# Poulan ... what size is my engine?



## Gary1234 (Jan 27, 2006)

I purchased a Poulan 2250 (36cc) and decided to get a second Poulan for backup (they cost less than $50 on ebay). I decided to go with a 2375 (Wildthing ... 42cc) so I downloaded the parts list .... surprise ... the jug, crank and piston are the same part numbers as my 2250. In fact the part numbers for the jug, crank and piston are the same for Type 7 models 2050, 2150, 2175, 2250, 2450, 2550 and 2375. These model numbers cover chainsaws rated from 33cc to 42cc.

Is this a ploy to sell the same saw to a wider consumer target market or am I missing something.


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## bugfart (Jan 27, 2006)

Sounds like they are varying the stroke with pushrods.


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## SawTroll (Jan 27, 2006)

My brother has informed me of about the same observations, and he has been inside some of the saws in question (mostly Poulan buildt Partners). The ones he has been into _are_ the same, regardless of stated cc's.
He also informed me that they are so badly ported that it is real easy to get more power out of them.
Otherwise I know nothing about this issue....:bang:


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## shadetree (Jan 27, 2006)

*poulan*

Hi Gary
For the most part, what you say about the different model sizes, being for a wider market share, is right on the money.
Of course, there is a difference in the bore and or stroke size, from the 33cc engine to the 42cc though.
These saws, in my opinion are stricty for ocasional use, homeowner saws, and no more, as the price reflects. They get a bad rap on here from some, but all in all, they do a pretty good job, considering what you pay for them.
EHP owns Husqvarna, and Poulan, and a few others as well, and the model name and number switch, is not strickly , limited to Poulan. Seems like most brands does that some.
Shaedtree


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## Butch(OH) (Jan 27, 2006)

Gary1234 said:


> I purchased a Poulan 2250 (36cc) and decided to get a second Poulan for backup (they cost less than $50 on ebay). I decided to go with a 2375 (Wildthing ... 42cc) so I downloaded the parts list .... surprise ... the jug, crank and piston are the same part numbers as my 2250. In fact the part numbers for the jug, crank and piston are the same for Type 7 models 2050, 2150, 2175, 2250, 2450, 2550 and 2375. These model numbers cover chainsaws rated from 33cc to 42cc.
> 
> Is this a ploy to sell the same saw to a wider consumer target market or am I missing something.



No wonder our 2050 runs like a striped arsed ape, it's got a wild thing motor in it, LOL


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## retoocs555 (Jan 27, 2006)

Gary1234 said:


> I purchased a Poulan 2250 (36cc) and decided to get a second Poulan for backup (they cost less than $50 on ebay). I decided to go with a 2375 (Wildthing ... 42cc) so I downloaded the parts list .... surprise ... the jug, crank and piston are the same part numbers as my 2250. In fact the part numbers for the jug, crank and piston are the same for Type 7 models 2050, 2150, 2175, 2250, 2450, 2550 and 2375. These model numbers cover chainsaws rated from 33cc to 42cc.
> 
> Is this a ploy to sell the same saw to a wider consumer target market or am I missing something.



Yes. 

I think bugfart is right that they vary the stroke so they can interchange the same piston and cylinder. 

I don't believe they are lying about the displacement but the power increase as the displacement increases isn't as much as they would like for you to think.

I've been inside a lot of these and can confirm that the cylinders are identical and interchangeable between many of those models.


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## whatsnext (Jan 27, 2006)

retoocs555 said:


> Yes.
> 
> I think bugfart is right that they vary the stroke so they can interchange the same piston and cylinder.
> 
> ...



How is this possible? If the crank, piston and jug are the same no amount of con rod massaging is going to change anything. Even if he's mistaken about them all using the same crank you couldn't use the same cylinder and piston without having the port timing completely messed up. If Poulan uses the same replacement crank, piston, and jug they are either lying about the displacement or telling you to change to some standardized displacement if and when you waste your time rebuilding one of them.
John..


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## retoocs555 (Jan 27, 2006)

whatsnext said:


> How is this possible? If the crank, piston and jug are the same no amount of con rod massaging is going to change anything. Even if he's mistaken about them all using the same crank you couldn't use the same cylinder and piston without having the port timing completely messed up. If Poulan uses the same replacement crank, piston, and jug they are either lying about the displacement or telling you to change to some standardized displacement if and when you waste your time rebuilding one of them.
> John..



