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Lannis Offline OP
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So I got my A65 cylinders back from the rebuilder's.

.040" over. One side (apparently badly scored and running low on cylinder wall meat) was lined with an .040 liner. The piston and rings fit well and slide nicely up and down the bore on that side.

The other side, no liner. Nice thick cylinder walls, though. The piston and rings slide about 1-3/4" from the top down the bore, and then jams ... TIGHT. Can't even move it with a plastic mallet, although I didn't tap very hard. If you try to install that same piston, sans rings from the bottom of the bore, it's not even close to being able to go in.

The cylinder has obviously been honed, but I think someone forgot the do the final check for piston fit in that bore.

Is it kosher and cricket to install a liner on one side and not the other? If I can't find anyone local who will deal with this if I take them the pistons, rings, and cylinder block (there used to be a guy who owned a small-engine dealer who was a B50MX racer once and redid my head for me, but I think he's out of that business, I'll go see tomorrow morning), I will take it to them, but most guys locally with engine shops make the sign of the Cross and throw garlic at me if they see an old Brit engine part coming at them.

If that happens, I have a nice little wooden crate ready to go. Is there anyone here on the list, or do we know someone's shop who isn't backed up for 2 years with work, who can tackle completing the bore on this cylinder so that the piston has the right clearance and the rings the right gap? I know that rebuilders are busy, but this is a hour or two job for someone who knows what he's about ....

Hope springs eternal! Thanks for any help you can give me.

Lannis


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I'd ring them. I guess the ring end gap closes and jams the ring. It's like they haven't bored it. Usually people bore slightly small and hone to size with a ridged hone, but you have to be careful to hone it all the same all the way down. Using a bore mic to check as you go. If a hone spends more time at the top it will be bigger.

If the ring end gap is ok at the top but closes as you push it down it indicates taper. So check that and tell them what's happening. I expect they would want to fix it.


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Originally Posted by Mark Parker
I'd ring them. I guess the ring end gap closes and jams the ring. It's like they haven't bored it. Usually people bore slightly small and hone to size with a ridged hone, but you have to be careful to hone it all the same all the way down. Using a bore mic to check as you go. If a hone spends more time at the top it will be bigger.

If the ring end gap is ok at the top but closes as you push it down it indicates taper. So check that and tell them what's happening. I expect they would want to fix it.

Mark -

I have a bore gauge and I'll gauge it tomorrow and report back. But I think the ring check is superfluous because even a piston with no rings will go only about halfway down the bore from the top and then jams tight. I'll set up the gauge and do a profile of the bore, the bore guy will probably like to know about how much he has to cut before he gets out his own gauges.

How much can actually be "honed" off of a bore if you're trying to correct something like this?

Lannis


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Sounds like the firm that did the rebuild/bore etc made a right balls up.
Normally when the cylinder is a bit thin at the side the bloke boring it will move the
tool over and bore the thing back toward the centre. I have never had an a65 barrel
that will not bore to +40, some are a little thinner at the outside than others but
they are ok. To fit a liner he must have gone +100 anyway.
If it was me, he'd get the lot back and be told to sort it out. Seems like he can't use
a parallel hone either.
Hope you haven't paid him yet..........

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Lannis Offline OP
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Well, just trying to get it going for the spring.... no time for a lot of back and forth. Anyone can screw up....

Lannis


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You can hone a few thou out if you have the right type of hone. Probably not just a hand held one. It needs to be right. Both shops near here would be able to correct it but the hole needs to be square in the block when finished. Ask someone near you if they can do it. Mike gauge with a dial are the easiest and quickest, I had mike gauges that you need to tighten remove and read that are so hard the piston not going down is probably enough to convey what's needed.


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I don’t get why he didn’t advise sleeving being both sides back to standard.


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Maybe Lannis had the pistons already.


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If the barrel casting is getting a bit thin, boring it even bigger and sleeving will make it even weaker


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Trouble with using honing to cure a tapered bore is you are likely to end up with a bigger tapered bore, honing follows the current hole and will not normally selectively widen just a section. I have seen people use hone's to rebore lawn mower barrels, they start off with all the wear at the top and when resized to next oversize you get the wear pattern of a worn bore replicated 10 thou bigger.

