Lets build a saw together

[The Shooters Apprentice]

I've been working on my own saws since I was a kid, but I've never done a full ground up build. the most advanced thing Ive done was install a big bore kit on a MS361.

But for the sake of always wanting to learn more from people more knowledgable then myself, and maybe to create a instruction manual for future builders, I figured I would start a thread and document my journey.

The saw on the table is a Jonsered model 625. Its in rough shape, with a poorly done fuel tank repair, and a few other things. It would turn freely to TDC, and then not go past that. Pulling the muffler revealed the cylinder looked like it was full of grit. I pulled the cylinder and found these weird crystals in the top and bottom end. The piston and ring actually look ok, but I'm going to need to split the case to get it cleaned, and if I'm going to go that far I might as well build it a bit.

It's my understanding that the 625 is pretty much the same as the model 61, which means I should be able to convert it to a 52mm piston and cylinder to make a 272 wanna be. If I'm going to do all that, might as well port it just a bit as thats something else I've always wanted to play with.

So, first things first. Splitting the case. Has anyone built a case splitting tool, or done it without one, or do I need to buy a splitting tool?

I don't have a photo of the saw before I took it apart, but I do of the weird crystals.

 

[The Shooters Apprentice]

It was about 0 out by the time I got with other projects today, but did take a few minutes to strip the saw down some more. I noticed its missing the muffler bracket normally seen on 266s, but maybe the Jonsereds didn't come with one.

This one has a two piece ignition module, which I don't remember seeing on the 266, but I've never looked that close I suppose.

Included some photos of the ugly handle repairs. It doesn't really effect operation, but it bothers me. 61/266 handles are cheap so I'll probably order one and see if it fits.

Probably be a bit before my case splitter gets here. I still need to figure out what cylinder to order. I was just going to order a farmertec 272 cylinder and piston, but thinking about maybe doing something different with the piston if I can figure out what else fits.

 

[sean donato]

Those crystals are from water in the case. Find the same goo in a carb with water logged fuel.

 

[The Shooters Apprentice]

Those crystals are from water in the case. Find the same goo in a carb with water logged fuel.

I’ve heard they could be from that, or fuel stabilizer that’s gone bad. Either way, gives me a excuse to build this saw. I’m trying to desire right now on what set up I want to do and no one is giving much input. Definitely going 272 to end, but not sure between a cheap jug and piston, or maybe putting a 372 piston or Stihl piston in it, or just buying a hiway pop up kit.

 

[J D]

I've seen those crystals plenty on mag/ally left in a damp environment. Probably want to check the case over for rot, especially around the mating surfaces.
I think the done thing is to put a 272 piston in a 372 cylinder... if you go the other way it will probably be a lot of work for not a lot of gain

 

[The Shooters Apprentice]

I've seen those crystals plenty on mag/ally left in a damp environment. Probably want to check the case over for rot, especially around the mating surfaces.
I think the done thing is to put a 272 piston in a 372 cylinder... if you go the other way it will probably be a lot of work for not a lot of gain

Maybe I do have that mixed up in my head

 

[sean donato]

I have no helpful comments in a 70cc saw, never been my thing. So I'm just following along.

 

[The Shooters Apprentice]

I have no helpful comments in a 70cc saw, never been my thing. So I'm just following along.

This is my first time messing with a 2 series saw. My dad had a 266 and a 272 when I was a kid and he always said the madsens modified 272 was the best felling saw he ever had. I learned how to run saws on that 266 at around the age of 12 with a 32” bar on it. But, I’ve never really worked on one.

 

[The Shooters Apprentice]

I can’t find my gear puller, but I did pull the oil pump and the bearings are chock full of that crystallization as well. I really need to get this case split and see if it’s salvageable.

 

[Sepia]

The 272 piston/cylinder is a direct bolt on. The air filter cover will not fit snuggly when attached to the top cover as the 272 spark plug angle means the spark plug sits higher and will contact the air filter cover and prevent it from seating in place. Also, when swapping to a 272 cylinder you will need to use the 272 intake tract and bolts. 266s all had 2 piece ignitions as far as I know. You could bolt on a 266XP cylinder/piston and the filter cover should seat properly as the 266 spark plug will sit lower. That would essentially turn your 625 into a 670 and would be a very good upgrade. Again you will need the 266 intake tract as far as I know. If shopping on ebay beware that a lot of the 266XP cylinder kits are actually 272 kits - just have to pay attention to the bore size and intake configuration. Since you are splitting the cases, you will need crankshaft bearings. Any brand name 6202-C3 bearing will work well and are cheap. Aftermarket crank seals are also cheap and I haven't had any problems with them yet. I would stick with an oem piston bearing though, and oem piston pin and circlips. An exception to that may be the meteor piston kit which is pretty good quality.

 

[The Shooters Apprentice]

The site was being glitchy earlier and wouldn't let me attach the photo of behind the oil pump.

