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Weisco piston rings and end gap.

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This is my first time measuring ring end gap and Im running into a little confusion. I do not know weather to use OEM or weisco specs for ring end gap, and exactly how to measure the gaps.

 

First problem:

The spec sheet that came with the weisco kit gave a ring end gap much larger than the oem's spec. Weisco's spec is about the oem's service limit...

 

Weisco specs:

First ring - inches of bore X .005"

Second ring - inches of bore X .0053"

So with a 4" bore this comes to:

First ring = .02"

Second ring = .0212"

 

OEM ring end gap for 83 XL600:

first / second ring - .008" - .0016"

service limit - .02"

 

Second problem:

Weisco instructions (which if I had to guess I would go with them,) say to make the second ring slightly larger to prevent 'ring flutter.' My feeler guages have a range on them that is greater than the .0012" difference between the rings. For example one guage says .01" - .012" So it has a range on it of .02" when I want to detect a .0012" difference. The next guage up is from .013" - .015". If you take the average value, the feeler guages increase .00299" at a time.

.00299" is over double the .0012" difference I want in the two rings. I have 3 sets of feeler guages and they are all about the same. So are my guages just not accurate enough? or do I just need a lesdon in using them?

 

 

 

 

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weisco is famous for supplying rings with a piston that simply put have a LARGE gap , most guys that want to run the hard soon after the build go woth 4 thou per inch of bore, writing side or punch mark or symbol side up on the instalation. less gap on the second ring sometimes because the first takes most of the heat and expands more. when in doubt go with the piston manufacturers recomendations.

round off your feeler gauge readings , as long as your past the minimum spesc be happy

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I would already be running them.  A little extra ring gap never hurt anybody and the Wiseco's are usually on the large side.

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3 hours ago, turbo dan said:

I would already be running them.  A little extra ring gap never hurt anybody and the Wiseco 's are usually on the large side.

Always on the large side.  I've been using Wiseco pistons since the early 70s and never ever had to file a ring.  Just make double sure your bore job is proper, don't forget the Wisecos are forged and expand more than cast.  Use a reputable and knowledgeable machinist.

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17 hours ago, cjjeepercreeper said:

Always on the large side.  I've been using Wiseco pistons since the early 70s and never ever had to file a ring.  Just make double sure your bore job is proper, don't forget the Wisecos are forged and expand more than cast.  Use a reputable and knowledgeable machinist.

Modern high-silicon forged pistons do not expand significantly more than cast. The only real issue is that they expand SLIGHTLY faster than cast, which is irrelevant if you warm your engine up completely before riding. The expansion difference is so negligible that Wiseco Racers Choice pistons actually run tighter tolerances than OEM cast pistons.

Edited by The Spanky
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4 hours ago, The Spanky said:

Modern high-silicon forged pistons do not expand significantly more than cast. The only real issue is that they expand SLIGHTLY faster than cast, which is irrelevant if you warm your engine up completely before riding. The expansion difference is so negligible that Wiseco Racers Choice pistons actually run tighter tolerances than OEM cast pistons.

It's still important you have a machinist that knows what they're doing. I had a cylinder nearly destroyed a few years back.

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4 hours ago, The Spanky said:

Modern high-silicon forged pistons do not expand significantly more than cast. The only real issue is that they expand SLIGHTLY faster than cast, which is irrelevant if you warm your engine up completely before riding. The expansion difference is so negligible that Wiseco Racers Choice pistons actually run tighter tolerances than OEM cast pistons.

I run it just long enough to feel heat on the radiator through my glove.  Same thing I do with a cast piston.  Just that warm and its ready to open up.

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11 minutes ago, cjjeepercreeper said:

It's still important you have a machinist that knows what they're doing. I had a cylinder nearly destroyed a few years back.

Absolutely. If you're assembling an engine with improper clearances, tapered/out of round bore etc., don't be shocked when it grenades in an hour.

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Always on the large side.  I've been using Wiseco pistons since the early 70s and never ever had to file a ring.  Just make double sure your bore job is proper, don't forget the Wisecos are forged and expand more than cast.  Use a reputable and knowledgeable machinist.

I went to a very reputable machinist to get my cylinder bored. They checked piston clearances but did not check the rings. guess they expected me to do that. The rings came with a warning about the end gaps. It says that the rings are oversized and need to be filed. It gave a chart to determine proper gap based on how you will use it.

So based on your 40 years of installing wrisco rings, would you ignore this warning? I think I should file them to the weisco specs so I dont mess up the cylinder and piston.. but Im also worried about the gaps being too big, as that would put them past Honda's service limit. Just stuck here, dont know which way is right. Got thousands of dollars into this engine and I want my work to be perfect.

Thanks to everybody for your advice and opinions.

 

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22 minutes ago, madstories said:

I went to a very reputable machinist to get my cylinder bored. They checked piston clearances but did not check the rings. guess they expected me to do that. The rings came with a warning about the end gaps. It says that the rings are oversized and need to be filed. It gave a chart to determine proper gap based on how you will use it.

So based on your 40 years of installing wrisco rings, would you ignore this warning? I think I should file them to the weisco specs so I dont mess up the cylinder and piston.. but Im also worried about the gaps being too big, as that would put them past Honda 's service limit. Just stuck here, dont know which way is right. Got thousands of dollars into this engine and I want my work to be perfect.

Thanks to everybody for your advice and opinions.

 

Use Wiseco clearances for their rings. Their clearances are to ensure the rings don't hammer the locator pin out of the piston if it's a two-stroke. If it's a four-stroke you just have to be sure there isn't way too much gap or the will be blow-by.

