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So I decided to take a piston out of a NEW Weed Eater brand weed eater, and put it in a Weed Eater brand blower. Checked all the part numbers to make sure they matched. Which they did.
The problem was, the ring on the blower was shot. BUT the cylinder was still good. The new engine I had, has a longer crank, that's not slotted. (Because it's for a weed eater)

Anyways, long story short, instead of compressing the ring so I could slide it into the cylinder, then installing the rod onto the crankshaft, I did it assbackwards. Installed the rod/piston onto the crank, then tried to compress the ring/piston into the cylinder. Making it tough to see all sides of the ring. None the less, i snapped the ring.

What I learned, Install the piston into the cylinder, then connect the rod onto the crankshaft. I should've taken an extra second to do this right.

Instead of listing this blower for sale now, I'm waiting on a couple of rings.

A set of hand held ring compressors is about $ 10
All of the aftermarket parts suppliers do one.
A simple loop with 2 tangs that you clamp together with a pair of lock jaw pliers.
Next best, but short by a long way is a hose clamp or a hose plamp wrapped around a length of pop can
You can even use a soda bottle.

bertsmobile1 said:

A set of hand held ring compressors is about $ 10
All of the aftermarket parts suppliers do one.
A simple loop with 2 tangs that you clamp together with a pair of lock jaw pliers.
Next best, but short by a long way is a hose clamp or a hose plamp wrapped around a length of pop can
You can even use a soda bottle.

Click to expand...

Soda can.... That's a good idea.


BTW, something you told me the other day, in a different thread about cleaning out where the piston ring fits, Nylon string (I just discovered) works very good.

a hose clamp and a paper towel work good too,
use the towel for padding.

Scrubcadet10 said:

a hose clamp and a paper towel work good too,
use the towel for padding.

Click to expand...

I was thinking about cutting out an aluminum can just big enough to fit around the piston. With about 1/8th inch inside the cylinder. A little 2 cycle oil and it should slide right on in. May take two wraps around the piston.

Question: I was just watching a video (Donnyboy) on which direction to install a piston in a 2 cycle. I get the idea that the ring gap should not be line up with the exhaust or intake ports, because it could catch. Good video, in fact. Except his piston had an arrow on top of it. This weed eater piston (neither of them) have an arrow.

Because I can see through both ports and see that the ring pin isn't coming up there. But what about the 4 cut outs on both sides of the cylinder. And how can I be sure the ring gap isn't going to hit either one of those? The 4 cut outs, I can see by knowing where the ring pin is, and sliding it into the cylinder, isn't going to actually be in line with either of them. But extremely close to one of the.

A little feedback would be awesome.

Piston will only fit one direction. the ring pins are normally on the intake/carb side of the cylinder.

Question: The two rings I ordered were apparently the wrong ones.
I have FB 25 Weed eater brand Blower. And W25CB Weed Eater brand weed eater.

I ordered part number 545154001. These are a little too big.

Does anyone have the right part number for these two? Both should be the same.

That is the number I came up with for both models on my distributor website parts lookup system, and the official dealer Husqvarna parts lookup system.

ILENGINE said:

That is the number I came up with for both models on my distributor website parts lookup system, and the official dealer Husqvarna parts lookup system.

Click to expand...

I double checked this number. Triple checked it, actually. Both of the rings I got were the wrong ones.

Being wrong, do they not fit inside the cylinder or don't fit the groove on the piston. I am wondering if there has been a change in production and the piston and ring have been changed but use the same part numbers.

ILENGINE said:

Being wrong, do they not fit inside the cylinder or don't fit the groove on the piston. I am wondering if there has been a change in production and the piston and ring have been changed but use the same part numbers.

Click to expand...

The ring slides over the piston without touching either side. (just barely).

slip them in the bore.
If they fit without overlapping then the rings are correct.
Now try the piston in the bore, upside down.
There should be .002' to ,oo5" clearance between the piston & the bore
Two stroke rings have to work in both directions and tend to be a lot springier than 4 stroke rings as they have to make a reasonable seal or the engine will not be able to be started in order to bed in the ring.
This is why a lot of manuals tell youto put fuel / oil down the plug hole before initial use.

Even when you close the ring gap, it still slides over the piston.
OD on new ring is 1.57. OD on the other ring, which is also new is 1.39.

OK I went and pulled apart a junk SST25C which shows 530055120 which supercedes to the new 545154001 ring. The same ring and cylinder as your two items you are working on and measured the ring. The ring in the one I disassembled measured 1.39 OD.

ILENGINE said:

OK I went and pulled apart a junk SST25C which shows 530055120 which supercedes to the new 545154001 ring. The same ring and cylinder as your two items you are working on and measured the ring. The ring in the one I disassembled measured 1.39 OD.

