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[ILENGINE]

Actually Bert I am going to add to the confusion. I went through my bone yard yesterday and actually pulled out a damaged FB25 with a type 5 engine, but I can only find diagrams for the type 1,2, and 4. It is using the same ring as the other types so no change there that I can report.

 

[tom3]

I think the arrow deal on the piston is to get the piston oriented right for the wrist pin offset. Pins are sometimes off center to compensate for the direction of the crankshaft rotation, reduce piston wear and slap. I'd guess many of these little two strokes just use a centered pin, no arrow. Those engines are pretty much junk when new. Some pistons also have a pin to locate the ring, those would need to be oriented correctly with the arrow indication to have the ring gap and ports setup right.

 

[PTmowerMech]

This blower was already in the junk pile. But Bert got my brain working on things I needed to know about 2 cycles. So I tore this one down and discovered the cylinder wasn't scored. For the price of the rings, (less than $5 each), I thought what the hell. Put $5 into it, sell it for $45. Make a little change and get some experience. Win win.

LOL. It was just my bad luck that the ring part number wasn't correct. But the rings I got were too big.

 

[bertsmobile1]

Forget the parts books, they are obviously wrong
measure your barrel & piston.
Bore , from the barrel
Ring width from the piston
Ring depth from the piston or old ring.

Also the piston diameter would be useful.

That is all that is important
1.39" on the closed ring will probably be 36mm bore
And 36mm rings usually come in 1mm 1.2mm & 1.5mm.
Some really cheap Chinese engine go down to 0.9mm rings
The download a catalogue from a ring maker that has a list of rings by bore

If you are going to be doing this you will need these skills to circumvent equipment makers catalogue & parts listing short comings.
Once yu know the ring size you are looking for ( rather than the application ) then you can search for a ring.
You will probably end up getting some from China or HK for under $ 1

 

[PTmowerMech]

Forget the parts books, they are obviously wrong
measure your barrel & piston.
Bore , from the barrel
Ring width from the piston
Ring depth from the piston or old ring.

Also the piston diameter would be useful.

That is all that is important
1.39" on the closed ring will probably be 36mm bore
And 36mm rings usually come in 1mm 1.2mm & 1.5mm.
Some really cheap Chinese engine go down to 0.9mm rings
The download a catalogue from a ring maker that has a list of rings by bore

If you are going to be doing this you will need these skills to circumvent equipment makers catalogue & parts listing short comings.
Once yu know the ring size you are looking for ( rather than the application ) then you can search for a ring.
You will probably end up getting some from China or HK for under $ 1

Thanks Bert. I just measured the bore. 1.34.
I take you've into this a few times. Makes good sense. Almost guaranteed to get what you need. Instead of what the books say you need.

 

[bertsmobile1]

So that would be a 34mm bore with a little wear.
Despite the plethora of makes & models out there the bores are very much standard
Here is 6 of 34 x 1.2 @ < $1 each delivered. 34mm rings from Alli Express
If they fit make a note of where you got them from and their part number then put the other 2 pair on evilpay / craigs stating that they fit the FB 25 Weedeater in place of the oversized 545154001 rings supplied by Husqvarna. Use your profits to buy A set of small ring compressors like these. Wally or HF chould have them for peanuts so the next time you won't break a ring.
The metal ones are better and priced accordingly.
I shift a lot of rings cause I buy them like this 100 ring pack
and this is the local price for rings down here.
Now the Ali Express price is US $ so that makes them just under $ 1 Aus and postage on a ring is $ 2 Aust and he is paying less than that because I know where they are coming from so $ 7 profit is a nice % mark up.
Never going to be rich doing this but it means that I can end up with the pair I sold to the customer @ $ 5 each plus 9 more pair to keep for stock effectively for free, plus I repaired a trimer for 1/3 what the dealer quoted him.
Being an independent workshop I can not get access to genuine parts if my after market wholesalers do not stock them and for things like rings, they really only stock Kawasaki ,Briggs , Victa, Kohler & Honda because the volume throughput of other brands is too small.
AliiExpress is a Chinese version of Ebay so most of the stuff is being sold at Chinese Retail prices
If you go to Alibaba, most of those will be direct from the factory so cheaper still but freight is always an add on and there are minimum lot sizes.
When I get something in that needs parts that are not readily available locally then these two sites are my first stop unless I know I can get them from some of the factories I already deal directly with.
Same story, buy an economically sized pack then flog off the excess.
Usually I am sort of up front & the usual tag line is "excess stock from repairing a ?????? no idea waht else it may fit"
First one was a clutch for a Briggs fun cart $ 120 locally for a clutch for a 30 year old toy go-cart.
Had to buy 20 clutches and sold the excess 19 @ $ 30 each in 2 days seems I was not alone.