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If it was thin to begin with now it will be wafer thin. That's the weak spot for these things. Get a different barrel and start fresh.
PS I have had them break at the base. Not pretty!

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Lannis,
A couple of observations: Nothing wrong with sleeving one side, if only one side needs it. I assume the machinist sleeved to .040" over because the other side, in the machinist's view, was going to clean up at .o40 over, and therefore you wouldn't incur the cost of installing a second sleeve. The downside is that you are now on the final overbore recommended by BSA. If I was putting in a sleeve, I would do both sides and put them back to the stock bore. Putting aside the failure to finish the other side of the cylinder, the most disturbing thing to me, is that apparently the machinist didn't call you after examining the cylinder and tell you what he was going to do. Did you give the machinist the pistons when you gave him the cylinders? I assume you have already paid him. As I see it, you have 3 choices:
1) Go back to your machinist, cylinder and piston in hand and tell him to fix the tight piston; or
2) Go back to your machinist, and tell him that you never agreed to installation of a sleeve at 2/3 of service life, and that you want him to remove the sleeve and install 2 new ones at the stock bore (you would expect to pay for one and you will probably have to pay for new pistons); or
3) If you no longer trust your machinist, send your cylinder and pistons to a well respected specialist and ask their advice. Ed V for instance. Ed often has pretty lengthy wait times. Someone I have used quite a bit, whose whose wait time is less is Randy Long, 610-286-5870. Randy is out side of Philadelphia. He is old school, and quite talented. He did my Velocette head and cylinder this past summer. I also used him for my Parillas and my Gilera. A lot of the high end BMW and Harley shops subcontract to him. His prices are reasonable.

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Originally Posted by pushrod tom
If it was thin to begin with now it will be wafer thin. That's the weak spot for these things. Get a different barrel and start fresh.
PS I have had them break at the base. Not pretty!

With all the comments to date, and with me having a close look at the cylinder bores, I've decided that I don't like these cylinders. I've included a couple of pictures that may or may not be helpful ... they are looking at the cylinders from the bottom, with the pistons in the bores.

Here's the lined one ...

[Linked Image]

If you look close you can see that the cylinder bore is razor thin on one side, and .15" thick on the other. This makes me question (A) Whether the bore still has enough meat on it to be safe and (B) Is it bored axially aligned? The liner is way over on one side of the cylinder bore.

The unlined one ...

[Linked Image]

It looks fine, not too thin anywhere, but still possibly not bored straight, since the wall at the base is .110" on one side and .190" on the other. I don't know whether that indicates a problem or not; it may have been a machinist correcting for improperly cast bores from the factory.

So I think the "Start Over" advice is what I'm going to do, and either bin this cylinder or give it to someone who can use it for something.

I have a spare cylinder, I think I picked it up at OVBSAOC swap meet one year. The bores mike to 2.968", which is real close to a .020" overbore for an A65. They're nice and smooth, not tapered or oval, although they don't look freshly honed.

[Linked Image]
[Linked Image]

I'll check the tappet bores in the morning, and check the cylinder base holes to make sure they match my '69 cases; I don't know what year this cylinder is.

I have 4 .020"-over pistons, but they're all in rougher shape than I want to use. One pair has some light scoring, and one of the other pair looks like a gudgeon pin clip came loose once upon a time, so it looks like I'll have to spring for new pistons. AND find a guy who can match them to rings and the bore. I'll try Edunham's guy, see how long it would take to do.

Thanks for the help so far, all, I'm sure I'll be back soon!

Lannis


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They are rarely cast even or bored even. There is not much side load anyway. But the second set look really nice.


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Lannis,
If you haven't called Randy all ready, give me a call. I will give you my cell on a PM.

Ed from NJ

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Originally Posted by edunham
Lannis,
If you haven't called Randy all ready, give me a call. I will give you my cell on a PM.

Ed from NJ

Ed - My mailbox was full, but I've cleaned it up now, if you want to send your cell again, I'm ready this time .... !

Lannis


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Originally Posted by edunham
Lannis,
If you haven't called Randy all ready, give me a call. I will give you my cell on a PM.

Ed from NJ

Ed -

Dude!

Lannis


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Originally Posted by Allan G
I don’t get why he didn’t advise sleeving being both sides back to standard.
Originally Posted by Mark Parker
Maybe Lannis had the pistons already.
I'll go with that. I once had a Trident barrel resleeved at +20 because those were the pistons I had.


