastings rings.
     
    Last edited: Feb 13, 2019
  7. ninja

    ninja

    Joined:
    Oct 10, 2017
    cheers for that.
     
  8. kommando

    kommando

    Joined:
    May 7, 2005
    The continuous slots are an issue, they only needed a short crack to appear and then the top of the piston to depart from the body and it happened a lot. They changed them to short slots and the issue was resolved but some people confuse the 2 types and avoid all slots. I have new JCC pistons to replace mine and for see no issues with them, have NOS Hepolite rings and also good circlips to replace the suspect JCC ones.
     

Share This Page