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Thread: Ryobi strimmer

  1. #1
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    Ryobi strimmer

    A fool borrowed my strimmer. He returned it this morning saying it would not start.
    It would not start for me either so I did the ilusual checks. Good spark, getting fuel but very low compression only 5 bar.
    So i opened out engine and found this:


    I conclude the fool ran my strimmer on unmixed petrol.
    Rings are seized in the grooves.
    Is this fixable folks?
    Of course one cannot source engine parts for a Ryobi.
    Drives a Smart Cdi - 65 to 85 MPG

  2. #2
    Join Date
    Mar 2012
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    You will probably find a piston that will fit but with a two stroke you will struggle to get the valve timing right, it probably is not worth the effort but we all know that has never stopped you before.

    You can find all the piston manufacturers catalogues on line, all you can do is go through them and if that fails then cast another.

    Casting one is not as hard as it sounds but again because it is two stroke you need locating pegs for the rings which makes it a lot harder. I have never cast a 2 stroke piston but I have done 4 stroke ones very successfully for small engines.

    If you stick a bit of the petrol on a flag and let it evaporate you can tell if it there was two stroke oil in. If you are not experienced at that then stick the same amount of pure petrol next to it.

    Easiest solution is ebay for another engine.

  3. #3
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    If you can get the rings out and dress the skirt and lands and, the rings haven't worn unevenly or lost their temper - maybe it will run again. The Ryobi's need compression to start though. I have a similar cylinder here that I did the above to and it wouldn't start but it was the very narrow ring version.
    Don't bin your strimmer though. I have a few I'm using to test engine modification and if there is an intact cylinder and piston when I'm finished you can have it - but don't hold your breath.
    I'm told the Ryobis often fail by loosening their crank pin - evidenced by it wearing through the rear crankcase plate. If you find one like that, chances are the cylinder is fine. Ask around at the garden centres for machines they have taken in for repair but abandoned the idea due to parts (and crucially, labour) costs. I think a piston kit can be bought for the Ryobi though - at what cost I do not know. Obviously only viable if the cylinder isn't chewed up.

  4. #4
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    Iíve scraped the cylinder wall nice and flat and, if I find my cylinder hone, I intend to hone upper part of cylinder lightly. Canít hone lower part as cylinder there does not form a complete circle so intend to hone that part by finger holding a single hone.
    Managed to get bottom ring out in one piece. Size is 36.5 x 1.5 x 1.5 mm. Looks like piston will clean up. Now struggling getting top ring out. Intend to clean up the rings on the lathe if I can clamp them at right diameter. Brain working in top gear for a solution.
    Drives a Smart Cdi - 65 to 85 MPG

  5. #5
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    Quote Originally Posted by tolsen View Post
    Looks like piston will clean up. Now struggling getting top ring out.
    That's the difficult part. Getting it out without it bending out of round or breaking. If the former, than the temper from the ring has been lost.

    Quote Originally Posted by tolsen View Post
    Intend to clean up the rings on the lathe if I can clamp them at right diameter. Brain working in top gear for a solution.
    New rings would be better by far - if available. With dimensions, possibly for another engine eg Zenoah - parts for which are easier obtained. (I have three Zenoahs here and somewhere I have I think documented the bore sizes - I'll see if I can find the sizes later).
    If there's a 36.5mm bore version, then rings should be available. The Zenoah is used in model boats and there's a thriving market for parts.

  6. #6
    Join Date
    Sep 2011
    Location
    Cornwall
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    109
    A good deed like loaning your tools or equipment to a friend, neighbour or almost anyone really usually works out fine in most cases but on occasions such as this maybe one should consider not to ever again.!!!
    Also in some cases the said loaned tool's or equipment never ever gets returned, or they may have had it so long you simply forget who the hell you loaned it too in the first place. Speaking from experience the worse culprits are relatives.!!!

  7. #7
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  8. #8
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    Thanks for your good advice guys.

    I managed to get the top ring out too. Cleaned the ring grooves. Cleaned piston and cylinder down to the flat surface so only removing ridges. The grooves will retain oil hence advanced lubrication.

    Slid the rings onto a pipe separated by a few wraps of electro tape. Cleaned up rings using a file and fine emery cloth. Then reassembled and engine started on the first pull.

    Last edited by tolsen; 04-08-2018 at 09:57 AM.
    Drives a Smart Cdi - 65 to 85 MPG

  9. #9
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    Result!
    No rings available for PLT 2543 it seems.

  10. #10
    Join Date
    Jan 2011
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    uk
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    Quote Originally Posted by pinger View Post
    Result!
    No rings available for PLT 2543 it seems.
    You can get a long block for it (£85)
    https://www.magic-parts.co.uk/cgi-bi...&ACTION=Search

    Or you could buy a 2nd hand one for £22, which should a slightly better piston than the OPís

    https://www.ebay.co.uk/itm/Ryobi-PLT...03f7%7Ciid%3A1

    PS: you CAN get new rings
    https://www.ebay.co.uk/itm/Piston-Ri...-/172342306402
    Last edited by reinaldo_is_spam; 04-08-2018 at 10:43 AM.
    You're so money supermarket and you don't even know it!

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