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Originally Posted by DavidP
Originally Posted by Allan G
I don’t get why he didn’t advise sleeving being both sides back to standard.
Originally Posted by Mark Parker
Maybe Lannis had the pistons already.
I'll go with that. I once had a Trident barrel resleeved at +20 because those were the pistons I had.

arent trident barrels sleeved anyway? A65 iron ones are not, I wouldn't think it was a wise move to just sleeve one side and the cost of a set of pistons from MAP is so cheap for a set of JCC pistons that it isnt worth considering using an old set.

I did have a set of barrels bored to +60 to suit the pistons I had, but these were very low milage Ed V JE pistons and I already had new rings.


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I resent the PM with my number yesterday. Didn't you get it?

Ed from NJ

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Lannis:

I sure wouldn't use the one in your first pic!
with ought going into the engineering behind it EFFECTIVELY all the strength of the bore is only just the thickness of the sleeve . The original parent metal is strained (cast iron doesn't like tension) specially if the part of it is busted off as it appears to be in your pic

the only way to successfully rebore one with a busted out bit that goes into the case is by making a set of lines of sufficient thickness toTOTALY REMOVE the original ...obviously you need to take care not to machine out so much you bust through on the od of the liner and into the fins

Engine reco guys ( in my experience ) are a bunch of prima donnas and sure resist having to make up a set of custom liners

I rebored my A10 and removed ALL the original (broken) parent metal and ended up with liners with a 4mm wall thickness ...

there is NO structural strength between 2 cast iron cylinders .

Now the experts can howl me down but thats what i did and it worked really well !


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Unfortunately, the head bolts on to the barrel, not the liner so the tension strength is needed in
the barrel casting, likewise the case end. You are reliant on the fit of the liner to prevent it moving
and/or provide the strength to prevent the barrel cracking. This may be ok for someone plodding
one around but give it some stick and the barrel will crack if it's wall is very thin. In order to retain
some strength you can through bolt them but it's a fiddly job.
The replacement one you have there looks like a good one, they varied quite a lot from the factory.
If you have a later engine you will need to drill for 3/8 barrel studs and file the 2 front holes to slots.
I'm not a prima donna but have built quite a few a65's over the years and have seen a few cracked
barrels after blokes have had car liners with thick walls fitted. Removing the least amount of barrel
material is the desired way, thus retaining as much strength as possible. The spigots that protrude
below the actual bores are really a guide for the pistons and have little stress requirement, when
using long rods and short skirt pistons they can be cut back quite a bit and areas at the front and rear
cut away for rod clearance if needed without affecting strength.
BTW i'm not an expert but i do like to look at things logically.

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Nick L ...
the tension i am referring to in the original parent metal is the tension created when the liner is pressed into it. it cant be otherwise!

you said (partially correctly) :

"but give it some stick and the barrel will crack if it's wall is very thin. In order to retain
some strength you can through bolt them but it's a fiddly job."

through bolting will do NOTHING to relive the stress that the parent metal is under due to having a sleeve pressed in ....in Lannis's case particularly because the outer wall ( parent metal ) is broken

but you are spot on about "the barrel will crack if it's wall is very thin"

it was the amount of lined smashed up sleeved barrels i looked a while looking for a pair for the A10 that lead me to this conclusion

I am taking about horizontal stress not vertical


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Ahhhhh..........yes, norton barrels are renowned for cracking in that way when sleeved.
It's a fine line between getting the fit good and over doing it. The a10 used to have a
habit of cracking around the base until the later 'thick flange' type although i've known
blokes bore them to +80 and get away with it. Variations in manufacture i suppose.
I suppose most of my experience with these things is on racing bikes so may not be
so relevant for normal use. I did run an a65 barrel with +60 T140 pistons in for a while
that's +100 in a65 terms, i had to through bolt that one as it was right on the edge.........

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Lannis,
Sorry for all your trouble. I have used Ed V to resleeve, bore and fit pistons. He has all the parts on the shelf. Might give him a call on turn around. While you are waiting do the OPRV change I recommend at the top of this forum. These motors need better lubrication. I can send you the little valve,but you'll have to make the adaptor bushing

Mr Mike

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