Jonsered 820 rebuild

[t4driller]

I've been working on a jonsered 820 with heated handles for the last couple weeks. So far I installed new crank, bearings/seals, av mounts, and made my own crankcase gasket. Also fixed the wiring for the heated handles. They were all chewed up and broken. I'm currently working on the cylinder. It's 52mm side fed transfers with windowed piston. I also have a 54mm 910 cylinder that's bottom fed transfer. I originally was going to put the 54mm top on it but after taking timing numbers and squish I decided to use the original 52mm p/c. Numbers of both cylinders are...
52mm w/out base gasket
Ex 105.5
Trans 125
In 72
Squish .023

54mm w/out base gasket
Ex 105
Trans 124
In 62
Squish is more then .050
I checked the pin to crown height and skirt length and they are both the same for each piston. So I'm not sure why the squish is so much. Both are 38mm stroke also. ( thanks redfin) .

I already started to port the 52mm cylinder. Widened the intake/exhaust. Raised the exhaust to 104. Lowered the intake to 75. Also did some work to the lowers. So here's where I'm at at this point. Any input is always appreciated[emoji4] [emoji4] pics of progress

 

[t4driller]

52mm cylinder

little port work

 

[t4driller]

54mm cylinder

I don't like how the muffler is, but it will get gutted and open the original port up or add another.

 

[t4driller]

Oh, and thank you to Ross ( esxw) for selling me this saw. It's my first heated handles saw...

 

[exSW]

I knew I did the right thing
Besides you already had the parts.

 

[jacob j.]

Looking good so far. This series of Jonsereds are a real sleeper model. They can be made to run really good with a little work.

 

[t4driller]

I knew I did the right thing
Besides you already had the parts.

All those parts are coming in handy. Only thing I need to buy for it is a carb kit and I traded for a crank. Everything else I had in my inventory. I can see why the switch for the handles wass broken. The new one is very hard to switch back and forth. Also it's right beside the handle for recoil.

 

[t4driller]

Looking good so far. This series of Jonsereds are a real sleeper model. They can be made to run really good with a little work.

I hope so. The chamber looks kinda small and with the exhaust where it's at I think it's going to have alot of compression. Time will tell.

 

[Onan18]

It is my understanding that there is a very big gain to be had by grinding out the area from the bottom transfer (make it open to the crankcase) to match the 910. This will basically turn your 820 cylinder into a (later) 830 cylinder. The early 830s and 930s used the same cylinder as the 820/920 but once Jonsered figured out how much gain there was by making the lowers open to the crankcase they took the unsold units off the shelf and updated them.

Joe

 

[Onan18]

Also a 930 is very near the top of my "Dream Saw" list.

Joe

 

[t4driller]

It is my understanding that there is a very big gain to be had by grinding out the area from the bottom transfer (make it open to the crankcase) to match the 910. This will basically turn your 820 cylinder into a (later) 830 cylinder. The early 830s and 930s used the same cylinder as the 820/920 but once Jonsered figured out how much gain there was by making the lowers open to the crankcase they took the unsold units off the shelf and updated them.

Joe

Hmm, interesting. I'll have to find pics of a 930 cylinder.

 

[Onan18]

This may help (not my video).

Joe

 

[t4driller]

This may help (not my video).

Joe

I always like watching his videos. Very informative. Guess I know what to do now. There's gonna be alot of aluminum on my bench.

 

[jockeydeuce]

Great build! Sure glad to see that crank go to a good home!

 

[t4driller]

One side cut in. Hands are numb

 

[t4driller]

Did some more grinding. Got everything pretty much finished up. In the pics I still need to put bevels on, Polish exhaust, and get the broke off exgausr bokt out of the cylinder. Final numbers are
Ex 103.5
Trans 122
In 75.5

I'm gonna try and get most of it t9gether tonight and split the muffler to get the baffles/ deflectors out. Think I should do a timing advance also??

 

[t4driller]

all back together and running... the original module was bad so I switched with a new sem module I had. Fired up on the 2nd pull. Now I just need to find a bar for it. I have a 24 total bar that I thought fit it but it does not. Bar slot is a hair to small.

Couple questions I have... do they make an adaptor to run a stihl bar? And how long does it usually take for the heated handles to warm up? I only had it running a couple minutes to get the tune close.

 

[jockeydeuce]

It takes very little file time to make a regular D009 Husky mount fit. It's only a mm of material.

 

[exSW]

Did you test all the circuits before you reassembled it? The specs are in the Husky thread. Tor walked me through it for my 266.

 

[t4driller]

It takes very little file time to make a regular D009 Husky mount fit. It's only a mm of material.

That's what I was thinking of doing.. I'll do that tonight so I can run it tomorrow.