Click to expand...

Thank you. Thanks the one I think. I wonder how that original number got tagged to that engine. I guess where it says "supersedes" it doesn't mean replaces. Because the 4001 ring definitely doesn't replace the 5120 ring.

PTmowerMech said:

Thank you. Thanks the one I think. I wonder how that original number got tagged to that engine. I guess where it says "supersedes" it doesn't mean replaces. Because the 4001 ring definitely doesn't replace the 5120 ring.

Click to expand...

No it means replaces. From further research there appears to be other people that have had the same issue with the ring/piston being too big for the existing cylinder. the cylinder part number also supercedes which makes me wonder if the bore didn't change and both have to be replaced to make it work.

ILENGINE said:

No it means replaces. From further research there appears to be other people that have had the same issue with the ring/piston being too big for the existing cylinder. the cylinder part number also supercedes which makes me wonder if the bore didn't change and both have to be replaced to make it work.

Click to expand...

That's a very good point. I haven't seen anything about that. But then again, I haven't looked at the matching numbers for the cylinder heads yet. I did find a ring on EBAY that may match. The pic shows the ring next to a scale. And from what I can see, is smaller than the one I just recieved. I'm gonna email and ask if his has a set of calipers to measure it. His part number is the one you gave me.

Seems that if they'd increase the bore, piston and rings, the part numbers would be different.

PTmowerMech said:

Soda can.... That's a good idea.


BTW, something you told me the other day, in a different thread about cleaning out where the piston ring fits, Nylon string (I just discovered) works very good.

Click to expand...

while it s not part of your current dilema.
FWIW, unless the new rings bind in the piston, then cleaning the ring groove is usually a no no.
The side gaps are measured in 0.00001 " and damage to th grooves you need a microscope to see will render the piston useless.
I found that one out the hard way .
Even the pistons & rings made for machines that needed to be pulled down every year for decokes ( yes I am that old ) should not have their grooves mechanically cleaned.
As for your current problem.
Weed Eaters are a throw away brand & not meant to be repaired.
This is why the piston comes without the arrow stamped into the top as that adds to the cost of the piston,

Getting back to your problem.
Generally I get rings from Italy ( Grandinni ) and always order them by bore, width & depth , then coatings and not by equipment brand.
Amreicans have a problem doing this because the EU use mm and not inches.
They also sell through ebay Italy but you will find them listed by bore then in the details see most of the different brands & models that they fit.
Just about any brand ring will fit.
There is no profit in selling a single ring through the dealer network so just about zero care is taken or when it is ( like Stihl ) the prices are disproportianely high to the cost of the equipment .
Down here there are no Weedeater parts available at all as they have no network being a chain store brand.

OTOH, you usually have to buy a full sleeve from them and I have found that listing the remaining rings turns a nice profit.
I sell them through ebay, packed in a plastic coin container which costs very little to post.

I did look up your model and noted that they do not publish any of the important mechanical specifications in the owners manual so there is no way for the mug end user to know what the bore & stroke is .
According to Jacks, there are 2 different engines for a FB 25 but according to the part numbers all the parts are the same si it looks like the ARI database got udated with the new number and they applied it to both engines.

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.

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.

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.

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

bertsmobile1 said:

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

Click to expand...

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.

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.

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.

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.

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

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

On my phone so this will be short.

The calipersI'm using are plastic. So the fun part is trying to figure out which way they're off. LoL.

I'm very careful not to squeeze too hard. But the 1.2 is what I get on the ends. So that's what I'm going with, from the site you linked.

From what I get from my cousin down there, almost everything is imported. So you folks are used to shipping times and costs.

Around 10 prime ministers ago we had the Keating Government
Prime Minister Keating had a funny idea about economics and really believed that a modern sofisticated advanced economy is based on service industries so he did everything he could to ruin agriculture & manufacturing.
He brought in "world parity pricing" so mines for instance could charge the much higher world price to local industry thus rendering them uncompetative.
Thus we have no manufacturing of any substance in this country any more.
The following Howard Government signed the USA - Australia free trade agreement which was the death knell for the automotive industry and now that it has gone there will never ever be any mass manufacturing in Australia any more.

Now getting back to your vernier.
Was that
1.2
1.20
or
1.200
IT does make a difference.

Finally got the rings in yesterday and pUT everything back together. And the FB25 runs pretty good.
I had some problem getting the carb adjusted. Probably because it's been setting for a while since I cleaned it. Still couldn't get a decent response time from low RPM to high.
But regardless of that. It does run good now.
The rings were a teeny bit thinner then the OEM. .03 vs .04oem.
I'm afraid they're going to slide passedan the pin eventually and really screw something up.