I would put them in the bore and measure them, but most likely you won't have to do anything to them.

And I have to ask. You say you had the cylinder bored? What kind of bike is this? Most cylinders are plated and can't be bored without replating.

Edited by The Spanky

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They always say they need to be checked.  You checked them and they are on the large side.  This is not an issue since you know these rings are new.  The service limit is used to determine ring wear on a used top end.  If you set them up at the factory gap and you them judge how much wear has occurred later on by rechecking ring end gap.  If they have worn and grown from the original gap they have also lost tension and are in need of replacement.  Most likely though, if it ever comes apart again, it'll probably be for new rings or a whole new top end, so measuring and reusing the old rings is a non issue.

The ring gap in itself is not going to cause a problem unless it is grossly excessive.

Edited by turbo dan

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Use Wiseco clearances for their rings. Their clearances are to ensure the rings don't hammer the locator pin out of the piston if it's a two-stroke. If it's a four-stroke you just have to be sure there isn't way too much gap or the will be blow-by.
I would put them in the bore and measure them, but most likely you won't have to do anything to them.
And I have to ask. You say you had the cylinder bored? What kind of bike is this? Most cylinders are plated and can't be bored without replating.

It's an 83 XL600.
If I use the weisco specs the gaps will be past the OEM service limit. If I use OEM specs with my weisco rings, they might expand too much and butt together.
Im concerned about blowby if i use weisos specs because they are much bigger thsn hondas.
If I was going off Hondas specs, I would not touch the rings as they have a gap of .011 in the cylinder currently. (Honda recommends a .01" minimum on the gaps.) It looks like I have to file them... but still a bit unsure.

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58 minutes ago, madstories said:

I went to a very reputable machinist to get my cylinder bored. They checked piston clearances but did not check the rings. guess they expected me to do that. The rings came with a warning about the end gaps. It says that the rings are oversized and need to be filed. It gave a chart to determine proper gap based on how you will use it.

So based on your 40 years of installing wrisco rings, would you ignore this warning? I think I should file them to the weisco specs so I dont mess up the cylinder and piston.. but Im also worried about the gaps being too big, as that would put them past Honda 's service limit. Just stuck here, dont know which way is right. Got thousands of dollars into this engine and I want my work to be perfect.

Thanks to everybody for your advice and opinions.

 

If you do need to file them, which is unlikely, they are probably ceramic and require a special file so they don't chip.

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They always say they need to be checked.  You checked them and they are on the large side.  This is not an issue since you know these rings are new.  The service limit is used to determine ring wear on a used top end.  If you set them up at the factory gap and you them judge how much wear has occurred later on by rechecking ring end gap.  If they have worn and grown from the original gap they have also lost tension and are in need of replacement.  Most likely though, if it ever comes apart again, it'll probably be for new rings or a whole new top end, so measuring and reusing the old rings is a non issue.
The ring gap in itself is not going to cause a problem unless it is grossly excessive.

I checked them and the gaps are on the SMALL side. Weiscos spec sheet calls for the gaps to be made larger, and says the rings are supplied oversized, (meaning the gap is undersized)
After measuring the gap, I know it is within Hondas specs. If I file the rings to weiscos specs, then they will be past Hondas service limit. But If I keep the rings as they are, Im worried that the ends will butt together and cause damage. So is it ok to keep them as is?, or should I file them to weisco specs?

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I would call Wiseco to get the tie breaker.  Or err on the side of caution and run them to the large spec.  Leakage past a very slightly oversize end gap is going to be a negligible difference.

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As I said, use Wiseco's specs for their products. If you were installing OEM Honda rings, you would use their specs. But you're not.

 

Would you bore the cylinder to the proper clearances for a Honda OEM piston and then install a Wiseco? No, you'd use the Wiseco specs for the Wiseco piston.

 

Use the Wiseco specs.

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I would call Wiseco to get the tie breaker.  Or err on the side of caution and run them to the large spec.  Leakage past a very slightly oversize end gap is going to be a negligible difference.

Yes you are right. better too big than too small. I just want everything to be 100% proper. Would you consider a gap which is past the service limit to be only slightly oversized? This is my dilemma.
Calling weisco is a great idea, something I would have done if it wasn't the Easter long weekend. I guess I'm just going to have to wait and do that.

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As I said, use Wiseco's specs for their products. If you were installing OEM Honda rings, you would use their specs. But you're not.
 
Would you bore the cylinder to the proper clearances for a Honda OEM piston and then install a Wiseco? No, you'd use the Wiseco specs for the Wiseco piston.
 
Use the Wiseco specs.



OK I think I got this now.
So I guess weisco rings just expand more than hondas, which is why a larger gap is nedded. Running operating temp, it would have about the same gap as a set of honda rings also running at operating temp. So use weisco specs for their rings.
Is this correct?

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If you do need to file them, which is unlikely, they are probably ceramic and require a special file so they don't chip.

I guess Im the lucky one who must file his rings... I think u are right though that it is unusual, judging by the responses here. But if I go from their own spec sheet, the gaps are half what they should be.

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20 minutes ago, madstories said:

 

 


OK I think I got this now.
So I guess weisco rings just expand more than hondas, which is why a larger gap is nedded. Running operating temp, it would have about the same gap as a set of honda rings also running at operating temp. So use weisco specs for their rings.
Is this correct?

 

 

Something you're not taking into account, the Honda specs are for the stock bore size. Yours isn't. Larger bore means longer rings means more expansion.

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