 

[PTmowerMech]

Thanks Bert. I've got all those links bokmarked.

But a whole pack, sell one or the price of the whole pack.

BTW, I'm glad I tore this "junk" blower down. Knowing what's inside it, and how easy it was, to tear down and put back together, might keep me from junking them in the spring. I know enough to look at the cylinder before doing it. This one wasn't scored at all. That's why I picked it. A scored cylinder, IMO is junk.
For $4 I can put a new ring in this, sell it or $45 to $55. That's not bad for maybe an hour. (probably 30 minutes) after a little more experience.

 

[bertsmobile1]

Not bad for the NEXT one you do.
Unfortunately you rarely get exact repeat work so you have to factor in a whole lot more research hours.
Searching for stuff via Aliexpress or Allibaba con be a regular PIA as they are written in Chinese then translated back into English so you get some funny results.
I found a factory that cuts cube carb gaskets which was good but they eventually shoved me off to their main retailer.
In the USA you could probably move 100 repair kits a month but down here it would take 10 years.
I also found a battery supplier and a mod that will do wiring looms ( min 50 ) at an affordable price.
When you can get 2kg of heat shrink tube for $ 30 instead of $ 15 a length local price then you can afford to strengthen connectors & it does look a lot more professional.
When I kicked off , apart from watching every Donnyboy87 & Taryl Fixes All videos on You tube I was spending about 3 hours of research for every hour with a tool in my hand.
Now days it is about 15 min, excluding the time I spend here & the other 1/2 dozen forums, but they are mostly coffee breaks, diversions when writing a bill or zone out time.

 

[PTmowerMech]

AliExpress seems to take a long time getting parts here. (If I ordered today, it would be 1/19 before it gets here.)
I've found some one ebay, that are the same size, for about the same price. But they all list it for being rings to fit a Stihl. In other listings, for the same ring set, it shows the piston, with two slots in the piston, where as this Weed Eater brand only has on. Being the same size bore, is it possible I can only use one, and have an extra ring?
Note at the bottom, it's 1.5mm thickness. I think that's too thick. I'm getting 1.4 on my calipers.
4pcs Yard Piston Ring Set Parts For Stihl FS45 FS75 FS80 FS85 34mm Bore Trimmer
Brand New

 

[bertsmobile1]

You can't have everything.
When you don't pay separate freight then the vendor is going to send it the cheapest way.
With transport speed costs money.
My freight agent used to get motorcycles shipped from east coast to Longbeach in CA for around $ 300..
Down side is some times it took close to a year to get there .
He could also get it there in a week or less but that cost more than the sea freight USA to Aust.

1,4 mm sounds like a funny size
USA Rings generally go up in 64 ths then 16 ths to 3/16 th.

Metric rings generally go .8 , 1 , 1.2 , 1.5 then in .5 up to 4 mm

Did you measure it with a micrometer or a vernier ? and if so what was the accuracy of the measuring tool.

As for the ebay vendor, I would be weary of buying anything from them.
They are a disposal / surplus agent .
Click on "other items" and you will see they sell just about everything.
These vendors buy whatever is cheap in China then sell in it the USA ( & OZ ) .
They have no knowledge about what they are selling and no way of doing any checking.
Now they could be overproduction surplus from a ring factory and be quite good .
Or they could be defective rings bought from a scrap metal merchant .

Now for the rings themselves.
I try not to mix single ring & two ring rings.
Weather they have a different profile is way beyond my knowledge