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Piston Ring Compressors

johnod

Forum Mentor
Past Site Supporter
What do you guys use for ring compressors?
Bought 2 sets from ebay but not convinced they are any good.
My good one too big of course.
 
When I rebuilt mine and the times I helped Steve, we just used our fingers to push them in while sliding the head down slowly
 
When I rebuilt mine and the times I helped Steve, we just used our fingers to push them in while sliding the head down slowly

And make sure there's a good lead-in taper in the bottom of the bores....

As an aside, I find on modern nicasil bores where the barrel is in one piece with the top case and the pistons have to be fed in from the top, It's best to make up a bolt on plate for the top deck with the lead-in taper in that...The current very thin rings - esp oil rings - do not like ring compressors at all.
 
I use strips of plastic from yoghurt tubs with a hose clamp outside.
Plastic seems to let the rings into the flare easier.
Centre pots first then the outer two.
 
Yep, fingers.

It's best to have four hands available, so it really helps to be a circus freak and/or have a reliable helper. It's possible to do with only two hands, just a lot harder.

I've tried hose clamps and a couple of different types of ring compressor tools, and none have proven useful.
 
Fingers for me and if the going gets tough a couple of popsicle sticks to poke with.
 
Hose clamps tightened just enough to get the rings into the taper. Then VERY gently tap on the cylinders. Be gentle, patient and very observant.
 
To each their own and I am a novice but the hose clamps worked very easy for me. Just had them tight enough to hold the rings in place while lowering the jugs over them. And if I can do it, anyone can.
 
To each their own and I am a novice but the hose clamps worked very easy for me. Just had them tight enough to hold the rings in place while lowering the jugs over them. And if I can do it, anyone can.

That's how I did it. Set one pair of pistons to TDC and get them into the cylinders. I thought it was easier when the rods were vertical. Be careful rotating the crank to the next pair, everything will want to fall down when the first pair leave TDC. Maybe suspend the head from the frame with a ratchet strap. The second pair will be pushing a bit sideways, but you'll have some notion of what to expect getting them in after the first pair.

Either way, it's definitely fiddly and frustrating. Take enough time, and walk away before you break a ring, or tear a gasket or something.
 
I just put together the top end of my 550 last night. No clamps needed but definitely would have been easier with a second set of hands!
 
I haven't done this often but I'm with the fingers-folk. But with fingers..., well,
...ONE THING I would try next time is to put lots of "strike-up marks" on the rings and piston with a felt pen that face me as I juggle the head down slowly.. I know a little bit isn't crucial but it bugged me at the time when I was trying to check if the ring-gaps were oriented to their angles
 
I haven't done this often but I'm with the fingers-folk. But with fingers..., well,
...ONE THING I would try next time is to put lots of "strike-up marks" on the rings and piston with a felt pen that face me as I juggle the head down slowly.. I know a little bit isn't crucial but it bugged me at the time when I was trying to check if the ring-gaps were oriented to their angles

Rings rotate in use, so alignment of the gaps isn't crucial.
 
Rings rotate in use, so alignment of the gaps isn't crucial.
Interesting-I was wondering about that because there's no little pin in the groove like two-strokes have...I guess putting them in at varying places starts them off so they stay generally staggered anyways...? and I've been told that even if the gaps are inline (occassionally?) it won't make much difference when the rpm is 1000+ or so.
 
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