Big old Jonsereds...

[weimedog]

So the 61 is complete..runs well. On to the next project. Either going to pick apart a Old Jonsered 920 or a newer Jonsered 2094. Muffler mods and light cylinder mods possible I guess. Any here have any interest in those old monsters? Any pics and historical knowledge to post?

I have a few. Really like them but they are heavy.....and old.

A pic of a couple that might be victims....From left to right...920, 2094, 820. The 2094 is warmed over for GTG's and the other two are essentially stock working saws..I use them!


Some raw materials....

Big Jugs....2094 & 2095 Style


Big Jugs 920 & 930 style (posted before)


New after market pistons for 920 & 2094 (Same piston as a 394 Husqvarna)


Yet another..a 920 I just stuck together last week..stock thru and thru.


So possiblilities....convert the 820 to a 930 top end. Take the stock 920 and convert to a 930 both with cleaned up ports & muffler mods. Actually hope some of you folks post projects as well..especially if you have one of these!

[Al_Smith]

  Actually hope some of you folks post projects as well..especially if you have one of these!

I've got a couple in the works once the mood strikes me .However I think I might have ADD because after about 5 minutes of fumbling around trying to figure out of how to post pics on different forums I give it up for a lost cause . I'll take a chill pill,drink a toddy or three and give it the old college try once again though .

Oh come to think about it I do have around 4-5 folders of the soup up jobs I have done .Plus resleeving an old Mac which I think I'm the only one who has ever shown that one on the internet .

[weimedog]

PM me and I can help you post pics...this evening. I think your stuff would be awesome! So lets just figure out a way to post...worst comes to worst just email me the pics and I'll post the attached files for you,

[Al_Smith]

  Well evidently my chill pill didn't work . I gave it the old college try though but tomorrow is another day .

[Corley5]

My old 2094 is overhead in the woodshed.  It blew a crank seal and I needed a saw so I got a 395XP.  Maybe someday I'll get it fixed    It was the 1st my local J-Red dealer sold.  He was going to make me a deal on a 930 but I knew what I wanted 

[Al_Smith]

A seal replacement is pretty easy to do .If you have the J-red part number chances are I can cross reference it unless they bastardized them like Stihl .

[HolmenTree]

My 1st logging saws were Jonsereds: 621, 80,801, 90, 910, 920 and lastly a 630. My older brother had all these plus a 111. I even have all the issues of Chainsaw Age magazine's Jonsered 111 hotsaw project from the early 1980s. That saw now resides in Wayne Sutton's chainsaw museum in Amboy Wash.
My favorite big Jonsered was the 910, very lightweight and I believe had more power then my newer 920. Its been 30 yrs since I ran these saws but I remember well their good power and reliability.

Willard.

[weimedog]

Any change you can have that saw age article scanned? (I have a scanner if you have a way to get it here)

 As far as the 910-920 power difference (and power back in the 930's) I'm sort of developing a theory....ever notice all the Jonsered cases have windows for transfers cast is? The 920's cylinders don't take advantage of that but the 930's certainly do. I have to wonder if a 910's cylinder does. I've posted pics of this around before...but will for this again.

920 Cylinder on the left, 930 on the right, a 920 case on the bottom.

[HolmenTree]

Has been yrs since I had a Jonsered apart but if the order of photos you show are correct then the 930 cylinder will mate up perfectly with the 920 case. The Stihls didn't have that lip sticking out of the base and were easier to mill then the Jonsered/ Husky.The 910 was different design from the 920 and may have been like the 930 cylinder.
I have never been able to post pics on this site but I'm sure I can somehow scan the Jonsered 111 project saw pages easy enough to you , I'm at the moment in the big city at my inlaws, will be heading home tomorrow. I'll PM you when I get back home.

Willard.

[weimedog]

My old 2094 is overhead in the woodshed.  It blew a crank seal and I needed a saw so I got a 395XP.  Maybe someday I'll get it fixed    It was the 1st my local J-Red dealer sold.  He was going to make me a deal on a 930 but I knew what I wanted 

Those old 2094's are pretty nice old saws...I really like them. They had some serious compression stock..power too! I don't see too many that survived the logging world though. Think they were a little too hot.

