Piston Ring Installation

Discussion in '2-Stroke Engines' started by Porkchop, Aug 28, 2009.

  1. Porkchop

    Porkchop Member

    Hi All !
    I have a brand new Grubee 50cc engine that I completely disassembled to replace all the bolts with high strength. When I removed the cylinder, both rings fell apart into 3 pieces each, and a loose ball bearing fell out as well. Might be a blessing in disguise that I took this engine apart before starting it. What's the proper procedure to install new rings ? Any secrets or is it just straight forward like any other engine ? Don't know where the ball bearing came from. Both bearing assemblies on the crank are O.K. and the one in the clucth actuator is intact as well. I guess maybe they threw in an extra one in case I ever needed it.
    Thanks for any and all replies !

    ..... PC .....

  2. Al.Fisherman

    Al.Fisherman Active Member


    Can't see how it would be any different then a VW piston, although we had a split ring compressor. I'm sure you will need a extra hand or two...ring in 3 pieces with a extra ball...I'm banging my head against the wall.
    Although it was good that you did, but why did you remove the piston from inside the jug?
    Last edited: Aug 28, 2009
  3. Porkchop

    Porkchop Member

    I'm not concerned on how to get the rings in the cylinder. I'm concerned on how to get them on the piston. I assume a standard ring spreader. I have 2 sets of rings on the way. I hope I don't have to use the 2nd set if you know what I mean ! I'm looking for some tricks, do's or dont's from some of the more experienced engine builders here. I don't won't to destroy a brand new engine !
  4. mattysids

    mattysids Member

    well on my engine the rings did not fall apart!

    i have no idea where the bearings came from....

    but standard ring spreaders will do fine for you, i have replaced rings with simply my hands and pliers!
  5. srdavo

    srdavo Active Member

  6. Porkchop

    Porkchop Member

    srdavo, Thanks !!!!! That's something that might have gotten overlooked. That's the kind of reply that makes me glad I asked ! I'm going downstairs in a minute, will take a close look at my piston.
    Again, Thanks !

    ..... PC .....
  7. Bryan Smith

    Bryan Smith Member

    I have the Grubee 50 cc engine as well. My clutch bearing race was working its way off and I had to tack weld it back together. otherwise I would be seeing bearings coming out. These are very small about 3mm I'd guess and around 50 or so to a bearing.


    Ive had my jug off before and you should be able to slide the rings over the piston and squeeze the rings together enough with your fingers to get them started into the cylinder. be mindful of those alignment pins though.
    Last edited: Aug 30, 2009
  8. Porkchop

    Porkchop Member

    Thanks Bryan. I've already been warned about those pins. I'm still concerned about getting the rings on the piston. I have shopped the web for small ring expanders with no luck. You know somebody's got them. Lawn equipment repair shops have to use them. I'll shop localy tomorrow. I think my new parts for my engine are supposed to be here Tuesday. I looked at the photo link you also posted. I remember seeing your bike on another post. I like your kill switch and key idea. I have a handle bar mounted kill switch on my friction drive. I had already planned to replace it with a toggle sometime in the near future. How do you take apart the clutch assembly to get to thos bearings should I ever need or want to do that. Mine dosen't feel like it has any bearings in it. And what about the clutch pads ? How do you replace them and what holds them in place ? If you know the answers to these questions, I'd sure appreciate hearing/reading them.
    Attached are a couple of photos of the bike I'm working on. 1972 Schwinn Collegiate 5 speed, all original and in great shape.

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