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wrist pin bushes - ok to reuse?

  • Tarvis
    Tarvis
    5 years ago
    Hey all,

    I'm in the process of reassembling my evo and I'm about to reassemble the pistons with the conrods.

    The wrist pin bushes have a small amount of chatter (see pictures), and I'm not sure if they are reusable. The wrist pins look fine and you can barely feel the pitting on the bushes. I am not certain whether I caused it when removing the pistons, entirely possible I suppose.


    I'm doing the bike up in my garage, and the motor is in the frame, so pressing new bearing shells in might be difficult. Obviously I'll do it if necessary though.

    Would be grateful for any advice.
    Cheers,
    Tarvis

    IMG_1177.JPG
    IMG_1178.JPG
  • paulybronco
    paulybronco
    5 years ago
    If it was my build i would replace them. Think as it as insurance because if it did let go you would be kicking yourself
  • Baloffski
    Baloffski
    5 years ago
    Quoting paulybronco on 08 Oct 2018 06:39 AM

    If it was my build i would replace them. Think as it as insurance because if it did let go you would be kicking yourself

    Not a mechanics arseole friend , but definately smalll expensive, for some piece of mind.With Paul.
  • John.R
    John.R
    5 years ago
    I didnt bother. Mine felt and looked golden. And it was an 85 or 86 motor.
    How do the new pistons gudgeon rings feel in there?
  • paulybronco
    paulybronco
    5 years ago
    Quoting John.R on 08 Oct 2018 07:36 AM

    I didnt bother. Mine felt and looked golden. And it was an 85 or 86 motor.

    How do the new pistons gudgeon rings feel in there?

    These ones dont look that golden to me...
  • John.R
    John.R
    5 years ago
    Quoting John.R on 08 Oct 2018 07:36 AM

    I didnt bother. Mine felt and looked golden. And it was an 85 or 86 motor.

    How do the new pistons gudgeon rings feel in there?

    Quoting paulybronco on 08 Oct 2018 07:59 AM

    These ones dont look that golden to me...

    True, was on phone couldn't make put anything but blur and a rod, but I see whats happening now.
  • paulybronco
    paulybronco
    5 years ago
    Quoting John.R on 08 Oct 2018 07:36 AM

    I didnt bother. Mine felt and looked golden. And it was an 85 or 86 motor.

    How do the new pistons gudgeon rings feel in there?

    Quoting paulybronco on 08 Oct 2018 07:59 AM

    These ones dont look that golden to me...

    Quoting John.R on 08 Oct 2018 08:29 AM

    True, was on phone couldn't make put anything but blur and a rod, but I see whats happening now.

    Thought that may be the case.....definite wear on the bush.
  • Tarvis
    Tarvis
    5 years ago
    Thanks all, appreciate the comments.

    Think I'll change them up, thanks for convincing me not to be lazy.

    Not sure how I'll go doing this in the garage, but will give it a crack.


  • Baloffski
    Baloffski
    5 years ago
    Good on ya T man. Give it a go. I love doing shit, fuckup then do it again.. But do it once take the time and do whatever properly, is good.
  • speedzter
    speedzter
    5 years ago
    This is not a job for a home mechanic unfortunately.
    The bushes that are in there are likely far better than anything you can fit with the crankshaft in the bike.
    Removal and fitting would be easy enough, but they need to be reamed first and then honed to a very fine tolerance.
    This is probably one of the most important clearances to get right in an engine.
    I suggest your better off running what you have, or at least get the clearance measured with a snap gauge .
    The tools aren't cheap either.

    Pin fiment specs:





    pin fit.JPG
  • brucefxdl
    brucefxdl
    5 years ago
    Quoting speedzter on 08 Oct 2018 10:21 AM

    This is not a job for a home mechanic unfortunately.
    The bushes that are in there are likely far better than anything you can fit with the crankshaft in the bike.
    Removal and fitting would be easy enough, but they need to be reamed first and then honed to a very fine tolerance.
    This is probably one of the most important clearances to get right in an engine.
    I suggest your better off running what you have, or at least get the clearance measured with a snap gauge .
    The tools aren't cheap either.