Well all I know is I have lots of different model poulans around here, 2050, 2150, 2250, wild things and so on and for the most part the cylinder is the same. I don't know about interchange of cranks and rods. Maybe you're right poulan is outright lying about the displacement on they're saws but I doubt it. I was just trying to logic out how it might be possible. 

Somebody has to save the poulans! No matter how much time I have to waste to do it


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## whatsnext (Jan 27, 2006)

Another thought would be that Poulan's web site Admin is a dope and he has all the breakdowns linked to the same .pdf . It would be kind of funny though if all the engines are the same, just mounted in a different chassis and with different stickers.
John...


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## Gary1234 (Jan 27, 2006)

*Here's a little more info ...*

I've got a Craftsman 36cc manual here and part #'s are ...
Cylinder #530012550 (sounds like it's designed for Poulan 2550)
Piston assembly #530071408
Crank assembly #530047062 (includes rod)

I also have the parts lists for Poulan models 2050, 2150, 2175, 2250, 2450, 2550 and 2375 ... all these have parts identical to those listed for the Craftsman. I havn't downloaded lists for all the Poulan saws ... there may be other saws that use these parts.

I appreciate comments so far, but for those who think the engine size can be altered when using the above listed parts ... please explain how??? Note that the crank/rod comes as an assembly. The Poulan saws come in different "types" as well as "models", I'm assuming that the early "types" are previous models. My Craftsman manual is for a Type 7 (and thus has the 2550 cylinder) .... the saw is a "re-badge" Poulan 2250.


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## timberwolf (Jan 27, 2006)

As posted above changing rod length makes 0 change to the CCs.

The answer is very simple, creative marketing to sell the same motor on different saws.

Wildthing has a stroke of close to 30.5mm and a bore of 42mm giving a 42.2 CC motor. (Swept volume) Marketed as a wildthing!

Exhaust port is about 7 mm High so 23.5mm of compressed height and 42 mm bore gives a 32.6 CC motor. (compressed volume) Marketed as whatever else!

And to account for the 36CC they are likely using the mean exhaust opening or something like that to come up with 36 CC.

3 or more production saws for the same cost of manufacturing 1.

Myth confirmed!


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## tony marks (Jan 27, 2006)

not advocating poulan as my little experience with them,taught me that they are not a saw i want to try an get any work out of. but the 46 cc saw is stronger than the 36cc saw.so its hard to understand the piston being the same size.
by the way i know an old climber who is till trying to work. he uses the little green 36cc version. says its the best saw he has owned. i once bought an 028 stihl from him,so i cant agree ,but thats his thinking on the matter.


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## rjh245 (Jan 27, 2006)

I was looking on the web site also...From the part numbers it looks as if the saw from 33 to 42cc's are the same thing with different lables on them. I guess it is a marketing trick.
Rob


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## shadetree (Jan 27, 2006)

*Poulan*

On my microfich, the Poulan 2050, 2150 2175, uses cyl pt# 530069606
The 2375 uses, pt# 530069607
The 2250 uses cyl pt# 530071252, and the 2450 and the 2550 uses cyl pt# 530069608
The pistons, for these different groups,also uses different part #s, but I didnt write them down.
Shadetree


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## Gary1234 (Jan 27, 2006)

*Shadetree ... is your info current?*

Shadetree ... your part #'s are correct for Poulans part list for saw Types 1-5 (parts list 530083628) except for the last part (530069608) which is a muffler gasket. I am assuming that these are older models of Poultan saws (but I could be wrong). The types of saws are listed on 3 pages ... Type 1-5, Type 6 and Type 7 ... it's Type 7 that seems to lump all the saws as using the same parts (My (new) 2250 manual's parts list is identical to Type 7). 

My assumption seems to be enforced by my Craftsman owners manual. You can find the parts lists at www.poulan.com ... go to search and type in the saw model. Each part list download contains all 3 Types of saw.

I'd email Poulan but they only supply a snail mail address.


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## shadetree (Jan 27, 2006)

Gary you are right, I mixed that last part# up, it should have been,530069932. I went to the empart site where I order parts, and as you said, all type 6 and 7s use the same part # on the cyl 530012550, but after you go back to type 5 and below, the cyl part# change.
So I dont have any Idea whats going on with that.


