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Bore gauge

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I’ve had a few cylinders over the years that I wasn’t sure needed to be bored, but out of an abundance of caution I always went ahead and had them bored oversized.

 

Currently I’m waiting on my machine shop to bore several cylinders for me, and one of my projects is on hold because he doesn’t get them done very quickly.

 

I have a cylinder for this project (2012 Rubicon) that came off of a “runs good, no smoke“ engine but I did not have any way to verify that before tearing it down

 

Cylinder actually looked pretty good so I thought rather than just shipping it off to have it bored, I would see if possibly a hone and set of rings might work.

 

So I bought a bore gauge, pictured.

 

The particular spacer that I used to get close to the 92mm bore was a 3.6” with a .02 shim.  I’m not sure exactly how that should turn out but with my calipers I got 3.633 with no pressure on the bore gauge.

 

Service limit on this Rubicon is 92mm-92.10mm

 

When I inserted the board gauge into the cylinder I got about .0010 on the bore gauge, which subtracted from 3.633 is 3.623, which is 92.02mm, so assuming that is consistent in taking several measurements, then I should be able to hone this cylinder with new rings.  
 

of course, taking several measurements will show whether the cylinder is out of round, and I will also have to measure the piston or get a new standard piston with rings.

 

does anyone here have any machining experience? Just making sure I am doing this correctly.

 

 

 

 

 

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I took several measurements and the variances were no more than .002. Out of round and taper service limits were both .004 so I should be good there as well

 

So now I just need to make sure that my piston is OK to use/ in spec and if so, order a new set of std rings and a top end gasket set.

 

This was off of a parts bike. According to prior owner, rear swingarm bolts backed out, wallowing out the threads, and the whole rear end came out from under the guy while he was riding. Most of the bike’s plastics diffs  etc. were gone, What I got was a frame with engine in it.

 

I’m always skeptical when I get a “ran good, no smoke” engine unless I can verify went buying.

 

I got this machine with plans to rebuild the engine or use it for parts, and traded for it so had little to lose if it was trashed. 
 

 

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I've never used a bore gauge but from what i have seen,  it is subjective. Finding the perfect halfway point seems to be difficult at first until you get the feel for it. The top measurement is extremely important for me because that is the factory bore with no wear. I am like you......when in doubt just bore it.. Just a few more bucks and the waiting time....ugh

Edited by Misterclean
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1 hour ago, Misterclean said:

I've never used a bore gauge but from what i have seen,  it is subjective. Finding the perfect halfway point seems to be difficult at first until you get the feel for it. The top measurement is extremely important for me because that is the factory bore with no wear. I am like you......when in doubt just bore it.. Just a few more bucks and the waiting time....ugh


Well I have two more Rubicon cylinders at the machine shop now, but it sometimes takes months for him to get to them, so since this one looked good visually, I measured it this morning and then I ordered a std set of rings and a gasket set.  I’ll hone this one and get it back together.  Worst case scenario, it smokes and I have to swap top ends when I get the other cylinders back from the shop, and I’m out the cost of the rings and gaskets.

 

Actually worst case would be to get it all back together and find the Hondamatic is shot lol. 
 

In playing around with it, it appears that the max reading rocking it back and forth is the measurable spot, and that was pretty consistent through the bore.  Down to .002ish anyhow. 

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1 hour ago, Misterclean said:

I've never used a bore gauge but from what i have seen,  it is subjective. Finding the perfect halfway point seems to be difficult at first until you get the feel for it. The top measurement is extremely important for me because that is the factory bore with no wear. I am like you......when in doubt just bore it.. Just a few more bucks and the waiting time....ugh

I agree , I would never re-ring an engine , not only is there  egg shaping of the hole to worry about , but then tempering of the steel from heat ,  second time around may be not too good , puts a glaze on the steel and new rings might not seat right , not worth the chance of all that work and it smokes or not be 100% , or not last as long as it could have --- G+H usually gets back to you in 7-10 days 

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7 minutes ago, Fishfiles said:

I agree , I would never re-ring an engine , not only is there  egg shaping of the hole to worry about , but then tempering of the steel from heat ,  second time around may be not too good , puts a glaze on the steel and new rings might not seat right , not worth the chance of all that work and it smokes or not be 100% , or not last as long as it could have --- G+H usually gets back to you in 7-10 days 

Yes, just because it doesn't smoke doesn't mean all is good because we all know there is quite a bit of wear and taper that drastically reduces the longevity of the build. 