    Pin fiment specs:





    pin fit.JPG
    speedzter is on the money,very few if any gudgeon [wrist pin ] bushes that dont need reaming and finishing to size,the process is an art in it self.
  • Tarvis
    Tarvis
    5 years ago
    Could you have them reamed, honed and fitted to the wrist pins off the bike (disassembled) and then the bushes pressed in?

    You've given me a bit to think about there, will need to mull this over.
  • brucefxdl
    brucefxdl
    5 years ago
    Quoting Tarvis on 08 Oct 2018 11:17 AMedited: 08 Oct 2018 11:19 AM

    Could you have them reamed, honed and fitted to the wrist pins off the bike (disassembled) and then the bushes pressed in?

    You've given me a bit to think about there, will need to mull this over.

    the bushes must be reamed /finshed in place[ in the rod].suggest you try and get a reputable/reliable engine builder to come and measure the bushes and give an opinion of what to do or take it[in a trailor] to some one you know/trust.the process usually involves a machine that guides the rod to make sure the bush bore remains parallel to the crank pin bore while it is honed.cheers
  • daddyracer56
    daddyracer56
    5 years ago
    its normally done when da rods are out & crank rebuild 
    was a bit ruff getting them out by da look of it , would fine clean the hit marks & check with a new wrist pin see how it feels , tilt etc . or measure proper , but when removing the piston  you need to chock the rod with a wedged wood so you don't hurt the big end bearing or bend the rod , also heat the piston 1st removing & installing, check to see if wrist pin get jammed were c'clips go or c-clips groves' are worn , bottom end maybe needing looking @ , also check wrist pin or rod tilt with deck of case before moving forward

  • Tarvis
    Tarvis
    5 years ago
    No update on this yet. Hoping to speak to an engineer that we know today who does up old bikes.
    I will also chat to the folks I've been buying parts from and see if they can advise on it, or direct me towards a shop that can do this in motor.

    I have had a look at the jim's tool and the conrod holder that they sell also, which is designed to allow the bush to be cut when the rods are in the motor. Its not clear to me how the conrod holder they sell helps ensure that the reamer cuts true - other than to minimise the conrod moving while you're doing it. I'm considering going down this path and fabricating my own conrod holder. I've got the shop manual for this bike and it gives the procedure for doing this repair while the rods are in the motor. The Jim's tool is going to come near $400 Aussie landed - so I guess that's the upper limit of getting someone else to do the work.

    Agree that this would be 100% easier with the crank out of the motor. Its a bugger as I've got access to a mill that could do it too in that case.


  • Tarvis
    Tarvis
    5 years ago
    Ok, small update on this.
    Speaking to two lots of people yesterday (one engineer, one HD specialist), they suggested trying to use what is there provided there is no interference with the operation of the wrist pins.

    The front wrist pin bush seems fine taking this approach, I will need to have a closer look at the rear bush as it is slightly snug going in.

    If i decided to go in the other direction (as others here have suggested), and pull down the motor and get the crank out to be done properly by a shop, what at a minimum should I be looking to replace when rebuilding? Obviously bottom end gaskets and seals all around, but what about bearings etc.? Appreciate this may all depend on wear, but would be keen to understand the minimum requirements so I can work out the time and cost of me doing it. Motor is a 92 Evo just in case i hadn't mentioned that previously. I've also got access to a press.

    Thanks for all the advice thus far.

  • daddyracer56
    daddyracer56
    5 years ago
    i have a tool for checking the conrod straightness , its just a longer than wristpin machined up tool that you can slide it in da little end & bring it da conrod to near bottom deade centre & with a feeler gauge determine exactly how straight your little end or rod is , i would not replace bushes unless necessarily a must , , those little notche's are nothing if cleaned up proper , you would have to measure the inside dia of the pin & the outside out the new wrist pin clearance is max 0015"to 0002" cheers Bob
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