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## Gary1234 (Jan 27, 2006)

*saving $$$*

So from all this gibberish ... if you are purchasing a Poulan or a Craftsman, look at the parts list in the owners manual. If the cylinder is listed as part #530012550 you are purchasing a 42cc chainsaw (even if the chainsaw stickers say 33cc or 36cc) ... it'll pay to buy the least expensive chainsaw that uses the 2550 cylinder.


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## shadetree (Jan 28, 2006)

Gary I went out to my shop, last night, and counted, 5 poulan saws, in for warrenty repair, and only one, was a type 6 it was a wildthing, the rest was type 5 or less. Most of the saws and stuff being sold on ebay, is factory reconditioned (I have seen them in stores too, being sold as new) , I wonder if that has anything to do with this?
Shadetree


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## bugfart (Jan 28, 2006)

Holy crap.
Just when we come up with a perfectly good conspiracy theory, some-one trumps it.

But a new player has raised it's head. type 7 ?
What is the type hype all about? I use the type that cut wood. What ever type 7 is needs to be stopped.

Type 7 is "number 4". (Korean slang for "sucks".)


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## shadetree (Jan 28, 2006)

bugfart, Iam not sure but I believe you might need type 2 to cut wood with. Type 7 is the type you bake cakes with, ahhhh Iam pretty sure!!!!!
But dont worry I wont turn you in to the Poulan Police This Time!!!!
Sure shows ya how f:censored: bored we are, dont it!!!! 
shadetree


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## Gary1234 (Jan 28, 2006)

*Shadetree ... repair costs??*

Shadetree .... with the cost of a Poulan running less than $100 (including shipping costs), does it make sense to get one repaired? I would think the average repair costs would be greater than the cost of a new or reconditioned saw.


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## shadetree (Jan 29, 2006)

Hi Gary
You are right, but most of the repairs I do on Poulans, is under warrenty, I mean Poulan pays me to repair them.
Poulan, and Poulan pro has a really good warrenty. The green ones has a one year, and the yellow has a two year. And unlike alot of companys I do business with, they back their stuff up really well.
But you would be surprised, how many people dont even no that thay have a warrenty.
But still I have alot of people that will bring a saw, or something to me, to be repaired, that maybe cost $100.00 new, and is going to cost $50.00 to repair, and they still want it fixed, even though I tell them its not worth it.
I dont know why!!! The older I get the more I relize, how little I understand lol
Shadetree


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## Brian B. (Feb 23, 2013)

Gary1234 said:


> So from all this gibberish ... if you are purchasing a Poulan or a Craftsman, look at the parts list in the owners manual. If the cylinder is listed as part #530012550 you are purchasing a 42cc chainsaw (even if the chainsaw stickers say 33cc or 36cc) ... it'll pay to buy the least expensive chainsaw that uses the 2550 cylinder.



So in all honesty, and with all joking aside.. I'm getting a 2150- is it a small motor saw or up close to 40cc? I'm all confused now..


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## Chris-PA (Feb 23, 2013)

You won't really know until you look at the EPA tag on the back. It will either be 36cc or 42cc, because after a while they just put 42cc engines in all saws of that family. It was cheaper that way. I had a Craftsman that said 40cc on the side but it was 42cc. 

I just finished grinding on the cylinder of a well-worn 36cc engine I got in a box of spares. It'll need a ring but then I'm going to see how it runs with a larger carb and some timing advance. I bet it does just fine if the ring seals.


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## fearofpavement (Feb 23, 2013)

This thread might explain why the Craftsman saw that passed through here recently said 42cc in one place and 40cc in another.


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## Brian B. (Feb 23, 2013)

I was supposed to get that sucker this morning but now it might be tomorrow. That would sure be cool if it was the bigger motor.


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## Brian B. (Feb 23, 2013)

WoodHeatWarrior said:


> You won't really know until you look at the EPA tag on the back. It will either be 36cc or 42cc, because after a while they just put 42cc engines in all saws of that family. It was cheaper that way. I had a Craftsman that said 40cc on the side but it was 42cc.
> 
> I just finished grinding on the cylinder of a well-worn 36cc engine I got in a box of spares. It'll need a ring but then I'm going to see how it runs with a larger carb and some timing advance. I bet it does just fine if the ring seals.




