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Thread: 2 stroke brush cutter started with regular petrol

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    Default 2 stroke brush cutter started with regular petrol

    My father is getting a bit ďforgetfulĒ and isnít coping too well with his garden.

    I had a cleanup at his place today and got out his good Stihl brush cutter. It had a full tank of fuel and was set with the choke already on - like someone had tried to start it, but hadnít used it. I tipped out the old/stale fuel and noted that it was clear - like normal petrol, not dark like 2-stroke. When I tried to start it, it was harder to turn over than I would have expected and made a squeaking noise. It wouldnít fire at all - not even a cough or splutter.

    It looks to me like someone has tried to run it on normal petrol with no oil in it. Do the symptoms sound consistent with this to the AusTech experts? Iíve never mis-fueled a two-stroke motor, so while I know itís a ďvery bad thingĒ, I donít know if this is what happens. Would it normally seize completely? I guess itís a situation where you just thow it out and buy another one.



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    Without the oil, yes, it will seize, but 'when' that happens will depend how long it was operated without the oil.

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    sounds like its fooked......

    the new stihl electric brushcutters are excellent.......
    https://www.speedtest.net/result/d/7...193b4402e8.png

    FTTN, 710m line length, bit faster now with draytek modem....

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    In my mind, most likely scenario is it had a quatity of pre-mix in its tank, which was topped up with straight petrol, and then it's been started and run/worked --- sometime during this stint, the highly diluted fuel in the tank (think something silly like 200:1 fuel/oil mix), has caused overheating of the piston/rings/barrel which would've started to bind (increasing loss of compression/power), until it either seized to a stop or stopped running due to load. Likely it is, the tank was then refilled with straight petrol again, but the engine now refuses to start due to the damage caused....

    ...the squeaking noise may be the piston/rings scraping up/down what's left of the nikasil coating on the bore, but then again if it's a newer Stihl unit (made in CN not the EU =), many of the bearing cages in the engine are made of high-temp plastic (not metal) and can distort/melt if overheated (due to lack of lubrication) ..and if it's a cranksahft bearing that's failed, the squeaking might be the flywheel contacting the ignition coil former (look for marks around periphery of flywheel).

    In any event, sounds like a pull it down, inspect, and replace damaged/worn parts as necessary, and reassemble job. Dunno what model Stihl it is, but I can imagine it being in the $100-$200 cost for part repair.

    Perhaps it's time to think like this? =)


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    Quote Originally Posted by hoe View Post
    sounds like its fooked......

    the new stihl electric brushcutters are excellent.......
    Thanks everyone for the advice - and Wotnot for the detailed answer to my question. I think Hoe summed up the situation nicely.

    It's shame, because it's one of the "professional" models - straight shaft, bicycle handles and a metal blade. It sounds like it's time I bought a decent brush cutter for myself, even if I mostly use it at Dad's place (our place has too many wallabies for the grass to ever get waist high).

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    I bought a mid range stihl electric brush cutter, abou $650.

    Battery lasts about an hour, longer than me.....

    usages.kangaroos.sound
    https://www.speedtest.net/result/d/7...193b4402e8.png

    FTTN, 710m line length, bit faster now with draytek modem....

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    Quote Originally Posted by shred View Post
    Thanks everyone for the advice - and Wotnot for the detailed answer to my question. I think Hoe summed up the situation nicely.

    It's shame, because it's one of the "professional" models - straight shaft, bicycle handles and a metal blade. It sounds like it's time I bought a decent brush cutter for myself, even if I mostly use it at Dad's place (our place has too many wallabies for the grass to ever get waist high).
    What model is it? Stihl make good gear, it's often worth repairing them ~ I use an older FS160 around the yard (2nd set of crank seals/rings but original cylinder is about done), but if mean&nasty is required the FS460 gets a start (sounds like a mx bike at idle =)....

    ...so just for example...if it's only lunched it's top-end, you can buy a cylinder kit (includes piston, rings, piston-pin & clips) and buy a small end bearing for somewhere between $60 - $140 depending what you buy, and it'd be fixed. If however the codrod bigend bearing has gone loose, you'd have to throw a new crank into it as well...another $100 with seals and carrier bearings.

    Typically you get an early telltale wrt if you'll need a crankshaft or not, when you pop the cylinder off, and remove clip&pin to get the piston off the conrod -- you immediately look for any discolouration (bluing) around the small end eye the piston pin runs in -- if there are signs of heat distress here, I replace the crankshaft/codrod assembly, presuming I can no longer trust the codrod.

    If there was any one positive thing (if you can call it that) coming from Stihl outsourcing production to plants in CN, is there is a plethora of cheap parts for the things, and the core engine design of the newer model range, are the same as the older EU made stuff...ie; the newer FS200 cylinder kit will fit my older FS160. Once upon a time, if your Tillotson carby started playing up, you'd buy a diaphragm/gasket/valve kit for it, and to the repair -- nowdays it's cheaper to buy a replacement carby, bolt it on, go.

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    I can't talk about Stihl's brush cutters but I have used their electric chainsaw on thick hardwood trees(30m), seems much easier and definitely less stressful then the bloody petrol things.
    I remember a mate complaining that he had to replace the crankshaft twice on his old Stihl. No crankshafts anymore, no problems.

    I have a Greenworks line trimmer, that cuts bushy stuff too. I have worked it hard at my bush retreat. 2 batteries 4Ah are essential. It is all about finding the right line to use.

    Anything thicker I use a short electric pole cutter with a 10" chain so I don't need to bend when I cut the main stems of the Lantana and weed tree saplings. Much more effective than a brush cutter.

    A while back I bought a petrol brush cutter that you strap on your back and has a flexible shaft, used it once, utter stress, now dusting away after I discovered the battery powered tools.

    Just a tip, don't but anything with less then 36V.
    Last edited by Uncle Fester; 21-11-21 at 05:18 PM.
    I am an arrogant, irritating RSole.

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    Quote Originally Posted by wotnot View Post
    What model is it?
    Itís an FS 130-Z, so not mega expensive, but it might be worth getting some to look at it.

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    Quote Originally Posted by shred View Post
    Itís an FS 130-Z, so not mega expensive, but it might be worth getting some to look at it.
    Looks like just over $50 for a cylinder kit ....be worth checking it out (if you can find/know a small engine mechanic that doesn't charge like a wounded bull =)

    Like I say, a lot depends on what's found during the teardown.

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    Thanks for that wotnot. It sounds like itís worth at least taking it in to get an opinion on whether we fix it or not.

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    Quote Originally Posted by shred View Post
    Thanks for that wotnot. It sounds like itís worth at least taking it in to get an opinion on whether we fix it or not.
    Being a 2 stroke its easy to pull the head and barrel off to check the bore condition.

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