Race Engine Forum UK

Hi Guy,

I need to de-glaze the nicasil bores of an engine I am currently building in order to fit new pistons and rings and wondered if I need to use any particular grade/material of flex hone (or similar)?

Thanks

Martin

I don't know enough about this to comment substantively, sorry.

My guess is that the coating - if honed - will be removed completely and the matching of rings to coating is very critical.
The only people I know of in the UK who might be able to advise constructively on the overhaul might be Poeton Coatings , but they may well say the liners need to be rebored and recoated - and no doubt will want to know about your rings and their suitability for the new coating - which may well not be Nicasil, I don't think they use it.

http://www.poeton.co.uk

GC

Thanks Guy,

The new rings are to suit the nicasil bores so shouldn't be a problem.

I will see what I can find out and post it here.

Martin

Nickle Silicone Carbide coating can be honed but because it is extremely hard requires diamond matrix hone stones to machine hone. This is if applied on steel. On aluminum I would NOT hone at all. The bore must be free of ridges or steps ETC for machine honing. I would recomend hand deglazing only in any case.

This process is used on most air cooled aircraft engine cylinders in stead of nitriding and under those circumstances I only hand deglaze to speed ring seating but it is not required. This also opend porosity previosly covered by varnish from running and helps carry and hold oil during break-in. This would be more critical on aircraft due to severity of service and not so on water cooled in my opinion.

For hand deglazing, green Scotch Brite seems to leave a nice finish. I have also had good results with gray. Again, very light and even and, with some light oil or solvent then follow a proper cleaning regime to remove all residue.

HTH
Robert

Guy,

I have found that Flex Hones are available for nikasil bores, they are aluminium oxide instead of the normal silicon carbide. I have ordered one and am waiting for it to arrive, I will post results.

Regards

Martin

I use the Flex one . A few seconds on the coating is enough to bust the glaze . This nikasil stuff is TOUGH. Use a bore guage to check the result after if you're worried. The bikes I work on all have nikasil barrells. It rarely goes wrong.

Chris

Edited by GC