[Spike60]

910's do have the case cutouts and the open bottom cylinders. Open port actually. There are some other differences that prevent parts swapping between the 910 and the 920/930. Haven't run my 910 in a while; maybe I'll bring it up next month. I also have an extra 910 P&C that we can compare to the 920 and 930 examples you have.

Looking at the differences between the fully closed 920 and the open bottom 930, we see the same type of change that was made when going from the 670/272XP to the 2171/372XP. So, it seems they learned something with the 930 that was later incorporated with the 2171/372.

Power wise for the 900's, the 930 was tops IMO. Both of mine will outcut my two 920's and my 910.

[weimedog]

More true knowledge! Glad you took a look around! There were some questions on that other thread relative to Husqvarna 61 thru 272XP series saws you might address as well.

I also have to wonder if what HolmenTree observed with the 910 t0 929 series was exactly the difference in those windowed vs. non windowed cylinders...and why your 930 isn't afraid of my 2094! On this project think a 930 cylinder is going to find its way on a 820 or 920 so we can compare.

[Spike60]

Might as well go with the 930 style since you've got some of each. You've been running enough examples of this family of saws that you should notice any difference.

What pistons are you using? I'm not a big fan of the thin ring stuff.

[quietrangr]

I had those old Jonsreds, too. A couple of 920s, but before that a 90 that pull started like a V8. You better dropstart  that sucker about 90 miles an hour or it would just buck back at you. Then when you shut it off, the rope pulled into the housing with a big thwack. You had to replace the starter rope every couple of weeks. I don't remember if they ever came up with a fix for that.

[weimedog]

I don't believe they did! (have a fix) The 2094 continued the tradition! Then they put a compression release in...the 2095's I believe all had that compression release. (Sawtroll or Spike60 will know for certain)

All mine are even worse yet as they don't have their base gaskets..just 1194. I am contemplating sending two cylinders out to have a person with better machining equiment than I add compression releases..one to a 2094 and one to a 930 cylinder. The 2094's pull start is flimsier yet than the 920's I would guess that had to be a weak spot for them! Fortunately I have two spares for mine.

What is the possibility than along with really high compression, their stock timing was a little too far advanced on the 920?

[Al_Smith]

You better dropstart  that sucker about 90 miles an hour or it would just buck back at you. Then when you shut it off, the rope pulled into the housing with a big thwack. You had to replace the starter rope every couple of weeks. I don't remember if they ever came up with a fix for that.

Not to skew the subject but I had an SP 81 Mac walk the rope on me once .That was the very last time I ever drop started that saw BTW .It's kind of a wake up call when 28" of bar goes wizzing past your ear . Lawdy if it would have started they'd be calling me one ear Al by now .

Now perhaps the problem in some cases could be a worn bushing on the starter rope reel .I experianced such a thing on a 2100 Husqvarna and repaired it by fabricating a brass bushing to replace the worn out nylon one .

[HolmenTree]

I had those old Jonsreds, too. A couple of 920s, but before that a 90 that pull started like a V8. You better dropstart  that sucker about 90 miles an hour or it would just buck back at you. Then when you shut it off, the rope pulled into the housing with a big thwack. You had to replace the starter rope every couple of weeks. I don't remember if they ever came up with a fix for that.

My 1970s Jonsered 90 had a decompression button in the top cover. The Jonsered's rubber starter handle helped ease the rewind kickback as well.

Willard.

[quietrangr]

That might have been a later model. They probably put in the decomp to cut down on the number of dislocated shoulders. And don't try cranking that hog between your legs.

[weimedog]

Working the 920 "Test Mule" today..the one that going to get surgery after Kevin's 357/359 gets done.....Stock 920 with 28inch Oregon & Stihl 3/8 chain. Was a Beech with the top dying off and making widow makers...decided to pro act vs. have in on my Sugar shack..what better way to test a saw! Have to go to work..tomorrow the 61 gets to limb & block the top half...

