Subject: Re: [TR] Ring gaps

From: David Porter <[email-masked]>
Date: Fri, 12 Feb 2016 15:11:26 -0700

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   0.004 per inch of bore..
           DaveP

On 2/12/2016 2:02 PM, Andrew Uprichard wrote:
>
> The manual for the TR3 says the ring gap should be 0.003 – 0.010.  But 
> I have new pistons and rings marked that the gap should be 0.003 – 
> 0.004 per inch diameter of the bore.  3 thou sounds awfully tight to 
> me, but what do others think?
>
> On a related subject, a friend has an engine where the ring gap is 
> 0.040.  How much of this could be made up by simply replacing the 
> rings?  Or is there a point at which the only solution is bigger 
> pistons +/- rebore?orter Porter Custom Bicycles 2909 Arno St. NE 
> Albuquerque, NM 87107 505-352-1378 Go HERE: my world www.porterbikes.com/
>

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      0.004 per inch of bore..<br>
              DaveP<br>
    <br>
    <div class="moz-cite-prefix">On 2/12/2016 2:02 PM, Andrew Uprichard
      wrote:<br>
    </div>
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        <p class="MsoNormal">The manual for the TR3 says the ring gap
          should be 0.003 – 0.010.  But I have new pistons and rings
          marked that the gap should be 0.003 – 0.004 per inch diameter
          of the bore.  3 thou sounds awfully tight to me, but what do
          others think?<o:p></o:p></p>
        <p class="MsoNormal"><o:p> </o:p></p>
        <p class="MsoNormal">On a related subject, a friend has an
          engine where the ring gap is 0.040.  How much of this could be
          made up by simply replacing the rings?  Or is there a point at
          which the only solution is bigger pistons +/- rebore?orter
          Porter Custom Bicycles
          2909 Arno St. NE
          Albuquerque, NM 87107
          505-352-1378
          Go HERE: my world <a class="moz-txt-link-abbreviated" href="http://www.porterbikes.com/">www.porterbikes.com/</a>
        </p>
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** [email-masked] **

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From: "Alex&Janet Thomson" <[email-masked]>
Date: Fri, 12 Feb 2016 17:38:00 -0500

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In the first case, those two sets of measurements seem to agree on the upper
end - 0.003 x 3.250 = 0.00975.  But a total of just 0.003" does seem quite
snug.

On the related topic, the question is where does the wear exist? Is it in
the cylinder or in the ring. You can always use a telescoping gauge and
micrometer to see what the bore actually is. And/or. if you can obtain a
sleeve of rings for just one cylinder, install a compression ring by itself,
square it to the hole at several locations, and see what you have for ring
end gap. Since those are sleeved engines, you could also purchase
piston/sleeve kits but that gets expensive. I have found that on tractor
engines where someone has installed aftermarket piston/sleeve big bore kits,
it may be difficult to find replacement rings for those pistons. What does a
compression test tell you on that engine?

Alex Thomson

From: Triumphs [mailto:[email-masked]] On Behalf Of Andrew
Uprichard
Sent: Friday, February 12, 2016 4:02 PM
To: [email-masked]
Subject: [TR] Ring gaps

The manual for the TR3 says the ring gap should be 0.003 - 0.010.  But I
have new pistons and rings marked that the gap should be 0.003 - 0.004 per
inch diameter of the bore.  3 thou sounds awfully tight to me, but what do
others think?

On a related subject, a friend has an engine where the ring gap is 0.040.
How much of this could be made up by simply replacing the rings?  Or is
there a point at which the only solution is bigger pistons +/- rebore?

Andrew Uprichard

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vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span =
style=3D'color:#1F497D'>In the first case, those two sets of =
measurements seem to agree on the upper end &#8211; 0.003 x 3.250 =3D =
0.00975.&nbsp; But a total of just 0.003&#8221; does seem quite =
snug.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'color:#1F497D'><o:p>&nbsp;</o:p></span></p><p =
class=3DMsoNormal><span style=3D'color:#1F497D'>On the related topic, =
the question is where does the wear exist? Is it in the cylinder or in =
the ring. You can always use a telescoping gauge and micrometer to see =
what the bore actually is. And/or. if you can obtain a sleeve of rings =
for just one cylinder, install a compression ring by itself, square it =
to the hole at several locations, and see what you have for ring end =
gap. Since those are sleeved engines, you could also purchase =
piston/sleeve kits but that gets expensive. I have found that on tractor =
engines where someone has installed aftermarket piston/sleeve big bore =
kits, it may be difficult to find replacement rings for those pistons. =
What does a compression test tell you on that =
engine?<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'color:#1F497D'><o:p>&nbsp;</o:p></span></p><p =
class=3DMsoNormal><span style=3D'color:#1F497D'>Alex =
Thomson<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'color:#1F497D'><o:p>&nbsp;</o:p></span></p><div><div =
style=3D'border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in =
0in 0in'><p class=3DMsoNormal><b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span>=
</b><span style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> =
Triumphs [mailto:[email-masked]] <b>On Behalf Of =
</b>Andrew Uprichard<br><b>Sent:</b> Friday, February 12, 2016 4:02 =
PM<br><b>To:</b> [email-masked]<br><b>Subject:</b> [TR] Ring =
gaps<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>The manual =
for the TR3 says the ring gap should be 0.003 &#8211; 0.010.&nbsp; But I =
have new pistons and rings marked that the gap should be 0.003 &#8211; =
0.004 per inch diameter of the bore.&nbsp; 3 thou sounds awfully tight =
to me, but what do others think?<o:p></o:p></p><p =
class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>On a related =
subject, a friend has an engine where the ring gap is 0.040.&nbsp; How =
much of this could be made up by simply replacing the rings?&nbsp; Or is =
there a point at which the only solution is bigger pistons +/- =
rebore?<br><br>Andrew Uprichard<o:p></o:p></p></div></body></html>
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From: Tony Drews <[email-masked]>
Date: Fri, 12 Feb 2016 20:39:19 -0600

I had to go to 0.017 for the top ring, Grant 
rings, 87 mm pistons in a race motor.  Less than 
that and I broke rings.  0.014 for the middle 
ring.  Used to run less with Deves rings.  You 
may need a little less on the street, but it's 
mainly a function of how hot things get.  A few 
thou too much is way, way better than one thou too little.

For your friend, 0.040 is a lot of end gap, 
something is worn more than I'd be comfortable 
with.  Have to measure things to figure out where the wear is.

Tony Drews

At 03:02 PM 2/12/2016, Andrew Uprichard wrote:
>Content-Type: multipart/alternative;
>         boundary="----=_NextPart_000_00A5_01D165AE.C8E327E0"
>Content-Language: en-us
>
>The manual for the TR3 says the ring gap should 
>be 0.003 – 0.010.  But I have new pistons and 
>rings marked that the gap should be 0.003 – 
>0.004 per inch diameter of the bore.  3 thou 
>sounds awfully tight to me, but what do others think?
>
>On a related subject, a friend has an engine 
>where the ring gap is 0.040.  How much of this 
>could be made up by simply replacing the 
>rings?  Or is there a point at which the only 
>solution is bigger pistons +/- rebore?
>
>Andrew Uprichard
>
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