So, the epa tag will just openly list the cc size? Or is it encrypted/ disguised somehow? (Thanks)


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## Chris-PA (Feb 23, 2013)

Brian B. said:


> So, the epa tag will just openly list the cc size? Or is it encrypted/ disguised somehow? (Thanks)


Yeah, it just lists it clearly as 42cc or whatever it is.


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## Brian B. (Feb 23, 2013)

WoodHeatWarrior said:


> Brian B. said:
> 
> 
> > So, the epa tag will just openly list the cc size? Or is it encrypted/ disguised somehow? (Thanks)[/QUOTEYeah, it just lists it clearly as 42cc or whatever it is.]
> ...


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## Oddjobz (Mar 13, 2017)

I just found this thread and found it interesting since I've just rebuilt a bunch of these......

All of these saws are based on the Partner 350 and 351. 
I've taken apart, and swapped parts between the Craftsman, Poulans, Poulan Pros and Jonsereds.
They all either have the 38mm or the 41.1mm piston and cylinders and they are all interchangeable.
PP220, 260 2150 2050, 2137 etc etc etc..........

If you want to upgrade any of these saws....especially the Poulans, pull out the exhaust restricter....yes that little metal
piece of junk in the exhaust port and dremel away the lip. You can also take 1/32 off the bottom and top and 1/16 to each side.

The intake can be opened up a bit also, plus you can take 1/32 or so on the bakelite carb mount.......

Note that there are 41.1mm dual ring pistons available too......yes it will fit in the poulans.


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## Chris-PA (Mar 13, 2017)

Oddjobz said:


> All of these saws are based on the Partner 350 and 351


Actually the Partner is just a renamed Poulan. 

Don't grind the lip off the lower edge of the exhaust port - it doesn't help and you risk freeporting it.


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## Oddjobz (Mar 14, 2017)

Whichever name is first is a moot point... you can be sure all these saws are assembled in the USA from parts
made in China/Taiwan and some of the steel parts from Sweden. 

I have a Jonsered 2137 sitting on the bench.... nice sticker on the back "Assembled in USA". 
The Husky Jenn Feng division is probably making the parts in its Taiwan or China factories and 
shipping to the US for Assembly.

The only danger with the bottom lip is if you go to/past the first ring.....and you have at least another 1/8 after you fully
remove the bottom lip. I've done several, not a problem. 

All of these are given CC sizes because that is what most people understand....by varying port sizes the manufacturer
can change the HP rating....but tell people a HP rating for a saw and it is lost on them..... 3.15 HP vs 3.24 HP. 
Not as marketable as 38cc or 40cc . That decimal point is a no go in marketing. 

Kind of funny since HP is a moot point in devices requiring torque........ "Hey my saw as 220ft lbs of torque.
Oh yeah, well my Stihl has 290ft lbs of torque....it can buck its way out of a pinched oak"..... when was that last 
time you heard that conversation .....eh?


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> Whichever name is first is a moot point... you can be sure all these saws are assembled in the USA from parts
> made in China/Taiwan and some of the steel parts from Sweden.
> 
> I have a Jonsered 2137 sitting on the bench.... nice sticker on the back "Assembled in USA".
> ...


No doubt some parts and materials are sourced off shore, but those are mostly US made saws, and US designed from what I've read. I don't believe Jenn Feng was bought by Husqvarna but I'd like to see any info on that. Husqvarna just bought the McCulloch brand as far as I know. 

The issues with lowering the bottom lip on the exhaust port are that it does not help to move the lower edge below the piston top because the piston still blocks it, and that the lower edge of the piston will open the exhaust port into the case at TDC - that is called freeporting. The lip helps in evacuating the exhaust gas. I have done a few as well.

Last, the whole torque vs. horsepower is a silly argument as in an engine we never discuss static torque, only torque at an rpm. Torque at an rpm is the definition of power. You can convert any plot of torque vs rpm to a hp vs. rpm plot with no additional data; therefore they are just alternative representations of the same thing. Power is what does work.


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## Oddjobz (Mar 14, 2017)

I had originally posted this over on chainsawcollectors......


99-03 Mcculloch name owned by Jenn Feng (MTD buys NA rights after that), 
The best part is that Husqvarna bought Jenn Feng in 2008......This is how they acquired the brand names.