 

[The Shooters Apprentice]

The 272 piston/cylinder is a direct bolt on. The air filter cover will not fit snuggly when attached to the top cover as the 272 spark plug angle means the spark plug sits higher and will contact the air filter cover and prevent it from seating in place. Also, when swapping to a 272 cylinder you will need to use the 272 intake tract and bolts. 266s all had 2 piece ignitions as far as I know. You could bolt on a 266XP cylinder/piston and the filter cover should seat properly as the 266 spark plug will sit lower. That would essentially turn your 625 into a 670 and would be a very good upgrade. Again you will need the 266 intake tract as far as I know. If shopping on ebay beware that a lot of the 266XP cylinder kits are actually 272 kits - just have to pay attention to the bore size and intake configuration. Since you are splitting the cases, you will need crankshaft bearings. Any brand name 6202-C3 bearing will work well and are cheap. Aftermarket crank seals are also cheap and I haven't had any problems with them yet. I would stick with an oem piston bearing though, and oem piston pin and circlips. An exception to that may be the meteor piston kit which is pretty good quality.

I had been thinking about just getting a aftermarket airfilter cover as I'm pretty sure all the aftermarket ones are 272 covers. I was aware of needing the use the carb set up off a 272, and those parts are available as well. I wouldn't be against a 266 upper, but am a big fan of the 372s and figured I'd go bigger on this saw.

 

[Sepia]

I wasn't aware there were aftermarket filter covers available for the Jonsered 625/630/670 saws. If you want to split your cases without a puller, remove all the case bolts and heat the bearing pocket with a propane torch or heat gun and pry the cases apart carefully. The bearing will usually slip out of the bearing pocket without too much effort once the pocket is hot enough.

 

[The Shooters Apprentice]

I wasn't aware there were aftermarket filter covers available for the Jonsered 625/630/670 saws. If you want to split your cases without a puller, remove all the case bolts and heat the bearing pocket with a propane torch or heat gun and pry the cases apart carefully. The bearing will usually slip out of the bearing pocket without too much effort once the pocket is hot enough.

I don’t know if just the air filter cover will fit, but I believe the entire 272xp top cover will fit on there.

I may try heating the pockets and seeing if that case will split, but I still need to get the flywheel off as well

 

[Sepia]

For the flywheel, loosen the flywheel nut until it sits flush with the end of the crankshaft, Put a flat blade screwdriver between the back of the flywheel and the case and twist while at the same time tapping on the end of the crankshaft with a brass hammer. make sure the screwdriver is prying under the thick part of the flywheel and don't force things. Usually one or two good raps with the hammer will pop the flywheel loose.

A 272XP top cover won't bolt onto a 266se/xp crankcase because the bolt spacing is different. If you have a single coil crankcase you are likely ok, but if your crankcase is the dual coil style, there is a good chance the 272 top cover won't bolt on. I have heard of people drilling and tapping new holes in the crankcase for the 272 cover, but there isn't a lot of "meat" there for threads. Something to keep in mind when tightening the top cover screws.

 

[The Shooters Apprentice]

The coil on this one is a 2 piece, so it may very well not work with a 272 cover. Im not a expert on these saws. I assumed it would be like the 365 vs the 372 where the only real difference is the jug.

As far as the fly wheel goes, I tried that first with a hammer and prying on the back and no luck. I found my gear puller today, and I can't get it on the flywheel on this saw, so I built a puller from some stuff I had laying around. Hitting the bolt on the crank with a small electric impact in short burst then hitting it with a hammer, and adding heat and no luck so far. Got it soaking in kroil now and will give it another go after a bit.

 

[The Shooters Apprentice]

Let the Kroil work its magic for awhile and went out and hit it with the impact and hammered on it with. 4lb sledge a few more times and when she finally popped it sounded like a gunshot. bearing on that side is very rusty. My case splitter wont be here till next week so after a bit I think I am going to try splitting the case with heat, but honestly don't have much hope that it will work with how tight that danged flywheel was.

 

[Sepia]

Glad you got the flywheel off. Looks like it was practically welded on there lol. I've found heating the pocket to around 270 degrees or so will expand the pocket enough for the bearing to drop right in with no pressing, so you might find it splits easier than you think.

 

[The Shooters Apprentice]

I tried heating the bearing pockets and hammering on the crank ends and nothing. Tool's should be here soon so I'll just wait till the tools come in.

As far as the cylinder goes, I did some looking around and found some kits from Little Red Barn that are a 52mm kit for the 670. I had posted on the Jonsered thread about this project and someone had said to try finding a 670 cylinder and piston so that I could use the original carb.

The kit I found seems to use the 272 carburetor set up, and just has the added nipple for the for the impulse line, so Im getting they modify the 272 kits for the impulse. Cost was about $160 and comes with the intake block and bolts.

However, I was planning on using a 272 carb as with how rough the rest of this saw is, I'm guessing the carb is junk too. Plus the 272 carb is bigger, and if I'm adding more CC's might as well add more fuel and air flow.

 

[The Shooters Apprentice]

My case splitter came in today. Took more effort then I expected to get them separated, but the cases look good. The bearings are toast. Don't turn freely, and they sound/feel gritty.

The crank also concerns me a bit. The bearing turns free, doesn't make any noise, and seems tight, but there is definitely some blue, and there is a slight groove where the bearing rides on the flywheel side.

I need to get parts ordered for it now that I know what I'm dealing with, maybe tonight. The LRB kit will cost me more then a highway pop up kit, and I can get all the parts needed to fix the saw for that same money if I go with Farmertec parts, so I need to make up my mind and get stuff on the way.