Dang piston rings... help! peugeot 103

I broke three rings last night trying to get my piston into the cylinder. ARRRGGH! Now I have to wait several days until moped warehouse sends me some new rings. (I still have 1 good ring left on the piston.)

Anyone have advice on getting the piston to slide into the cylinder more easily? I tried wrapping a thin piece of cardboard around the piston to compress the rings, but it didn't seem to help much.

At first I was trying to do this with the piston connected to the connecting rod. I got frustrated with this and took the piston off, and broke my second to last of 4 rings trying to get the piston in from the bottom of the cylinder.

Does anyone have tricks or just plain advice for me? I was about ready to throw the damn thing across the garage last night. Should I try from the other side of the cylinder? I have to take the pin all the way out to do this.



Dang piston rings... help! peugeot 103

Something is wrong.

You did line the ends of the rings up with the locator pins didn't you ?

There is NO WAY.. you should break them with the piston OFF the rod ... they should go in easy in that case.

It should be easy to compress the rings with your fingers in that case.

Dang piston rings... help! peugeot 103

If you didn't know -

The ring end locator pins are in the ring grooves.

Re: Dang piston rings... help! peugeot 103

Thanks, Fred. I will look at it tonight, but I won't be able to give it another try until I get some new rings from the moped junkyard.

I didn't know about the ring locators, thanks. When I used to do this on my volkswagen, I had a ring compression tool that let me get the clyinder sleeves around the pistons fairly easily.

BTW, thanks to Lenny for the new frame! The old one was in awful shape.


Re: Dang piston rings... help! peugeot 103

david f martin /

Also, when you find the locater pins, note whether they are in the middle of the groove or not. Your rings may be cut in a "V" shape, to accomodate the locating pin on one side of the groove or the other.

Soak the piston and rings in oil for a little while and coat the inside and edges of the cylinder with oil before you install the piston and rings. Holding the rings in place, gently rotate the cylinder back and forth (very small turns, like 1/8") while working it on.

If you encounter any resistance, back up immediately and start over again.

Once you have the rings in the cylinder, you should be able to slide the piston up and down in the cylinder with just a very mild, smooth resistance. If it doesn't feel like that, take it off and start over.

Just don't get in a hurry. That's how you break stuff.


Pinch grooves ?

I dunno exactly if that's what they are called, but on the bottom of Tomos cylinders there's two slots that are very useful in that you can continue to compress the rings with your fingers as you slide the piston up into the cylinder.

If your 103 has something similar, it might help your method to make use of it.

Although it didn't work out so well with this, kudos to you for takin the advice and buyin double rings before starting, now go buy four more.

You can NEVER have too many piston rings.


Re: Dang piston rings... help! peugeot 103

Thanks, everyone.

I was unaware of the locator pins in the ring grooves before this thread, which probably explained why I broke three rings trying to force my piston into the cylinder. I found them last night. Quite obvious, if you know that they exist. I guess I never even thought they'd be there; if i remember right, my VW never had anything of the sort.

AFAIK, there isn't any direction do the puegeot rings. I looked real closely and they looked symmetrical, so I think that I can install themeither way.

There are grooves in the bottom of the cylinder, but I'm not sure if I will be able to use them to compress the rings, as they aren't located in the same spot as the locator pins.

Thanks for all your help. I'll report back when I get my new rings from the junkyard and try this again.


Dang that was easy!

Man, I got the piston in on the first try. It was pretty easy once I knew about the locator pins. After this, it took about 10 minutes to assemble the engine (not countnig the 1/2 hour i spent looking for the wasehr I dropped on the gruond...)

Thanks guys! All I need now is some of those metal end thingies that go on the throttle and choke cables and I should be good to go. I will check a bike store around here to see if they have any.


Re: Dang that was easy!

Garelli_teen /

I had the same problem looking for those cable ends, but I found some at NAPA auto parts store!

Re: Dang piston rings... help! peugeot 103

I am in the same predicament......so the ball pein hammer and pliers to compress the rings were not the right option?!!!!....I am a jackaz....this post was extremely helpful!

Now to find 4 new rings.....

Re: Dang that was easy!

yeah auto parts stores have them, usually come in variety pack with at least two small enough for moped use.

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