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in my 30 yrs of doing this work, i've never used a bore tool. i take the rings, slide them one by one down into the cylinder, then hold it up to a light, if the cylinder or rings are bad ?, light will show through the rings. with the naked eye, you can tell if the rings are bad. most times i'll use my caliber's to measure the bore at the top of the cylinder, if its out there ?, then i have it bored.

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Penny wise and dollar foolish , well I guess if you have the time to go back into them and do it over again , then re-ringing a previous ran  bore is the way to go , LOL

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2 hours ago, shadetree said:

in my 30 yrs of doing this work, i've never used a bore tool. i take the rings, slide them one by one down into the cylinder, then hold it up to a light, if the cylinder or rings are bad ?, light will show through the rings. with the naked eye, you can tell if the rings are bad. most times i'll use my caliber's to measure the bore at the top of the cylinder, if its out there ?, then i have it bored.

You should measure in the middle of the stroke where it is worn the most. It can be 5 to 7 thousandths difference in ring gap measurements between the top and middle.....I've seen more but not usually. 

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You're good to go with that cylinder Jeep, just hone it. Then measure ring gaps with the new ring set in three places (top of bore 1/2" down, center of bore/halfway through the stroke, bottom of the stroke) to prove that you're within spec. Honda's are designed to have low piston speeds so taper or belling not a problem unless the cylinder was severely overheated several times.

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3 hours ago, Fishfiles said:

Penny wise and dollar foolish , well I guess if you have the time to go back into them and do it over again , then re-ringing a previous ran  bore is the way to go , LOL


Well I’ve had a 420 that had a bad crank, so the new top end started smoking after a few rides.  I honed that one with new rings and it’s still good to go now 5-6 years later.

 

If the measurements were close to service limit I’d probably err on the side of caution, but given I’m only .002-004 over stock and measurements are well within the service limits, I’m going to give it a try. 
 

This will be my personal bike so if it doesn’t hold up I’ll swap out a fresh bore/new piston when I get them back from my machinist guy. He does good work and is cheap, but I can’t rush him, so I’m going to experiment a bit here and see how it goes.

 

Bottom end has been gone through so I can swap top ends without pulling the motor again if it comes to that.

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8 hours ago, Misterclean said:

You should measure in the middle of the stroke where it is worn the most. It can be 5 to 7 thousandths difference in ring gap measurements between the top and middle.....I've seen more but not usually. 

i should have been alittle more clearer, i measure the top, middle, and bottom with rings. most times i end up boring the cylinder just to play if safe. once in a while, i can hone, new rings, run it, but not very much.

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5 hours ago, shadetree said:

i should have been alittle more clearer, i measure the top, middle, and bottom with rings. most times i end up boring the cylinder just to play if safe. once in a while, i can hone, new rings, run it, but not very much.

Ok. I get it now. I thought it was cylinder wear measurements. I feel better for you now. That's not bad if measuring ring gap. Ring gap is about a 3 or 4 multipler ratio to cylinder measurents.

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23 minutes ago, Misterclean said:

Ok. I get it now. I thought it was cylinder wear measurements. I feel better for you now. That's not bad if measuring ring gap. Ring gap is about a 3 or 4 multipler ratio to cylinder measurents.

on ring end gap, i like to see about 1/32 on the gap, anything larger than this, tells me it will smoke ?, or not enough compression ?.

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33 minutes ago, shadetree said:

on ring end gap, i like to see about 1/32 on the gap, anything larger than this, tells me it will smoke ?, or not enough compression ?.

The most important reason that a piston/ring to cylinder measurement is a small as possible is to eliminate piston slap. Cylinder, piston and ring wear wear at a exponential rate as slap increases. E = MC squared.

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1 hour ago, Misterclean said:

The most important reason that a piston/ring to cylinder measurement is a small as possible is to eliminate piston slap. Cylinder, piston and ring wear wear at a exponential rate as slap increases.

 

^^^^ THIS ^^^^

 

1 hour ago, Misterclean said:

E = MC squared.

 

^^^ Don't be fooled by that nonsense ^^^ Energy is not the same entity as mass. And energy and mass cannot be changed into one another. There is no physical relationship whatsoever between the properties of mass and properties of energy. The only relationship Albert understood was incest. The evil twisted idiot married his cousin, then married her daughter for cryin' out loud !!!!

