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Worked on my Jonsered 49SP today....

Discussion in 'Chainsaw' started by Dan_IN_MN, Jan 19, 2009.

  1. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

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    Worked on my Jonsered 49SP today. It started out by truing the bar. Then I thought....I should pull the muffler and see what the piston looks like. Well there is/are some scoring. The muffler port was all carboned up. So, I started scrapping and carbon got everywhere...so, I took the air hose and blew it out...not thinking about the intake ports being open to the crankcase which got the bits of carbon in it. :monkey: :confused: Now...I need to get that out of there...so apart came the saw.

    The ring was partly stuck to the piston. Piston is scored and the ring grove closed up a bit because of this. I spent some time getting the carbon off of the piston in the wristpin area(wristpin would stick on the carbon build up in the hole in the piston), ring grove, and the top. Now the ring is free to expand and contract withing the groove. Ring contact with the cylinder is a plus. :clap: I probably will replace the piston and ring some time in the feature.

    I flushed the crankcase twice with mixed gas. I'm glad I did because the gunk in the crankcase turned turned the gas black both times.

    On reassembly I took some 2 stroke oil on the crank bearings, piston, ring, and wristpin.

    I didn't do a compression check before I did the work because I wasn't planning on taring the saw down. I should give it a check after a few tanks of mix.

    I think it has more power.. it starts better and after a carb adjustment I think it idles better.

    This is probably better than the mod I mention in this thread:

    http://www.arboristsite.com/showthread.php?t=85906

    Thanks for taking a peek!

    Dan
     
  2. Modifiedmark

    Modifiedmark Tree Freak

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    Well good luck in finding a piston for a 49sp.


    Just so you know the pre epa (44mm) Husky 350 piston ring fits perfectly.
     
  3. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

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    I'll keep that in mind!

    mod-Mark

    I'll keep that in mind! Thanks for the heads up! :clap:

    Dan
     
  4. Modifiedmark

    Modifiedmark Tree Freak

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    I don't know if it's still there but a day or two ago someone had a piston and cylinder listed on ebay.

    If you think you need one, better snatch it up, there hard to come by.
     
  5. Javelin

    Javelin Addicted to ArboristSite

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    254 olympic piston will work!
     
  6. Modifiedmark

    Modifiedmark Tree Freak

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    Really? Where were you a year or so ago :)

    Second thought, I'll bet the 245 Oly pistons grow on trees don't they!
     
  7. Javelin

    Javelin Addicted to ArboristSite

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    :) I will check I might have a few left! I use to use them alot! I do not know if they are still available from efco because I am no longer a dealer with them thanks to there worthless dist. here! But that is a long story!:)
     
  8. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

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    I ran a tank of fuel through today

    I ran a tank of fuel through today. It seems like it has more power. :clap: I'll post back after a few more tanks.


    Dan
     
  9. doc874

    doc874 Addicted to ArboristSite

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    Yep your correct, been there done that worked great still got the piston, brand new minus the ring, have no use for the piston though.
     
  10. imanoob

    imanoob ArboristSite Member

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    My dad has an old jonsered 49sp that still runs great. It was our firewood saw last year until something happened with the points on it. What would it be worth? Oiler works good, chain brake works good, saw runs good, starts and idles fine, no bogging of flat spots in the power. Anyway I was just wondering if you know what it might be worth to someone? Still needs the points replaced or bypassed.

    Thanks
     
  11. spike60

    spike60 ArboristSite.com Sponsor

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    49SP's are one of my favorites; I've got 4 of them. They will hold their own with todays 50CC class leaders, including the 2153/346 and 5100S. I have customers that still use these saws on a regular basis.

    ModifiedMark is right about trying to find a piston for them. NLA for quite a while now. I second the motion about the early 350 ring working. I didn't know about the 254 Olympyk piston. Is it domed like the 49SP piston is, and is it still available?

    49SP's are pretty easy to work on, but parts are pretty scarce beyond starter springs and sprockets. There is some interchangability with Jonsered models that followed it, but I haven't needed to do that yet so I can't be specific.

    The deal with these old Jonnys is to grab any parts saw you come across, no matter how trashed it appears to be. There's always something on there that you can use.
     
  12. PB

    PB Addicted to ArboristSite

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    You can't escape yourself
    I believe that the piston and cylinder from the 50, 51, and 52 can be used on this saw. You will need each respective intake manifold though. The manifold from the 51 won't fit on the 50 or 52 or 49 so if you are buying a cylinder make sure you can get the proper intake. All of the above saws are 49cc. I have not done this personally so take it for what it is worth. I am in the process of doing this with my 51 so I can report back later.

    The 49sp takes a standard 44mm x 1.5mm piston ring. They are widely available and like others have mentioned the 350 ring will work.
     
  13. Farley9n

    Farley9n AboristSite Guru

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    I think there are some differences in the coil mounting between the 49sp and the 52's that would make it complicated to use those cylinders on a 49sp. I have had good sucess using the 52's two ring piston in the 49sp but have never interchanged the cylinders. As I remember there was a change to an electronic ignition after the 49sp's.......Bob
     
  14. AOD

    AOD Addicted to ArboristSite

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    Hmm,. thats new to me, I bought a 52 jug and slug to fix my 49, but now I see that its missing the entire ignition system. I think I am better off buying another 49 for parts and making a Frankensaw out of the two.
     
  15. PB

    PB Addicted to ArboristSite

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    Yes the ignitions are different, but the piston and cylinders will fit. The 49's coil mounts on the cylinder while the later models mounted in the recoil if I remember right. You can put the p&c off the other models on the 49, but I guess you would need the entire ignition system from the 50 series saws. Might be more difficult than finding a 49sp piston and cylinder. :dizzy:
     
  16. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

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    Jonsered 49 sp (semi pro) progress!

    Well I put a second tank of fuel into the saw today. My FIL was here and we cut a fair amount of wood and didn't run out of fuel. I think that the ring has seated because that little saw is pulling that chain better and better! I had mentioned to my FIL that I might have to replace the piston and ring. He mentioned to me after watching the saw cut. "I don't think you have to do any more work on that saw. It's running real good.":clap:

    The operation was a success! The patient lives! I didn't run a compression test before I did the work, however I'll run on soon and report back what it's at.

    Might not need another saw for awhile.....:cry: I guess that's okay.....I guess the money can go to other to(y)ols!:greenchainsaw:

    Thanks for all of your input!

    Dan :chainsaw:
     
  17. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

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    Did the compression test today....

    Did the compression test today.... What are your thoughts?:popcorn:
    [​IMG]

    While I had the plug out I thought that I would take a shot of it.

    [​IMG]

    While I had the gauge out I put in in the McCulloch
    [​IMG]
     

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