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

[Landmark]

I knew that husqvarna had A cylinders B cylinders, A, B, and AB pistons for the 262 but i didnt know my 385 has A cylinder until i ordered a new meteor piston and it came as a B. What is the deal with all this A B AB stuff husky has done and how many saws are this way. I feel like i am discussing blood types and AB negitive is going to 'popup'. I assume it was this manufactured this way per years for some reason but do they still do this on the 5xx series? Sure makes you pay more attention when you're rebuilding a saw.

 

[Magic_Man]

Somebody correct me if I am wrong but I believe it has to do with the piston and bore size. Not all cylinders come out exactly the same, there is a few thousands variance. So they label them as A, B, AB, C etc.

 

[fearofpavement]

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

 

[Magic_Man]

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

I wonder if it's because of variance in the plating thickness after the machine process ?

 

[trooney]

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??

 

[Landmark]

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??

Or the Mayans

 

[Simondo]

My understanding is much the same as the posts so far . Machine Tolerance between the piston and cylinder , example i have is on a 242 meteor piston on B rating = 42mm bore 41.96 piston.

 

[Simondo]

Here is a B for the 262...you can see there is a different tolerance for the expansion characteristics of bore size compared to the figure i gave for the 242.
Mostly I put a B piston into cylinders that are original ones ...most i have come across are B or A/B so it should be safe. B seems to be the most common Meteor spec anyhow...OEM...cant comment as iv not bought one.

 

[Tor R]

It was an old system oem makers did, there was A B C D where A was smallest and so on. There is also different tolerance with some + marking.
Mahle and KS have mostly used A or B tolerance for Husky the last 20-30 years.
This A B piston system is some nonsens Meteor is still doing, it's a decade since Husky just went for AB piston.
Funny with Meteor, I bought one 262 A piston, 48mm, while the bigger piston B has dimension 47.95mm.

Dave, what dimension do Meteor 385 A and B piston have?

 

[Simondo]

It was an old system oem makers did, there was A B C D where A was smallest and so on. There is also different tolerance with some + marking.
Mahle and KS have mostly used A or B tolerance for Husky the last 20-30 years.
This A B piston system is some nonsens Meteor is still doing, it's a decade since Husky just went for AB piston.
Funny with Meteor, I bought one 262 A piston, 48mm, while the bigger piston B has dimension 47.95mm.

Dave, what dimension do Meteor 385 A and B piston have?

At least you can easily tell what the machine tolerance is with Meteor pistons looking on Ebay and seeing a box picture is helpful Iv found .

 

[Tor R]

At least you can easily tell what the machine tolerance is with Meteor pistons looking on Ebay and seeing a box picture is helpful Iv found .

I read someplaces that Magnus said A piston is kinda egg shape, it expand different compared to an B piston.
If you take 262 pistons as example, the tolerance between them are so little that it's nuts that Meteor doesnt just make AB piston as they do with 254 and Mahle do on both 254 and 262.
This A and B things just make it more difficult for customers.
Thats my two cent about A B AB system.

 

[MustangMike]

The A cylinder is supposed to be a bit tighter than the B cylinder. My 044#1 came from the factory with a B cylinder and an A/B piston. I think all the OEM Stihl pistons are A/B. The difference is not much, and it is rare you will have problems with it.

 

[Woodpecker]

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??

 

[jmssaws]

Mix them. Loose is fast

 

[Tor R]

The A cylinder is supposed to be a bit tighter than the B cylinder. My 044#1 came from the factory with a B cylinder and an A/B piston. I think all the OEM Stihl pistons are A/B. The difference is not much, and it is rare you will have problems with it.

I got a new 262 p&c it also has AB piston.
I am glad both Stihl and Husky quit this nonsens with A and B piston and made a piston in the middle way with AB.
Wish Meteor would do the same so people doesnt get nerveous about those things
A used A jug, many times it's sanded or honed, I would be surprise if it isnt already on B tolerance or close to it.
The only thing I wouldnt do is to trow an A piston in a B jug.
Someplaces I read a bit about combination A AB B C D piston in different type jugs, think it was from Stihl actually

 

[jmssaws]

I have measured a mountain of 66 cylinders and was very surprised at how little one wears,they almost dont.

 

[Tor R]

On As there was a discussion about those A B things.
http://www.arboristsite.com/community/threads/kolbenschmidt-husqvarna-254.266304/#post-5039394

 

[drf256]

Mix them. Loose is fast

That depends.

 

[cus_deluxe]

great thread dave, and keep the good info coming dudes. i had only heard of this stuff in passing before so im happy to learn something useful today!

 

[Landmark]

great thread dave, and keep the good info coming dudes. i had only heard of this stuff in passing before so im happy to learn something useful today!

I found out a while back when building some 262's. I assumed that husky stopped this when the 3xx series was introduced. Thats why i am so surprised my 385 is A type.........like me