 

EDIT: Sorry I didn't intend to come across as an attacker. I'm not.... I just can't stand lies of any sort. Incestuous evil brainwashers like Einstein in particular light me up!

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4 hours ago, retro said:

 

^^^^ THIS ^^^^

 

 

^^^ Don't be fooled by that nonsense ^^^ Energy is not the same entity as mass. And energy and mass cannot be changed into one another. There is no physical relationship whatsoever between the properties of mass and properties of energy. The only relationship Albert understood was incest. The evil twisted idiot married his cousin, then married her daughter for cryin' out loud !!!!

 

EDIT: Sorry I didn't intend to come across as an attacker. I'm not.... I just can't stand lies of any sort. Incestuous evil brainwashers like Einstein in particular light me up!

Ok. The theory of relativity is the most proven equation in the world. Every physicist relies on it being true.

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And because E-MC2 is completely false the idiots had to go on to make up more crap like black holes, dark matter and dark energy to prop up their idiotic imagination of the nature of reality. That's why they are known as quackademics.

 

Isaac Newton was another of their twisted disinfo puppets. There is no such thing as gravity, only density, buoyancy and magnetism, The apple that fell from a tree and hit poor Isaac on the head must have knocked him out. It's just a child's tale anyway, a liar telling a lie.

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1 minute ago, retro said:

And because E-MC2 is completely false the idiots had to go on to make up more crap like black holes, dark matter and dark energy to prop up their idiotic imagination of the nature of reality. That's why they are known as quackademics.

 

Isaac Newton was another of their twisted disinfo puppets. There is no such thing as gravity, only density, buoyancy and magnetism, The apple that fell from a tree and hit poor Isaac on the head must have knocked him out. It's just a child's tale anyway, a liar telling a lie.

So you believe in a flat earth?

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I don't believe in anything, mind is open. The earth appears to be perfectly stationary though, below the stationary Polaris and the oceans are certainly perfectly level. Earth is definitely not a spinning ball spinning around another ball and hurtling through any sort of imaginary "space". Everything NASA ever published is false and/or photoshopped. One day we will discover the truth whether our plane is flat, concave or whatever.....?

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My best guess is our realm is probably shaped and held by our magnetic field -- which is bowl shaped -- so our realm may be bowl shaped as well, confined within the flip-ring and confinement dome of the bowl shaped field resulting in a similar field-held shape?

 

The Holy Bible creation stories explain a motionless and stationary realm resting on pillars with the firmament separating the waters from the waters.... That indicates my best guess confinement dome and flip-ring thinking may be probable at least.... Ya don't have to be a bible believer to see that the sun and moon are very near (less than 100 ,miles away) and that the moon is a luminary like the sun, not a dusty rock that anyone could ever travel to or walk on. Ya don't have to be a bible believer to see that all of our surface waters are perfectly level either. Point a telescope across Lake Pontchartrain (25 miles) and you'll see the opposite shore, impossible on a globe. No where within the bible is there any reference to a globe or ball shape either, rather there is one brief mention of a circle. A circle is a 2D shape, not a 3D body.

 

I am not a believer as I said, but I have read the bible and have an open mind. Some of it is likely truth.... perhaps the creation story is correct? Observably, in reality, it is so far....

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Lake Ponchartrain is close to home for me. Just 3 miles to the shore from my door and two miles of the 3 is flat marshland. You can drive to the end of Bayou  Lacombe on Lake Road and park.   I would like to try looking thru a  telescope across the lake. I wonder how many miles you can see before it curves out of view or does it. ———-  I have been out on the open water on ships and I was convinced that I could see the curvature of the Earth. 
 

Back to the curvature of the bore.  If you put a fresh ring into the bore. Square the ring up and  hold the jug up to the light. If the bore is badly out of round / egg shaped you might see light between the ring and bore. 
 

I am sticking with my thoughts.  It is best to bore and renew a used hole. Unless you are working on a budget and have the time to do the job over when it doesn’t last as long.  
 

A set of rings cost $50.   A g+h bore job with piston and parts is $249 now days.  So for $200 you getting a new piston machined to specs of a fresh bore and peace of mind it is right. It is going to last longer.  

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Well after running my hone through this one a few times, it didn’t clean up as well as I’d hoped.   
 

So looks like off the G&H with it.

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1 hour ago, jeepwm69 said:

Well after running my hone through this one a few times, it didn’t clean up as well as I’d hoped.   
 

So looks like off the G&H with it.

haha...its only money.....right ?..lol.

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