Sparky Posted May 11, 2018 Share Posted May 11, 2018 Hi all, had the engine on my Ros125 have a bit of a meltdown, is it possible to get this rebored, looks like only top end damage, the original sysmptim after it cut out mid flight was it had no spark, replaced coil and plug and then had good spark, could the coil breaking down of caused a weak mix to cause this? thanks in advance Quote Link to comment Share on other sites More sharing options...
James Troup Posted May 11, 2018 Share Posted May 11, 2018 (edited) It might be more due to mixture? I've no experience with this particular type of engine so I can't help you in that respect. How bad is the scoring though? Can you feel it with you're finger nail? It might be OK once you've got the mixture dialled-in/checked. Cheers, Edited May 11, 2018 by James Troup Quote Link to comment Share on other sites More sharing options...
Sparky Posted May 11, 2018 Author Share Posted May 11, 2018 Hi, yes you can feel the scores unfortunately Quote Link to comment Share on other sites More sharing options...
Hann__ Posted May 11, 2018 Share Posted May 11, 2018 What`s the cylinder like? Is the cylinder on those engines Nikasil plated? If so no rebore options. If the aluminum from the piston has only melted onto the cylinder without damage you might get way with removing the galling with mutiatic acid and fitting a new piston - after finding out why it seized in the first place.. 1 Quote Link to comment Share on other sites More sharing options...
Sparky Posted May 11, 2018 Author Share Posted May 11, 2018 Thanks, i just checked the spec for the newer 125 light engine which lists that coating but this is an older engine I think, are there any ways of telling by looking at the bore Quote Link to comment Share on other sites More sharing options...
Neilzy Posted May 11, 2018 Share Posted May 11, 2018 They all have Nikisal Coatibg even the older type there not a rebore option sadly. New piston & barrel is the only way. Quote Link to comment Share on other sites More sharing options...
GR002 Posted May 11, 2018 Share Posted May 11, 2018 I had a Ros 125 engine and had same problem. I googled and found a company that refurbished the cylinder ,they built up the scratches rebored and recoated it. this cost me £150 and I bought a new piston. This was years ago and can not remember the company but there were a few. I had one of the first Ros engines in the country from Noel Humphries. They were good engines but once it started to have faults it was never ending so changed to a Moster. Quote Link to comment Share on other sites More sharing options...
Sparky Posted May 11, 2018 Author Share Posted May 11, 2018 Many thanks, Quote Link to comment Share on other sites More sharing options...
notch Posted May 19, 2018 Share Posted May 19, 2018 (edited) Can get the cylinder re-plated - done it a few times, good results. Check your carb - probably needs to be refurbished with new parts. Replace the internal filter & check the jetting. Also check for air leaks in the crankcase. Edited May 19, 2018 by notch Quote Link to comment Share on other sites More sharing options...
Sparky Posted May 19, 2018 Author Share Posted May 19, 2018 Many thanks, what sort of cost is the re-plating?Many thanks, Quote Link to comment Share on other sites More sharing options...
notch Posted May 20, 2018 Share Posted May 20, 2018 Used the US branch of these guys: http://www.langcourt.com/page29.html before. Give them a call for quote. 1 Quote Link to comment Share on other sites More sharing options...
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