1982 CB750F...Better Devil

irk miller

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Jimbonaut said:
Could you elaborate Irk on "inch of bore"?
My Chevy sbc 350 engine has a 4.00" bore, so minimum ring gap is .016". I gap at .018". The 823 is 65mm pistons, which is 2.56" bore, so .010". I would gap to .012". Here's the chart from Wiseco:

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf
 

Jimbonaut

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Thanks for the help Irk - you'd gap to 0.12", would that be for the top or bottom ring? Sorry to be a drag but would you mind telling me what gap for the top ring and what gap for the bottom? Much appreciated mate.
 

Jimbonaut

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Also, to arrive at .010" are you referencing the "Dirt/ATV/Snow/PWC" application on the Wiseco table you sent me?
 

irk miller

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I would go the high performance street/strip number to get .012". Just do the math. 65mm = 2.67" which is 65/25.4. Then multiply that number x .045 for the top ring and .055 for the second ring. For most stock applications the number is .04 and .05.
 

Jimbonaut

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Right on man, thanks for bearing with me, maths is not my strong point. So, to confirm, going with the High Performance Street numbers, 0.012" for the top ring gap and 0.014" for the lower ring gap, right?
 

Jimbonaut

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Cheers mate, that’s a huge help. I’m working on them now, one more question. The top ring has a slight bevel on the outside face, whereas the lower ring doesn’t, and has a slight slanted face, right?


Sent from my iPhone using DO THE TON
 

irk miller

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Jimbonaut said:
Cheers mate, that’s a huge help. I’m working on them now, one more question. The top ring has a slight bevel on the outside face, whereas the lower ring doesn’t, and has a slight slanted face, right?


Sent from my iPhone using DO THE TON
Usually, the top ring is chrome/brighter on it's edge while the second ring is usually black or darker. The beveled ring is usually the second ring and the bevel faces down as an oil scraper. The top compression ring usually doesn't have a bevel.
 

Jimbonaut

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My rings have the same profile as these -



and so the silver-edged, double bevelled ring went on top with the slightly sloped-egded black ring went on the bottom -



To file the edges of the rings I clamped the file into a vise, rather than clamping the ring itself -

 

doc_rot

Oh the usual... I bowl, I drive around...
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usually a diamond grinding wheel is used. make sure you debur the edge of the ring after sizing.
 

Jimbonaut

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Cheers Doc, duly noted - made sure all the edges were burr-free but can't hurt to double check
 

Jimbonaut

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Ok. A Bad Thing happened.

Got the pistons/rings installed...



Didn't have an extra pair of hands around so made do with some zip ties around the outside studs -



- tight enough to hold the cylinder in place where I needed it but not too tight that I couldn't slide them down the studs when needed. Worked pretty well. Got #2 and 3 into their cylinders -



and was a couple of mms and an oil ring away from installing #1 and 4 -



when I realized that the chain tensioner assembly was jammed up against the case -



No bother, backed the cylinder up a cm or so, tucked the tensioner inside the case and that's when disaster struck. Realized that the reason the tensioner wasn't slotting into the case was because I'd tightened up the two nuts on the thing. Loosened them up and that's when one of the copper washers behind the nuts took a dive into the engine. You can see it - pre disaster - next to my finger in the above photo. Haunting me.

Fished around with a magnet but no joy. I'm pretty sure I know the answer to this but is there anything I can do before splitting the cases to find the fucking thing?

One mm away. One mm.
 

doc_rot

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You can usually get at it through the oil pan
 

Jimbonaut

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Realized that copper is not magnetic so that's that plan down the shitter - maybe me and a mate can move the lump around enough to dislodge it and get at it from the oil pan. I'm not very optimistic, but surprisingly at peace with the whole thing. I have no idea why.
 

adventurco

Nick Ol' Eye
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Just run it, copper is soft I'm sure the transmission gears will grind it into a dust no problem ;D
 

doc_rot

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KZ1000s have these tiny rubber blocks that need to be installed in the cam chain tunnel. super easy to drop in. I have done it more than once and each time i was able to get to it via the oil pan.
 

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