Correct Cylinder Liner?

KentJ · Jul 11, 2015

Hi all,

I finally have all my new engine parts in front of me and as I was taking my new cylinder liner out of the packaging for the first time (I've had it for months now) I noticed that it is marked "3".

Does this refer to the sizing? I only see reference to size 1 and 2 in the manual.

My old liner got scored up when the piston ring broke but my piston is fine (see http://husaberg.org/mechanical/20178-worn-cam.html) so I'm reusing that. The piston is a Group 1 and the old liner is marked "2".

I measured the compression ring end gap in both old and new liners and the new liner seems slightly smaller (.3mm gap vs .37mm), so it would seem to me that "3" isn't a larger size. I don't have a bore gauge to actually verify the bore diameters.

Anyways, what does the marking refer to, and is this the correct liner for my group 1 piston?

Thanks,

bushmechanic · Jul 11, 2015

best way it to use a bore gauge and a micrometer to measure the piston to liner clearance

if that's not possible pop the piston you are going to use in the liner and measure the piston to liner clearance with a feeler gauge, its actually very accurate by comparison since there are less operations involved.

refer to the owners manual found in "service manuals" section for the clearance and where on the piston to measure it.

based on the difference in ring gaps you've measured id say you will be fine but it always pays to check everything twice and then check it again.

KentJ · Jul 11, 2015

Using the feelers it seems that both liners have the same (similar) clearances, but I'm not real confident with the precision of that method (at least not when done by me). I'm sure I know people with a bore gauge so I'll check it out that way to be sure.

Thanks!

bushmechanic · Jul 11, 2015

sounds good, maybe take the cases and the case bolts as well and check that the liner is still reasonably round when installed in the cases

Taffy · Jul 12, 2015

the ring size is the same regardless what they do to the pistons OK?

regards

Taffy

KentJ · Jul 13, 2015

So I mic'd the old liner, new liner and piston but I think I'm just as confused as I was before.

According to the specs in the manual the difference between the smallest size 1 liner (100.00mm) and the largest size 2 liner (100.025mm) is only .025mm. That's less than .001" difference between the smallest acceptable bore and the largest size 2. Really? Am I misreading or did they put the decimal in the wrong place? The wear limit on the piston is .12mm, so 10x what is acceptable in the cylinder liners...

Anyways, the new liner gives .0027" (.0686mm) clearance for the old piston, so I'm satisfied that the new liner is not over sized. It is slightly smaller than the old, worn liner. The clearance we measured is actually little less than the factory numbers (.072mm to .097mm) but if we rounded to the nearest .25 thou then that would account for that.

And yes Canada is part of the Commonwealth, but you don't see too many metric micrometer sets here...

-Kent

Taffy · Jul 14, 2015

remember the rules!

use 'thou's' up to a MM.

use MM up to an inch (well 25mm anyway...)
use inches from then on for a couple of feet
then you have a choice: yards or metres.
I use about three yards then I go to metres
then we always go to miles like 'quarter mile' and 'half mile'.

honestly you lot, you make it sound so difficult!!!!

the best one in our workshop is;
"there are 40 thou in a millimetre!"

with two apprentices here I'm making sure that my way of working will continue inpertuity!

Taffy

bushmechanic · Jul 14, 2015

it is only difficult if you get it wrong LOL

"40 thou per millimeter" is the most common mistake made by "mechanics"

its closer to 39

25.4mm = 1 inch

1 thou = 0.0254mm

1mm = 39.3700787 thou

Taffy · Jul 14, 2015

what the phuq are you on about? since when did I or any mechanic out there need 40 thou when measuring millimetres?

maybe if you worked as a mechanic you'd know that there is no relevance to your comment-again!

it is said as a source, there is no way I'm putting thou and mills together and getting any kind of mistake?

truly a load of tosh once again.

you don't half come out with some rubbish

Taffy

bushmechanic · Jul 14, 2015

Taffy you wrote there are 40 thou to the milimeter .. that is wrong

im a qualified diesel fitter, done plenty of work as a mechanic

Taffy said:
what the phuq are you on about? since when did I or any mechanic out there need 40 thou when measuring millimetres?

maybe if you worked as a mechanic you'd know that there is no relevance to your comment-again!

it is said as a source, there is no way I'm putting thou and mills together and getting any kind of mistake?

truly a load of tosh once again.

you don't half come out with some rubbish

Taffy

Taffy said:
the best one in our workshop is;

"there are 40 thou in a millimetre!"