(Notched the far side, bore cut 3/4 side to side but bar wasn't long enough even with the notch to get out the back...started back cut saw I was a bit off...took a second cut from back and once 12in or so in put in a wedge & cut to hinge & then wedged it over...it wasn't certain which way it wanted to go..needs some persuasion.)

[HolmenTree]

That might have been a later model. They probably put in the decomp to cut down on the number of dislocated shoulders. And don't try cranking that hog between your legs.

Yep those old Jonsered 90s had kick alright and you couldn't kill them. My 90 was a 1978 and had the decomp. But you want to see compression kick my Jonsered 80 sure had some. One of my favorite Jonsereds, a little bit lighter and almost as much h.p. as the 90, with its silver top it was a beautiful old classic saw.

Willard.

[HolmenTree]

910's do have the case cutouts and the open bottom cylinders. Open port actually. There are some other differences that prevent parts swapping between the 910 and the 920/930. Haven't run my 910 in a while; maybe I'll bring it up next month. I also have an extra 910 P&C that we can compare to the 920 and 930 examples you have.

I did a little research for you Jonsereds fans. The 920 replaced the 910 in 1982 aimed for the west coast market. The man who designed the 920 and 820 was senior project engineer Niels Hartz at Electrolux Motor AB. The new features over its predecessor the 910 are: totally new handle system, new crankcases which provide better fuel tank isolation, a new venting system for the fuel tank, a new clutch, completely redesigned piston and cylinder with new porting, relocated ignition triggering mechanism, new crankshaft and a anti-kick brake.
A good quote I like from Hartz was: "The whole chainsaw is a compromise. You fix one problem and you create another. Sure you could design the 'perfect' chainsaw, but it would weigh 40 pounds!"
From this 1986 press release he also said future chainsaw technology will have on-board computers.

Willard.

[isawlogs]

  I have a 630 that is in need of a top end, where do I start to look for one 

[SawTroll]

My 1970s Jonsered 90 had a decompression button in the top cover. The Jonsered's rubber starter handle helped ease the rewind kickback as well.

Willard.

I believe they all did.

[Spike60]

  I have a 630 that is in need of a top end, where do I start to look for one 

This one is still available, and because the set was also used by Husky, (162), any Husky dealer can get it. Not sure if it's still available from Tilton, or for how long.

Part number is 503 517 502; price is about $250.

A 266XP top end will also work, and there may be some less expensive aftermarket options out there. Any other top end in this family will work, but as discussed in Weimedog's thread, there are some carb/intake changes necessary to fit them.

[SawTroll]

  I have a 630 that is in need of a top end, where do I start to look for one  

This one is still available, and because the set was also used by Husky, (162), any Husky dealer can get it. Not sure if it's still available from Tilton, or for how long.

Part number is 503 517 502; price is about $250.

A 266XP top end will also work, and there may be some less expensive aftermarket options out there. Any other top end in this family will work, but as discussed in Weimedog's thread, there are some carb/intake changes necessary to fit them.

Yes, that saw family is really hard to get a grip on all the facts about, as there were several different top ends and carbs, then there also were different intakes, top covers + variants of the case - and who knows what more.....

[Cut4fun]

The 630 thin rings can still be found too. 

I'll put my ole stock 65cc Poulan against a stock Jonsered 630.

[weimedog]

So the 920 project begins...have the two test mule saws, a Jonsered 820 and Jonsered 920 both stock to start with. I'm going to up grade the 820 with a cylinder cut to match the case window's...and intake widened slightly and lowered a small amount along with the transfers & exhaust cleaned out. Only change to stock timing is lowering the intake a bit...then we can run them back to back to see if those mods helped or hurt! (Actually a better plan is to run it with Spikes really clean 930...where those cylinders came windowed from the factory I believe. AND his is a very nice and clean sample of that model that also has other improvements such as the intake filter & filter horn)


Stock


roughed out...

[weimedog]

To thin or thick ring sould I go?


Have an Episan thick ring after market piston and two thin ring OEM used but good Jonsered pistons....I'm leaning towards the Episan...anyone have good things to say about those thin ring pistons?