******************************************************************************
Interesting, Jenn Feng a Taiwan company, this news report from China puts its operations in China.
Small world.
*******************************************************************************

Husqvarna buys Jenn Feng chainsaw, mower unit
Bloomberg March 18, 2008, 12:00 am TWN

STOCKHOLM -- Husqvarna, the world's largest maker of lawnmowers, agreed to buy a chainsaw and mower business from Jenn Feng Industrial Co. of Taiwan for about US$100 million.

The Huskvarna, Sweden-based company will pay US$83 million in cash up front and the rest of the price will depend on the unit's working capital at the time the deal is closed, spokeswoman Aasa Stenqvist said yesterday. Husqvarna, spun off from appliance maker Electrolux AB in 2006, has expanded in Asia through acquisitions including China's Hebei Jikai Industrial Ltd., a maker of diamond saws. The Jenn Feng operations, located in China, will give the Swedish company a wider manufacturing base in Asia, Husqvarna said. 

http://www.chinapost.com.tw/taiwan/busi ... a-buys.htm


******************************

Some of the more premium saw parts are probably made by Zenoah......which was bought by Husqvarna in 2007
http://www.zenoah.co.jp/int/company/company-outline/

*************

As for the freeporting, technically as soon as the rings pass the exhaust port, your exhaust port has contact
with the crankcase....since the seal has progressed past the port. The only thing that interferes is the piston
skirt. If your piston has a short skirt the port is open to the crankcase and yes that is bad......all the ones I've done
so far have had a long enough skirt to prevent flow through.......which is what you are referring to when you say 
freeporting......(it can also be called venting). There are several flavors of these engines around, wouldn't be surprised
if there were shorter and longer versions. 1/8 inch can make a world of difference. 

I've been a mechanic for over 40 years so I've heard many different terms that refer to the same thing.
In four strokes this same effect can happen with too long or too early a cam lobe duration or weak valve spring float.


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## Oddjobz (Mar 14, 2017)

Well, ever since the class action lawsuit in 08 consumers have been left in the dark as to just what
capacities their equipment has..... ooomphf is the ability to get the job done, and torque is what does it.
http://movingsnow.com/2008/cc-to-torque-to-hp-conversion-update/

Torque is power....I worked many years in Diesel Transport........and Torque is what gets everything moving.

But! Torque is the result of gearing... which is evident on a snowblower or anything with a transmission.

For a directly driven system like a chainsaw .......it's a different story. Your power is a direct result
bore, stroke, fuel mixture and flow volumes... at different engine speeds. When you buck a tree and
make your cut at full throttle you are using the Max HP to start the cut, but once the cut is started, it
is the torque that carries the momentum against the coefficient of the wood. (ie: wet, dry, dense, soft, hard)
Powerband is everything in chainsaws.....you can play around a bit with sprocket sizes and chain specs.
...but the oomphf is what really matters.

So to the one who started the thread......your engine size is irrelevant. Your engine power is everything.


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## dougand3 (Mar 14, 2017)

I see Partner 350 top ends 41.1mm that look like they'd fit 1990-2005 Poulans for ~$30. Thing is...I rarely have scored P&C in those saws. 

I have a few strato Poulans in boxes with scored P&C that aren't worth rebuilding with OEM top ends at $60.

Is there a Partner saw aftermarket top end for 2005 and newer strato Poulans (intake manifold has 4 bolts)?


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## Oddjobz (Mar 14, 2017)

The $30 partner 350 P&C will replace the 38mm and 41.1mm in most of the Sears 944.xxxxx models.
Mcculloch 335 435 440
The Poulan 1950 2025 *2050 *2075 *2150 *2175 2350 2375 *220 *230 *260 *Jonsered *2137 *and a few others.
(I haven't confirmed all the poulan models yet, bold ones I've done first hand)
What's the model of strato poulan....


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## dougand3 (Mar 14, 2017)

One is a Poulan 4218AVX. I did just see a Partner 842 or 742 or McCulloch 742 or 842 top end that may be it. The Poulan carcasses are at the other house. I'll compare jugs tonite.

http://www.ebay.com/itm/222370369891?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT


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## Oddjobz (Mar 14, 2017)

Yup.....these are the same. All will take the 41mm plug & jug.

