Preparing myself mentally & physically to refurb a Jonsered 70E. Any tips/advise?

I've been lurking the past couple weeks and am getting close to moving ahead on my project, so I thought I would seek some input.

My father has a vintage Jonsered 70E saw that was diagnosed by a couple local saw shops to have a faulty SEM (electronic control) unit. The saw has been sitting idle and lonely in the pole barn for almost 3 years now. I recently got more aggressive with my search for parts and found this site and the references to George Blake. George had a used SEM unit for the 70E in stock and I just received it. My plan is to repair the saw and if it runs (assuming the SEM is the only problem), do a pretty extensive refurb/overhaul of the entire saw and hand it to my dad at Christmas. He has a Stihl 026 and a Husky "some number" but I know he really liked this 70E.

I'm pretty handy, do all my vehicle work, build mtn./road bikes and do my own home repairs. The idea of disassembling a saw doesn't scare me too much as long as I have an idea of what not to do or potential problems I could anticipate. I have the original parts list (with blowups) and the owners manual to guide me.

This is what I have planned:

general cleaning
new spark plug
refurb bars (file burrs, lube)
check pull string (replace if needed)
change bar oil
new chains (or have existing ones sharpened)
clean carb (possible rebuild?)
check fuel filter and fuel line

What else should be checked and/or replaced on an early 70s saw? Any fuel additives that can be used to clean parts of the fuel system I can't get to? Any other sources on this topic I should consult?

Sorry for the length of my 1st post, but just want as much info as I can get right now. I'll continue to do searches as well.

Thanks!

check the piston out real good, you sound like your pretty well planned and prepared. if the piston looks good a new set of rings might give a bit of boost on the life.

a parts list that may help with your saw is available to download at:
http://www.jonsered.ws/IPL.htm

I would make sure that the fuel line, impulse line (if present), and carby boots and any gaskets between the carby and cylinder are in good shape. One air leak can totally ruin your finished project.

Chris B.

Sounds like fun, in addition to that listed check any rubber bushings on the unit, they might be dried up after sitting, also check rewind spring, it can rust and break after long layoff. I would put some lube directly into cylinder before cranking this unit. Question about changing bar oil? You know that it has to be added every time you add fuel mix right? Have fun.

Thanks for the great feedback and the link! I have the same schematics in hard copy form, but I had planned to scan them as well.

As for the bar oil, yes, I know it is replenished quite often. I'm just not sure what condition the current oil is in, so a change to fresh oil or a fresh fill would be good. If the bar oil reservoir does have oil in it, it is at least 3 yrs. old.

So this is my updated parts list:

Fuel line
Impulse line (?)
Carb boots
All gaskets
Piston rings
All bushings
Rewind spring
Pull string
Fuel filter
Air filter

Now the golden question is how many of the parts listed above are 70E specific and will be difficult to find? I would think that items like fuel filter, fuel line, and pull string would be pretty generic and fit a multitude of applications new or old, but I really don't have an idea.

Also, what quality bar and 2-cycle oil is recommended? I usually see Stihl brand bar oil and various 2-cycle oil brands. I know Amsoil makes good oil and have a few 2-cycle oil options. The only thing is that Jonsered calls for a 25:1 mix where this one Amsoil is designed for 100:1:

Saber Professional Synthetic 100:1 Pre-Mix 2-Cycle Oil

Amsoil usually has better detergents, etc. that this motor would probably benefit from, but I wanted to know your thoughts.

Thanks again!!!

i dont trust those 100:1 claims, as long as you tune the carb for it, i would run 50:1 like a modern saw, because the modern oils are much better at protecting than the stuff back then. i would use something like stihl, husky or a similar known brand. i wouldnt bother with amsoil.. the URL i listed earlier for the manual seems to also be a parts supplier that says he can list other suppliers, its a start if nothing else

Take two Asprin and lay down for an hour or two before starting to work on that thing.

Mc Bob.

NWCS said:

if the piston looks good a new set of rings might give a bit of boost on the life.

Click to expand...

Are rings for a 70E specific to this saw or should a good saw shop have the correct size?

Thanks!

Here is what you will need:

#1) One big bottle of scott blend, minimum 12 years.
#2) Minimum 6 beer's of prefered brand.
#3) A very nice chair.
#4) at least 3 day's recovery and a box asprin.

Oh I forgot.... Peanuts!!!!
Can't live on the good alone, must have some food too.