[Al_Smith]

Less ring drag .FWIW about all newer model auto engine use skinny rings .Also why some people only run one ring in a cookie cutter .

[weimedog]

Sort of wish I had a better camera so you all could see the quality of the episan vs. stock...I have to say the aftermarket slug is pretty well made!

[HolmenTree]

My older brother raced his Jonsered 80 back in the 1970s with sucess against much larger saws,along with pulling the base gasket he also pulled the bottom ring and ran just the top ring. She was a real screamer.

Willard.

[SawTroll]

To thin or thick ring sould I go?


Have an Episan thick ring after market piston and two thin ring OEM used but good Jonsered pistons....I'm leaning towards the Episan...anyone have good things to say about those thin ring pistons?

.....

Just a thought - why not use the thin ring ones as long as they last?

[weimedog]

To thin or thick ring sould I go?


Have an Episan thick ring after market piston and two thin ring OEM used but good Jonsered pistons....I'm leaning towards the Episan...anyone have good things to say about those thin ring pistons?

.....

Just a thought - why not use the thin ring ones as long as they last?

Nothing like common sense....actually might as well! Other wise those perfectly good pistons will just sit on a shelf as I continue to rationalize my way into after market stuff!

[HolmenTree]

Weimedog when you remove material from the cylinder's base spigot you are increasing crankcase volume which hurts performance gains.
You will have to stuff your crankcase with enough material to compensate what you took off the spigot.

Willard.

[weimedog]

Thanks for the heads up! ...There is a bit of history here as well. The 930 J-reds came with a cut outs at the cylinder base and everything else being about the same (except intake horn & filter) had a significant power gain. So two things that will be tested here is:

1) replicating the change the 930's had on the 930 cylinders..does that add power? (Actually I basically matched the windows on the cases where the 930's were just milled straight (they stuck an end mill in and made a short linear cut..that's it)..I'll post the pics again)
2) Three other mods are in play. Increase intake duration, slight increased in compression, and increased x-sectional area of the exhaust, and slight mods to the intake track.

Then I will test side by side...if I went backwards...oh well...

(I will degree it at some point...just starting this one.)

So pic repeat & compare:

The cylinder on the left is the one I hacked at, the one on the right is the stock 930 cylinder.

After the hacking:


What isn't shown is the widened & enlarged exhaust & widened & lowered intake. If it doesn't gain..I toss the cylinder and do something else! Have two more...the experimental one has a chuck out of the top fin and its the guinea pig..if things work..I have a nice cylinder I will replicate the mods to...If I gain nothing..I'll build it back to stock and be happy!

[weimedog]

Two pics..First is the 820 right after tear down. I had stuck it together this time last year with a "Golf" brand piston...just for kicks more than anything else. Never heard great things but never heard any bad things either about those after market pistons..so I bought one and put it in. It ran for the summer as my big saw. Ripped a lot of pine lengths for barn timber and blocked the larger timber for firewood. More use than a "Home owner" would give a saw, less that if I had used it as a primary saw (that honor moved from 455, 351, to 365 Hybrid this year) ; much less use than a pro. But two things are quite clear. First is how clean the Bel-Ray H1R burns (Almost no ash) and the entire inside had this "blue" film of oil..REALLY nice to see! This is typical for my stuff. Has been for 25-30 years since I learned how to deal with synthetics. The second is that golf brand aftermarket is perfectly happy in there. I had posted about this at another place, I had to file a "chamfer" on the inside of the skirts so it would clear the crank halves! The casting is much thicker than stock in the piston skirts. Also what isn't seen is on the top ring, at the gap, it was pretty dark on the top ring. No marks on the cylinder but wonder if that end gap was a bit big...didn't measure as the focus is on building the 920....

Golf Piston after a year of farm service:


Typical job for the 820 this last year:


The next is the difference between the 920 cylinder going on, and the 820 comming off!
920 on the left:

[weimedog]

Also going to first try one of those "thin" ring OEM pistons before running the episan. AND I found out you HAVE to run a base gasket with the stock piston as there is a slight interference in the combustion chamber. Looks like when they final bored this cylinder during manufacturing, they didn't get all the way to the top on the intake side and there is this .010 - .015 step right before the combustion chamber that interferes with the top of the piston. Tempted to take the other "OEM" thin ring piston I have and cut a .015 x .020 clearance chamfer around the top edge & take out the base gasket. Might be a candidate for a "pop up" as well.