Taffy · Jul 14, 2015

OK smart arse

give me an example of how I could make a catastrophic mistake of using 39 thou when instead of a millimetre?

you're the clever arse again?

bushmechanic · Jul 14, 2015

Taffy said:
OK smart arse

give me an example of how I could make a catastrophic mistake of using 39 thou when instead of a millimetre?

you're the clever arse again?

its not about making catastrophic mistakes with figures. its the members who read misinformation who may be mislead about units of measurement

you wrote "there are 40 thou to the millimeter"

not having a go at you for doing so as its an old phrase often used by "mechanics" and it is in fact wrong

that is all

Taffy · Jul 14, 2015

look here smart arse, I've asked you once and I'll ask you again: give me an example of where a mechanic would make a mistake using those figures!

and if he wouldn't then why be a petulant little s&^t and say anything?

I'll say to anyone here

40 thou to a millimetre is a perfectly good measurement for what you will want it for. I've never had cause to worry about half of one thou at 40 thou.

Keep It Simple Stupid. (KISS) something you should find easy to do bushie!

since when could you speak for Orange "off the cuff" bushie? got a camersa into his workshop have you?

Taffy

kenny87 · Jul 14, 2015

Seriously?

bushmechanic · Jul 14, 2015

LOL

the mistake occurs when someone thinks 40 thou = 1mm and uses it for conversion between metric and imperial

it doesn't matter what the error is relatively .. if its wrong its wrong

if 40 to 1 is good enough for a UK garden shed mechanic so be it , however people should know THIS CONVERSION IS WRONG

ol taffwad ya really don't like being found out do ya mate

bergbro · Jul 14, 2015

FFS. Not this **** again........

Can we keep this on HUSABERGS and not personalities please.

Yet another thread has turned from useful information into a **** slinging match.

I come here for information on HUSABERGS not personal fights...... plenty of that going on in the rest of the world.

Taffy · Jul 15, 2015

as I thought. just s^&t for the sake of s^&t. no useful information, just bollocks again.

as i thought, you can't even give an example of a mistake that would come from this simple piece of basic maths.

Taffy

bushmechanic · Jul 16, 2015

Look, this 1 mm= 40 thou crap is wrong OK lads ?

it has nothing to do with personalities or opinion its just fact.

I will always take the piss out of anyone who abuses me for sharing facts, those who want me to ignore this personal abuse for the sake of their poor little eyes could take their own benevolent advice and ignore site content they don't want to see

example ? a 40 thou pin does not fit in a 1mm hole, same problem with any interference fit.

in the context of this thread a group I piston is 0.01mm smaller than a Group II piston this is at 100mm bore diameter

40 thou is 1.016mm instead of 1mm

this is 60% more wrong than the absolute difference between 2 pistons

relatively though this error is 160 times more wrong ! than the difference between the 2 pistons becasue the pistons are 100 times bigger

the worst case machining accuracy required to manufacture these pistons is +/- 0.0025mm which is a relative error of 0.000025 (in practice they do better than that)

the relative error of 40 thou to the mm is 0.016/1 = 0.016

which is 640 times worse than the manufacturer needs to be capable of in order to produce pistons

so you see it is actually a big deal .. there are not 40 thou to the millimeter!!

1 thou = 0.0254mm

Smash101 · Jul 16, 2015

Go watch the Disney movie "ice" and just let it go, let it go!

I'm no mechanic so I have no input but I like to learn, so let's keep it clean.

Ok let's get back to the topic.

bushmechanic · Jul 16, 2015

you mean the movie "frozen" right smash, not "ice"

hows that for an interesting fact ?

i expect you will now fire off a volley of obscene abuse and personal attacks then tell me to phug off LOL

Correct Cylinder Liner?

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