POULAN PARTNER P3314 3416 3516PR 3818AV 4018 PP3516 3816 4018 4218 PPB3416 4018 S1970 + Others

REPLACES OEM PART#(S): POULAN / PARTNER 506 07 18-84 ,506 07 18-83

You can also search for: 530071884 inclu desription


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> The best part is that Husqvarna bought Jenn Feng in 2008......This is how they acquired the brand names.


OK, thanks for that. I thought they had just bought the name. It would explain why many of the Jenn Feng saws are still being sold in various places under Husqvarna names/brands.



Oddjobz said:


> Torque is power


No, this is the basic error. These terms all are very precisely defined as part of classical mechanics, but for some reason people who work with engines get them all garbled up. Torque is a measure of force in a rotational system. It does not involve movement at all, or any transfer of energy. It is just a force. Torque applied _with_ a movement does transfer energy, and the rate at which it is transfers is called power. Power is what does work, and torque does not. Trying to make a distinction between power and torque at a rotational speed makes no sense, as they are the same.

Power is the work per unit time, given by





where P is power, τ is torque, ω is the angular velocity (Torque)

What people are usually trying to convey is that you want a broad power band rather than a peaky one, and this is especially true with a chainsaw that cannot be geared in any practical way.



Oddjobz said:


> As for the freeporting, technically as soon as the rings pass the exhaust port, your exhaust port has contact
> with the crankcase


Technically yes, but practically no as there is not enough opening area to allow much if any flow. That does not happen until there is some significant opening area. I have a minorly freeported 42cc Poulan and it runs fine, but it is something to avoid. That step/lip at the lower edge of the exhaust port is a benefit as it allows for a rapid expansion of the gas volume and reduction in pressure, helping to avoid reversion. Here is one I freeported:


This is how I do them now:


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## Oddjobz (Mar 14, 2017)

Yea yeah.....angular momentum, vector, it's actually in newtow/meters blah blah blah.
Your best to not relate the schoolbook physics when looking at practical application.
KISS.....keep it simple stupid! 

For the consumer's sake. 
Torque is the power that gets things moving/moves against resistance.....ft lbs reflect the amount of force/power that can be developed.

Yes, you are correct....but your argument is pointless when confronting the average consumer. 

May the force be with you.......

(I also build computers, networks etc, when someone asks what DNS is, I don't get long winded with things they won't understand,
instead I tell them: It's the phone book for the Internet) K.I.S.S. ....get it?

******

Porting is always a risk.... easiest way to ck for danger.....take the rings off the piston, drop it in the cylinder, scribe a line
at the bottom of the port, pull the piston out and ck the distance to the bottom of the skirt. Note that the piston never reaches
the end of the cylinder when at TDC, so you get a safety margin to boot.

I've always liked to push it to the limits......your play it safe option is perfectly fine......just not for all us dremel happy nuts.


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> Torque is the power that gets things moving


OK, then KISS - _Power_ is the power that gets things moving. 



Oddjobz said:


> your play it safe option is perfectly fine


Yup, play it safe, that's me. As in a squish modded 42cc Poulan clamshell with a cut cylinder and a relocated crank, pop-up piston, plus a modified crank and filled clamshell cap to reduce case volume and help pump gas up the transfers. http://www.arboristsite.com/community/threads/reducing-squish-on-a-poulan-clamshell.273087/

Even used 3D printed tools:












It's got some porting changes and a bored carb too. I suppose you _could_ mod one further...


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## Oddjobz (Mar 14, 2017)

Ohhh, got a shiver.......that's an awesome one. Squeeeeeeze every last ft lb of 'power' out of that sucker......


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> Ohhh, got a shiver.......that's an awesome one. Squeeeeeeze every last ft lb of 'power' out of that sucker......


They are fun to play with. Sorry for giving you a hard time, I'm glad to see someone else modding them. The darn things run damn well given the humble engine architecture.


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## Oddjobz (Mar 14, 2017)

For the average homeowner they are the perfect saw. They just need to be given access to their full potential.