[weimedog]

Reassembled the modded 920 cylinder on the 820....ready to test:



NEXT Big Jred Project: Have to fix cover or get different one & helicoil bolt holes for the cover. Also need an on/off switch...details details. This one is a late model 80 (serieal No. 491015) with a 90 top end....but this will be AFTER a little Husqvarna project..

[Spike60]

What color top came with that saw? Silver or black? Rather than an 80, I think it might be an 801. 80's had the cylindrical style air filter that was used on the 621. I probably have an extra black top cover. The silver covers I have a for 621's, which are a bit narrower and don't fit. But since you've got the 801/90 air filter set up, you have to go the black route. But, as you know, I have a few cans of silver paint.............

[weimedog]

Definitely the black top version with the ignition related stuff attached to the cover.


BTW fired up the "820 to 920 project saw" last night..and it runs well....need to put it in some wood to see if the initial impressions are carried into something real. It has much better throttle response and revs higher no load vs. the stock one I put together a couple of weeks ago...side by side.

[weimedog]

Update. The "slightly modded" 920 is now a mature functional saw. Its also a very strong saw. I've got several hours on it and it starts reasonably easily for what it is, runs cool, doesn't vibrate out of your hands,  nice brown plug,  doesn't leak gas or much bar oil, oils nice, chain brake NOW is on and works....etc. SO it's now in farm service.

The 80/90 isn't as happy a story. I tore it down and found a few tough problems to solve...any ideas appreciated.

1) Inside the tank the paint is disintegrating. (Had this on a 70E) as well) So it has been sucked into the fuel filter, fuel line, and ultimately clogged the screen filter in the carb..the saw apparently went lean and had a partial seize hence it came to me for repairs! THAT wasn't bad. I pulled the cylinder and scuffed up the piston & cylinder and put things back together. (Rings were fine) the compression went way up and things were looking even better becasue it had a nice hot blue spark! Could work around the paint in tank thing for a show saw.

2) In the process of putting things together, I discovered a little play in the ignition side crank bearing or so it appears. About a full .010 in. BUT when I started looking and my stock of parts, it looks like almost all the spare 80 / 90 cranks I have are corroded at the bearing contact point. That's three I have the same way. SO maybe that's what happens when they sit. Or maybe that's a weakness in the material selection on those saws. So I'm beginning to wonder if the play I feel isn't a bearing but actually the crank.

So...do we split the cases and see? Or just get it to run and don't run it often! (Pics will follow..I have a ton but it takes time)

[weimedog]

The Finished 920 with some plastic & cosmetic upgrades:

[weimedog]

The 90 project snap shots...

First..looks clean! The...carb screen clog, the hurt piston, piston cleanup and then cylinder clean up! (Can't show bad bearing or crank issue yet)

[weimedog]

One thing that strikes me as interesting is LOOK at those transfers! That cylinder is where we eventually got to with the 920 after bringing it to 930 specs plus or minus a little! Bet those Jonsered 90's were very strong saws! Wonder what the bore & stroke are vs. the 920. The intake is also cleaner than a 920 and more rugged in that it doesn't have that anti vib system inspired rubber boot that the 920 has. I think this saw or one like it might be fun to bring back to life...and maybe even mod a bit. Turns out in the spare parts bin I have a 80 bottom end, a 80 and a 90 piston....and maybe cylinders. The covers will have to trickle in over time I guess...

90 Cylinder Stock:


Modded 920 Cylinder:

[simplicityguy92]

do those 920s cut good im looking at buying a couple

[weimedog]

If you are going to build a business or start your career, I wouldn't choose them for a variety of reasons. Big heavy old saws. the standard 920's cut "OK" about like a 385 only a lot heavier. More torque than top end power.  Parts are hard to find. Bar mount is an odd size..(10mm). Weight. OK power for that weight..in their day, but not in today's world.

