Ryobi post mortem!

John Rumm · 2010-04-20T12:01:36+00:00

A follow up to my non starting Ryobi trimmer thread a few weeks back.Recap: line trimmer driving a hedge cutter attachment - started and ran fine for perhaps 20 mins or so before cutting out, and then would not restart - even when cold. The usual diagnostics seemed to show that fuel was getting into the cylinder, there was a spark, and air but no joy.Anyway, I dropped it off at a local garden centre service place for investigation. Just got a call to say its beyond economic repair since the cylinder is scored and hence its not drawing the fuel mixture in properly on each stroke. They said it looks like it had been run without two stroke oil in it.Just wondering what could have happened here. Its only about a year and a bit old, and has had a total of a can and a three quarters of fuel through it in its life. Fuel was mixed with the right ratio of oil[1], according to the instructions with the oil - the complete container of oil to 5L of petrol. The petrol was super unleaded, and the trimmer spec says it required 95 RON or higher. So what could have gone wrong?I presume the damage was done on its final run (the first of this season) - since it started easily and ran fine for a while. I was using up the remaining fuel in its tank which was about 3/4 full - that had probably sat in its tank since last autumn.So does the two stroke oil degrade in some way? Was the higher than required octane a problem? or does this sound like problem related to product quality?The oil in question was Stihl oil like this:

Ryobi post mortem!

Apr 20, 2010 43 Replies

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John Rumm 16 years ago

Well I finally got the clutch off and was able to separate piston from cylinder.

From what I have seen, the foreign object scenario looks most likely. See what you think - modified story here:

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andrew 16 years ago

Looks like two incidents, the score on the intake side has been polished but the ones that took out the piston look fresher. Are you sure there is nothing missing from the carb or air cleaner?

AJH

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John Rumm 16 years ago

Yup - I might check see if those prices are right...

(I suppose I ought to take the carb apart and see if I still have the same number of bits as shown in the diagram!)

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John Rumm 16 years ago

Not having seen the inside of the carb prior to this dismantling its hard to tell. The air filter is just a bit of foam rubber the pushes into a recess - no frame or cages as such. I might take it apart and see if it matches the parts diagram.

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