Smaller rings on a piston

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Justin Taylor

Justin Taylor

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I have a lil red barn 460 popup piston and they Machine there rings to be 1.4 mm thick. Stock size is 1.2mm, I have a pair of caber 1.2mm rings will this be a problem?
 
huskihl

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Measured with my calipers there 1.4
How big does the slot in the piston measure? Also, measure your new rings. I’m just wondering if your caliper is off or wasn’t zeroed.

Never heard of 1.4 mm rings. Doesn’t seem cost effective to have their own special rings made, vs buying a Chinese set for 50¢
 
Justin Taylor

Justin Taylor

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How big does the slot in the piston measure? Also, measure your new rings. I’m just wondering if your caliper is off or wasn’t zeroed.

Never heard of 1.4 mm rings. Doesn’t seem cost effective to have their own special rings made, vs buying a Chinese set for 50¢
Piston was 1.5mm new caber rings were 1.2 and lil red barns rings were 1.4 it dosent make sense to me
 
huskihl

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Piston was 1.5mm new caber rings were 1.2 and lil red barns rings were 1.4 it dosent make sense to me
You need 1.5 mm rings then. There is only about .001 - .003” clearance for the rings. I’m guessing that LRB rings are just slightly undersized. Look for a set of caber rings for the diameter and thickness you need, rather than by saw model, as most aftermarket pistons use 1.5 mm rings where OEM might be 1.2 MM
 
Justin Taylor

Justin Taylor

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You need 1.5 mm rings then. There is only about .001 - .003” clearance for the rings. I’m guessing that LRB rings are just slightly undersized. Look for a set of caber rings for the diameter and thickness you need, rather than by saw model, as most aftermarket pistons use 1.5 mm rings where OEM might be 1.2 MM
I’m going to double check my measurements with a real pair of calipers then I will probably order the 1.5mm rings. Thanks for the great info
 
drf255

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It’s common for AM pistons to use a different ring than oem. They could be 1.4 or 1.5 but, regardless, don’t use the 1.2mm Cabers on that slug.

I ruined a freshly ported 036 jug that way once. The dot matrix “S” symbol I thought I saw on top of the piston was actually a “G” for Golf. Bad way to learn a lesson. I put standard 1.2 mm Cabers in the slug, not realizing they were loosey goosey. Lasted 2 cuts and saw dies. Lots of carnage.
 
Justin Taylor

Justin Taylor

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It’s common for AM pistons to use a different ring than oem. They could be 1.4 or 1.5 but, regardless, don’t use the 1.2mm Cabers on that slug.

I ruined a freshly ported 036 jug that way once. The dot matrix “S” symbol I thought I saw on top of the piston was actually a “G” for Golf. Bad way to learn a lesson. I put standard 1.2 mm Cabers in the slug, not realizing they were loosey goosey. Lasted 2 cuts and saw dies. Lots of carnage.
i think I’ll probably be safe just using there rings since it’s what it came with but I am not using the 1.2mm thanks
 
Mad Professor
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It’s common for AM pistons to use a different ring than oem. They could be 1.4 or 1.5 but, regardless, don’t use the 1.2mm Cabers on that slug.

I ruined a freshly ported 036 jug that way once. The dot matrix “S” symbol I thought I saw on top of the piston was actually a “G” for Golf. Bad way to learn a lesson. I put standard 1.2 mm Cabers in the slug, not realizing they were loosey goosey. Lasted 2 cuts and saw dies. Lots of carnage.

I hear you.

But, 1.2 or 1.5 mm rings. Never seen a 1.4mm, but never used any Chi-Com stuff either.

LilRed Barn used to handle Italian Tecomec, good parts.

But Tecomec went Chi-Com. I talked with Tilston-Total US distributor, who was the importer. They were all disgusted with the path of Tecomec...

Just my two cents about: rings, Tecomec, Chi-Choms,...........

Old good Stihl stuff was "A" or "B" based on tolerances. Replacement pistons then were "A/B" , a compromise. Slap a little but won't seize up......
 
LegDeLimber

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If you have any doubts about the calipers, try measuring a few things that you feel you know what the dimensions are.
Feeler/thickness gauges that aren't bent or damaged where you can't use them for this task.
Many of us have them on hand!

How about a good grade of drill bit? As long as the shank hasn't been spun in the drill chuck, that kinda screws up the roundness and true diameter etc.
 
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