Having said that, For a guy like me they are perfect. With the 930 cylinder they cut very well, more like the 89cc class saw they are even in today's world. Still heavy for commercial use. If one of those saws is a "backup" with things like the ignition and intake boot, pull start, and chain brake in good condition, you could use them to earn a modern pro saw to put food on the table.

As a Jonsered collector of sorts, I love mine because I was able to mod them to modern levels of power and tweak and tune them to be a real functional big saw for my farm. That's my recreation, but I have a pile of saws as backup should I need work done in the mean time. I've got lots of parts saws to keep them going with as well. (Not going to part with any of it though) The attraction for me is they are a bit of an anomaly, easy to work on, they are Jonsereds, and mine are in fact fully capable of cutting with any modern pro saw of that size (90cc class saws)...maybe not weight yet but they are still evolving.

So it depends on what your plans for them are. But my first impression based on your stated age and presentation is no. Find a current "in production" saw like a 385XP or MS660.

[weimedog]

BTW I guess I never really did say much about how the 920 project saw came out other than it was functional. I did get the chance to run in public after a few hours of work/tweaking/tuning, brought it down to Spike's a few weeks ago, first blocking some oak, and then quartering (noodling) those blocks ...where it did a fine job. In fact its an animal power wise! I was very surprised at how much was gained by the mild porting (effectively grinding the stock 920 cylinder to a 930 configuration) vs. the stock 920..night and day! THEN yet again at another mini GTG where a modded 385XP decided to pick a fight with my 920....figured it would be close..but it wasn't. The 920 had both the power to allow me to lean its SEMI CHISEL chain and chain speed to run thru the test log faster head to head than that modded 385XP..(Actually that's not really fair, the 385 ran like a crazy thing but so does the modded 920..with a few more cc's) Either way it's an impressive for an old saw in its current form.

Photo Sumary of mods:
Cylinder with transfers ground to 930 configuration more or less (windowed to match the case windows):


Muffler Mod actually inherited from the 820 I started with and my typical mod, muffler was split, all internal baffles removed, a 3/4 tube inserted at the corner by the chain brake, and all brazed back together again. A pic of it "in process" roughed out.


SO My suggestion is instead of replicating this "cosmetically challenged" (ugly) transformation..find a 930s! Then you will have all the good stuff this one does plus it would be pretty as well!

Now back to the 90 ....more to come as we decide its fate ro to switch over to the 80 mystery saw...

[Saw Dr.]

Hey Walt, I have a 920 apart now (has been forever.)  Would you suggest I drop the transfers into the case on mine as well?  Did you do any other port work?  Was yours an NOS or Episan piston?  I have two pistons, but they're both pretty loose in the cylinder I have.

[simplicityguy92]

with alot of tork they seem like they would be a not bad rippings saw for log breakdown

[weimedog]

Hey Walt, I have a 920 apart now (has been forever.)  Would you suggest I drop the transfers into the case on mine as well?  Did you do any other port work?  Was yours an NOS or Episan piston?  I have two pistons, but they're both pretty loose in the cylinder I have.

Check your PM inbox...I would measure the pistons & inside of the cylinder to see which is worn. Hope its the pistons! Cutting the transfers to effectively copy what Jonsered in fact did with the 930 did help BTW. Episan's  are nice looking Pistons. I would have no problem using one..with OEM wrist pin clips.

[weimedog]

with alot of tork they seem like they would be a not bad rippings saw for log breakdown

Very true. I used my 820 for exactly that. (Then built it to a 920) The one thing that was a bit of an issue in my first built of the 820 was I used that soft yellow fuel line for the pulse line. That was a mistake! It melted & shut off the saw. SO back to that older style hard black line and it never melted again.

[HolmenTree]

Those older 'sered's came in different sized piston cylinder matchs "A" "B" "C"

Willard.

[Saw Dr.]

Along those lines, does anyone know if the Episan pistons are sized for the A, B, or C cylinders?  Pretty sure I have an A here.  (too lazy to go look right now...)