What's with all this A and B stuff??

[Jon1212]

You're probably right Magic man. But I don't understand the plating process so I can't comment on why that is. Maybe the "Ancient Aliens " know??

@stihl sawing the man asked you a question.

 

[stihl sawing]

@stihl sawing the man asked you a question.

 

[Tor R]

That depends.

Agree, if we take 026 as example I wouldnt put an Meteor B piston in A jug.
A=43.95
AB=43.96
B=43.97

If we take 385 as example
A=53.94
B=53.95
C=53.96

I dont think I would sleep lousy using an B piston in an A jug as long the difference is just 0.01mm, but of course, A piston in A jug is ideal.

 

[drf256]

http://opeforum.com/threads/a-b-and-ab-cylinders.2054/

 

[Simondo]

Agree, if we take 026 as example I wouldnt put an Meteor B piston in A jug.
A=43.95
AB=43.96
B=43.97

If we take 385 as example
A=53.94
B=53.95
C=53.96

I dont think I would sleep lousy using an B piston in an A jug as long the difference is just 0.01mm, but of course, A piston in A jug is ideal.

That is why most "easy to get"..common size... Meteor pistons seem to be size...B.. right in the mid range A/B size.

 

[Tor R]

I know we had a discussion in another thread as Al pointed out.
I do have an 262 Meteor A piston, B piston, and a new Mahle AB piston. I dont have an micrometer big enough to check what the precise size they have, but I will get it done on tuesday and post up those dimensions.
I want to figure out this lol

 

[drf256]

Not sure why people would not want to do their best to match the piston and cylinder.

There's pretty much no way that the OEM went through the trouble on this system for no reason.

I'll be sticking to the correct lettered piston for the cylinder, thank you very much.

 

[Tor R]

I am with you Al.
I follow the letter also, last time I bought Meteor from the greek I put a note with my order so I got the A piston I needed and the B pistons.
Most of those 254/262 I've seen since 94 have had AB piston, doesnt mather if it's an A or B jug.
What I am most currious about is how do the oem AB piston fit into the Meteor A and B piston system, I'm probleby not the only one....

 

[Simondo]

Ok then Folks...take a close look at what "Meteor UK" has on the A B C spec...It looks awfully like the A B C is talking about piston only ??!! so one would think the end gap would be different if ..1 ring fits all.
This is a screen shot from the site.

 

[Landmark]

Ok then Folks...take a close look at what "Meteor UK" has on the A B C spec...It looks awfully like the A B C is talking about piston only ??!! so one would think the end gap would be different if ..1 ring fits all.
This is a screen shot from the site. View attachment 23950

Good info and i believe you are right. The ring gap would have to be effected by whichever piston used.

 

[Simondo]

Good info and i believe you are right. The ring gap would have to be effected by whichever piston used.

The piston rock ( at the skirt bottom ) would be affected by the one you put in if it was the smaller size in the larger size cylinder ...ring gap is a different matter by the look of it.

 

[MustangMike]

The ring gap will be determined by the cylinder, not the piston. Matching the piston should aid in long term durability, and the skirt properly sealing the port.

 

[Brewz]

I know we had a discussion in another thread as Al pointed out.
I do have an 262 Meteor A piston, B piston, and a new Mahle AB piston. I dont have an micrometer big enough to check what the precise size they have, but I will get it done on tuesday and post up those dimensions.
I want to figure out this lol

Every Stihl saw I have seen with original P&C had matching A or B Pistons to cylinders.

I have raised this as an issue with @Gentleman in the past.

If I order a piston from the HLSupply website, which i have done often, there is no way of knowing what I will get.

I will say here that it is a point of contention that will change my piston orders going forward.

 

[MustangMike]

As I previously stated, my 044 #1 came from the factory with a B cylinder and A/B piston. Also, all OEM Stihl pistons I have ordered have been A/B (no choice).

 

[Simondo]

For me this all comes down to the "Running tolerance".
There will be a amount factored into the final clearance of the piston in the cylinder when the engine is hot . This would need to remain as a constant over all the cylinder sizes ...A B C D ..... The corresponding A B C D...piston will have the tolerance in it, so matching up is giving you the "Known "tolerance.
The same size ring being issued suggests that from cylinder to cylinder it will give a end gap measurement within the required working tolerance.

 

[Tor R]

How many of your guys check the dimension of your jug before you order a piston?

 

[Simondo]

How many of your guys check the dimension of your jug before you order a piston?

I pop a new ring in to look at end gap and also look at the old ring end gap if i can....I don't measure a cylinder every time unless im not happy with it. I will measure the old and new piston to see what the difference is but I base ordering the new piston and ring on the letters on cylinder and piston mostly.

 

[WOODS]

Not sure why they all can't be the same size with today's advanced manufacturing capabilities... Maybe they need to try harder.

I'm not a machinist but all cutting tools wear, in addition to other mechanical variances, so I would assume that though tight tolerances are easier to maintain today than before there is still a range - driven mostly by economics. Though accuracy is generally more consistant than years ago, I believe rifles are still handpicked for certain customers due to variances inherant to tool wear.

Ron

 

[mdavlee]

I've never paid it any attention. .01mm is a 40% of a thousandth of an inch.

 

[Tor R]

View attachment 23950

i am glad you posted up this Simon, using your image to discuss.

Compared to many others I dont have much experience, nor have I seen so many 262 jugs that it mather, maybe 15.
I've never seen a 262 C jug or D jug.
Husky never had the options of ordering A B C D piston to 262, they only had one type piston, thats it, AB piston.
So why do Meteor offer 4 different options?
A jug, after worn out the first piston or second piston that A jug doesnt have A tolerance anymore, thats where all those 4 letters comes into play. If we take B cylinder we go one step up.
Hone an A cylinder, anyone think A piston is best match?
Those who follow the letter no mather what can do it for me, when my A piston is worn out it get an B piston.

Just my 2 cent about Meteor A B C D pistons