Piston ring question now :(

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baldock
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Piston ring question now :(

Beitrag von baldock »

sorry for all of these questions. I had hoped the new manuals would stop this constant pestering for information :(

The piston/rings are NOS + 0.50
One manual states that the top ring is marked 'T' and another manual says 'N'. Both say that the middle ring is tapered.
One of my rings is silver and the other is black. They both have 'T' and '50' on either side of the gap. Neither say 'N' and I cant see any taper.
Can anyone advise which one goes where?

The manuals also say that I need to put the rings inside the bore first and check the gap, but they only state what it should be for a standard size ring (Top/second 0.30-0.50mm, oil side rail 0.2-0.9mm).
Is it the same for all rings or is there a different gap for +0.50 ?

Thanks
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Zuletzt geändert von baldock am 15. September 2021, 16:23, insgesamt 2-mal geändert.
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hiha
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Re: Piston ring question now :(

Beitrag von hiha »

Usually the black ring is the tapered one, but the taper is only a few minutes, and not visible. (I can see it on your foto, although its out of focus ;-) )
Control the ring gap, that's important.
http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf
And insert rings with inscription upside.
Cheers,
Hans
baldock
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Re: Piston ring question now :(

Beitrag von baldock »

Thanks for the reply about the ring positions,

so my only concern now is the ring gap.

I've been reading up on it and it seems like I need to find the gap given by the manufacturer (Honda) as wiseco could be different as it is specific to their product/materials.

Obviously I have no way of doing that so if anyone can answer that question I'd be very grateful and the build can continue.
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Gunnar_HH
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Re: Piston ring question now :(

Beitrag von Gunnar_HH »

Hello Baldock,

On your gap question, it's simple. The rings must fit the piston and the larger cylinder.
When you put in the second extension, the rings must also be for the second extension.

The calculation shows:
Circumference at 89mm is 279.46mm
Circumference at 89.5mm is 281.03mm
This makes a difference of 1.57mm
So, small rings in the big cylinder is not so smart.

Use the appropriate rings and the clearance should be a maximum of 0.50mm.

Cheers Gunnar
XL500R / Bj 82
Moto 6.5 / Bj 96
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baldock
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Re: Piston ring question now :(

Beitrag von baldock »

I rang the engineer who did the rebore and he said that the ring gap stays the same regardless of the oversize piston. Its just the rings that are fractionally larger to match the larger piston/bore. He said that's why the manufacturer only states one set of figures, and a set of NOS rings normally come manufactured within the upper/lower limit.
I don't know if he's correct or not, but I checked the ring gap of my new .50 rings and they did fall within the overall limit in the manual.

MANUAL
TOP 0.30-0.50mm
MIDDLE 0.30-0.50mm
OIL (SIDE RAIL) #1 0.20-0.90mm
OIL (SIDE RAIL) #2 0.20-0.90mm

MY 0.50 RING SET
TOP 0.49mm
MIDDLE 0.48mm
OIL (SIDE RAIL) #1 0.75mm
OIL (SIDE RAIL) #2 0.55mm
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