Best way to remove piston from rod?

Discussion in 'Engine' started by Luni, Jun 1, 2011.

  1. Luni

    Luni Member

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    Im rebuilding my top end on my blaster. I had my stator side crank seal fail and create an air leak which resulted in me running lean and detonating/melting a piston.

    Im sending my jug and head off to be ported, bored, honed, and a proper sized piston ordered for it, but I need to get my piston off my rod.

    Ive never done this before, so before I start screwing with it, Im just wondering the best tool/method for getting that piston off.

    If it helps, its a Wiesco.

    BTW, I did a search, and all I could really find was a vague reference to using needle nose pliers.
  2. specialized7

    specialized7 Can't Stop, Won't Stop!

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    Thats pretty much it use those needle nose pliers to pull the clips holding the wrist pin together then a small tube will push out and the piston will be free from the connecting rod
  3. Luni

    Luni Member

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    Im not seeing where the needle nose pliers will pull anything though. Ill go futz around with it tomorrow and see what I can do.
  4. bagds101

    bagds101 New Member

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    heres what i did since i was replacing everything anyways. 1. take a jewelers flat screwdriver. 2. pop the clips out by prying on them one part at a time until you can slide the screwdriver in there to finish taking it out. 3. push the rod out from the side that the clip is still in using the flat screwdriver and slight tapping with a hammer. 4. the piston comes off. repeat steps 1-4 in the opposite order when youre installing your new piston. youre done. be careful with it and take your time. you dont need a clip falling into your bottom end like i did. luckily i had a magnet that i got it out with. also, install the clips straight up or straight down. never sideways. ken oconnor has a how to video on putting a top end together. it is EXTREMELY helpful imo
  5. Paulie B

    Paulie B New Member

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    I pull both clips out using a jewelers flat head like above (you can't re-use them anyway) Then drive the pin out with a 3/8 socket extension.
    Be sure to fully support the piston with your hand to put zero stress on the big end bearings.
    If you don't believe that you can't re-use the clips I seen one of my alcohol weedwacker motors fail from dropping an old clip I re-used.
    Don't chance it.
  6. Luni

    Luni Member

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    Ok. Thx Paulie and everyone else for the help. Ill get it figured out.
  7. Larry's Shee

    Larry's Shee Member

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    Stuff a clean rag/towel around crankcase opening to prevent anything from falling into bottom end. If pin is stuck in piston do not beat on it. Make a pinpuller using threaded rod , socket smaller than pin and deepwell socket larger than pin. My ONLY experience with re-using circlips decades ago was not a pretty sight.
  8. Luni

    Luni Member

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    I wont reuse a circlip. My piston is fried. I need a new one and the kits come with the new circlips so thats not a problem.

    Thanks for the advice.
  9. bagds101

    bagds101 New Member

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    i would replace everything but the connecting rod man. just to be safe. piston, pin, circlips, bearing, rings.... theyre all cheap if they dont come with the kit.
  10. Luni

    Luni Member

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    They do come with the kit though (all but the bearings) and I already planned on replacing it all.
  11. alex90

    alex90 New Member

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    the topend bearings are included with the wiescos
  12. NEONNIGHT34609

    NEONNIGHT34609 New Member

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    this is the way i do it. DONT beat on the piston or the pin you will stress the other end of the rod ( on the crank side ) and that will lead to major issues.
  13. Luni

    Luni Member

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    I got it off. I was able to use a precision flathead screwdriver to extract the circlips, then I was able to use my finger and just push the piece through. Was easier than I thought.

    Hopefully the new circlips are as easy to get in as they were to get out.
  14. bagds101

    bagds101 New Member

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    for me they werent. i actually dropped one of my new ones in my top end when i went to put them back in. used a magnet to extract it and got it out. then i called ken oconnor so he could walk me through it on the phone. but be careful not to bend the clips when youre putting them in. they are not hard to do.
  15. sicivicdude

    sicivicdude New Member

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    ^^^^ why you stuff a clean shop rag down into the crankcase BEFORE trying to install the c-clips LOL!

    I have a process I put the c-clips in with. The cutout for clip installation/removal is usually 45 degress from level with the piston top. Considering that the opening of the c-clip is supposed to be pointed straight up or straight down, that means that the cutout is either somewhere near the end no matter which direction you install the c-clip. Wiseco's cutouts are pointed upwards so I install the c-clip opening downwards. I stick one end of the c-clip into the groove on the side opposite the cutout and then use a pair of needle nose pliers to push the cutout side of the c-clip in. I have gotten quite good at judging the where to grab the c-clip so the tips end up in the cutout. Once you've got the clip into the piston, use a flat blade screwdriver to push it down into the groove (if part of the clip didn't seat into the groove during installation). If the clip went too far into the hole (past the groove) use the wrist pin to push it back until it seats.

    Do one circlip out away from the engine (good for practice too) and then install the pin through the other side. Put a clean shop towel into the crankcase opening and install the other circlip once the piston is slid over top of the rod with the wrist pin through it.
  16. 370

    370 New Member

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    paulies on the right track. what works really well is an AWL or small shop pic. but a tiny flathead works well too. pop out the clip and a 3/8 extension works really well for pushing a stubborn pin out. try to avoid beating on that extension. you'll probably find that you can get the pin loose by hand. the pin puller is a good idea. youi'll need soem small threaded rod thought to get through a socket that small. i'm not a fan of hittign teh extension because your transfering that pressure to the lower bearing.

    don't skimp when your buying parts. replace the wrist pin bearing too. it's a $7 part when it goes back together make sure to check the ring end gap, piston to wall clearance, and once it's assembled leak down test that engine to make sure you don't have a leaker.
  17. 370

    370 New Member

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    your real problem is the crank seal though. have you fixed that issue? 99% of the time i replace the bearing behind a failed seal. not just air sneaks through em. but if your just gonna put a seal in smear a very thin coating of yamabond on the outside edge of the seal and find a socket or piece of PVC that fits outter diameter of the seal and give it taps in a crisscross pattern it'll seat nicely that way
  18. DirtDiggler

    DirtDiggler DUNEFREEK

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    My 2 cents to go with this is during re-assembly is give all your parts a good coat of 2 stroke oil , the wrist pin bearing , the wrist pin , the piston and cylinder , you don't want a dry start on a new top end , that could end things prematurly , or at the very least cause some friction damage that could shorten the life of your new top end .
  19. Luni

    Luni Member

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    Im gonna assemble my engine the way Ken O'Connor shows in his video. Cleaning the cylinder with Dawn and a paper towel the way he does, coating everything with 2 stroke oil the way he does, everything per the video.

    As for the seal, I havent changed it yet, but I will change it before I start it.

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