Subject: Re: Thanks for advice on Fork Assembly Problem, TFN
Author: Martin Cooke
Date: Feb 20, 2002, 9:14 AM
Post ID: 1709683784
reading L&A Robertsons(?) post got me interested in the nicasil process,
this is what i found if anyone is interested:
"Nicasil is NOT a coating as such, it is a process whereby the
chemical constitution of the aluminium alloy itself is changed to
withstand the action of the rings scuffing against it.
It is ONLY used on the barrel, i.e. the inside of the cylinder, the
surface against which the rings scrape. It is not used on piston-
crowns nor cylinder heads, as these have no need for low-friction
surface.
Because aluminium is way too soft and far too abrasive to cope
with rings scuffing along it, the first aluminium cylinders had steel
inserts, then chromated sleeves, but the Nicasil is the modern way.
Not only Hirth, but many other manufacturers use this process,
pioneered by Mahle in Germany many years ago. Very simply,
they coat the cylinder with a Nickel-rich clay (ceramic) then bake it
at very high temperature. Finally they machine off the glazed
ceramic down to the original dimensions, where the newly re-
exposed aluminium surface is now much tougher and extremely
resistant to abrasion, known as Nicasil-treated cylinder wall.
Nicasil treated aluminium cylinders are sieze-resistant, but not
entirely sieze-proof. Even if they do suffer a severe heat seizure,
you often need to replace the rings (and often piston too) but the
cylinder is usually still perfect. Only if some of the piston rubbed
off onto the cylinder-wall, do you need to "scrape" this contaminant
aluminium deposits off the cylinder, using a cylinder-honer.
This Cylinder-honer is an expensive device, not to be confused with
the "cheaper" spring-loaded gadget fitted to a hand-drill.
The proper honer will remove aluminium deposits without damaging
the Nicasil surface. The cheaper device, springloaded, three-
legged abrasive-pads, is used mostly to remove "glazing" from the
cylinder, a contaminant from burning gasoline and oil, which
undergoes high-temperature polymerisation and caramelisation.
Yes, gasoline constituents could break down into various sugars
(curcular hydro-carbon chains), which could then form caramel of
sorts. This is that brown goo often found on the exhaust (hot) side
of the piston.
Glazing is usually invisible but can be identified by the way it
reflects light.
Excessive use of an anti-glazing cylinder-honer will eventually
remove your Nicasil layer, leading to constant seizures of the rings
against the exposed aluminium ally.
If your barrel really needs a good honing after a severe seizure,
rather take it into a decent 2-stroke workshop for a proper job."
_____________________________________________________
Keith Pickersgill
Xplorer UltraFlight, Performance Paramotors
Cape Town, South Africa.
Tel: +27(0)21 555-1752
Fax: +27(0)21 555-1753
Mobile 082-414-8448
email: in-@x...
http://www.xplorer.co.zaWorld's best paramotors
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----- Original Message -----
From: "L&A Robertson" <lymana-@earthlink.net>
To: <Loopfram-@topica.com>
Sent: Wednesday, February 20, 2002 4:42 PM
Subject: Re: Thanks for advice on Fork Assembly Problem, TFN
| ------------------------------------------------------------ Two Great Bonus Offers From Palace of Chance casino Get $50 Free with a $50 Purchase - Use Coupon: EB74R and up to $200 in Match Play - Use Coupon: Q637Y http://click.topica.com/caaahsGb1dfltb2DS92a/Palace ------------------------------------------------------------ Nickasil is nickel chrome blend the nickel is the common bond material between chrome and aluminum I cked from a German BMW site as they were the first to use it the combination favors nickel ----- Original Message ----- From: "Martin Cooke" <cook-@virgin.net> To: <Loopfram-@topica.com> Sent: Wednesday, February 20, 2002 1:34 AM Subject: Re: Thanks for advice on Fork Assembly Problem, TFN
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