Just the fact that you can get a dual ring piston puts these saws in a whole new league. Get the vapors flowing
and these saws wake up........I've had great fun modding the 41.1s 

If you want to get another quick and easy squeeze of power.......try this. Gives the cylinder a Hemi affect.
Used in pocket bike racing.
I use them in everything in that CJ7 heat range....(sometimes even the CJ6 & 8 can be swapped with these too)


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> For the average homeowner they are the perfect saw. They just need to be given access to their full potential.
> 
> Just the fact that you can get a dual ring piston puts these saws in a whole new league. Get the vapors flowing
> and these saws wake up........I've had great fun modding the 41.1s
> ...


Interesting plug. 

I bought one of the 2-ring pistons on a lark. It only came with one ring, but I have another - what do you want for $6? It's got a lower piston height though, which puts the squish at 0.050", so I'll have to cut the cylinder even more than I care to. I may use it anyway just to see how it compares. I'll have to get another chassis to put it in though, and I not sure if/when I'm going to get around to building that engine. I might just keep in in case this one fails, although it's holding up well. 

Note that the 2-ring pistons are sold for the Partner saws which use the bare aluminum bore/chromed piston. That happens to be the engine I have lying around, but the Poulan Pro engines with plated bores and bare pistons are better from a durability point of view.


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## Oddjobz (Mar 14, 2017)

You can't beat hard chrome plating for durability.... Sadly, once badly scored or cracked the replacement cost of an oem is prohibitive.
The aftermarked P&C with duel rings are under $30 and you can get a 10pk of rings for under $10. I just received a 5pk of pistons I'm 
trying out......got 2 sets of P&Cs on the way. Curious to see how the Nikasil Cylinders hold up

There are a few variations of the cylinders....the Jonsered 2137 I have does not have any insert
in the port or ridge either. Different casting number also......but no doubt it is exactly the same engine as the Poulans and Sears I did last week.


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## Chris-PA (Mar 14, 2017)

Oddjobz said:


> There are a few variations of the cylinders....the Jonsered 2137 I have does not have any insert
> in the port or ridge either. Different casting number also......but no doubt it is exactly the same engine as the Poulans and Sears I did last week.


The later cylinders right before they went to strato are different, with smaller volume transfers and larger combustion chambers, and much different port timing. Some did not have the insert. They used a cat muffler too. Look at the last link I gave above for a build I did one one of these later cylinders - they can be made to run well but are at a disadvantage compared to the earlier ones. 

And some of the Jonsered 2137 are actually 46cc, but don't tell anyone as I have not found one yet.


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## Oddjobz (Mar 14, 2017)

This 2137 has the same bore, I'll have to double ck the stroke and top of the jug tomorrow. 
Jug is scrap anyway, huge score inside and I'm not going to waste time with epoxy when I have a new jug on the way.

Hmm Jonsered is often doing funny things....I have a 455 (42mm P&C) case that I was able to straight drop a 525 44mm P&C&Crank in since both crank seals
are the same OD. The 525 ended around 1986 when the 455 started. Guess they didn't want to totally re-engineer.


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## dougand3 (Mar 15, 2017)

Thanks for info, Oddjobz. The Partner 742 jug is a direct match for a P4128avx. Best price I see for a whole top end is $40. Too much for a saw that sells for $60 as a good runner. Now, if you wanted to learn clamshell rebuilding = small tuition payment.


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## Chris-PA (Mar 15, 2017)

dougand3 said:


> Thanks for info, Oddjobz. The Partner 742 jug is a direct match for a P4128avx. Best price I see for a whole top end is $40. Too much for a saw that sells for $60 as a good runner. Now, if you wanted to learn clamshell rebuilding = small tuition payment.


I find that viewpoint curious. It's a logical way to look at it if you are going to sell it because you have to make money and account for your time. But if you are going to keep and use the saw then shouldn't it just be how much capability you can get for the money spent? If you have a saw with a roached top end it is worthless as a tool. From there, what is the cheapest way to get a capable tool to use? Seems to me it would cost you $40. Add in a little time for some minor mods and you have a very capable tool for most firewood gathering and homeowner uses.

Or you could spend $60 for a "good runner" that will likely be someone else's bundle of problems.

The problem here is in assuming price in $ is a good measure of value.


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## dougand3 (Mar 15, 2017)

Chris-PA said:


> It's a logical way to look at it if you are going to sell it because you have to make money and account for your time.


My total measure on a trade in non runner. I have plenty of good runners. For someone who has no saws, your point is valid - build a good saw for personal use and learn along the way.


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