Ryobi plt2543

[RCD_70]

New here, well yesterday anyway. I have a Ryobi PLT2543 Strimmer, refuses to start. So far I have done a compression test 90psi after 3 pulls so guessing that's pretty good? Ordered and installed a carb rebuild kit,and new plug,fuel lines and pick up filter and pipes. Still wouldn't start. So being as I'd changed all that and have good compression, good spark, but overfuelling so I ordered a replacement carb. It arrived today couldn't wait to put it on and fire it up...but nothing. Plug is very wet, spark is good. I've disconnected the kill switch so spark is permanent to rule that out but still nothing. So if I've got great spark, fuel & compression what could possibly be causing it not to even get or sound close to firing? I've never had a 2 stroke behave this way from, motorbikes, dad's old petrol garden tools, my chainsaws etc. Driving me nuts 
All help appreciated
Rich..

[Mick]

Hi Rich, and welcome to TGMF.

I would probably nip the fuel line or pull it off the carb and try and start it, just to make sure it's not still flooded. If it starts to fire after several pulls that will at least tell you that's the case.

It's also possible the flywheel key is sheared and putting the ignition timing way out, but that is quite a lot of work to strip out just to check it.

[RCD_70]

Hi Rich, and welcome to TGMF.

I would probably nip the fuel line or pull it off the carb and try and start it, just to make sure it's not still flooded. If it starts to fire after several pulls that will at least tell you that's the case.

It's also possible the flywheel key is sheared and putting the ignition timing way out, but that is quite a lot of work to strip out just to check it.

Hi Rich, and welcome to TGMF.

I would probably nip the fuel line or pull it off the carb and try and start it, just to make sure it's not still flooded. If it starts to fire after several pulls that will at least tell you that's the case.

It's also possible the flywheel key is sheared and putting the ignition timing way out, but that is quite a lot of work to strip out just to check it.

Thanks Mick, never thought of that being a possibility. Also read a thread on here yesterday about a similar problem but a different manufacturer. And problems with the exhaust port.will persevere later.
Thanks

[RCD_70]

So today I bit the bullet and stripped engine out, after trying to clean up the exhaust port, checked the fly wheel was still in position. So there are some marks (pretty deep) on piston but the compression test I did yesterday as over 90 psi on three pulls. Bottom of engine was full of stale and old fuel, found one bit of what looked like the thread from spark plug hole. It can only be the piston and / or ring, but why would the compression test reading be so good..completely baffled by this one, attached are pictures of piston with the scoring on inlet side, and there's 2 or three notches at side of piston crown. Cheers Rich..