From: Pete Fisher on
The garage clear out continues apace and long forgotten items have
resurfaced from beneath the work bench.

An original 1979 SWM 250 MX silencer. If I can loosen the re-packing
screws I reckon that is definitely worth a 99p listing on Ebay.

A Gilera Nordwest standard piston which IIRC came along with the
Nordwest engined Saturno when I bought it. Used, but looks in remarkably
good nick. I was just about to sling it in the 'metal' box for taking to
the tip when I did an Ebay search for used piston. A surprising number
listed, mainly for SO brit stuff.

I doubt there is any problem sourcing a new Nordwest piston from Uncle
Bob Wright, but it seems SO Gileras are falling in to the hands of the
type that may want to save a pound or two after having a blow up (Simon
excluded naturally), but would anyone on here buy a used piston? I've
certainly bought used matching barrel and pistons in the past (always
had a spare ready when racing the Rotarini). I suppose for absolute
unobtainium it might be the only option other than having one made.


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| Pete Fisher at Home: Peter(a)ps-fisher.demon.co.uk |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+
From: Grimly Curmudgeon on
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Pete Fisher
<Peter(a)ps-fisher.demon.co.uk> saying something like:

>I doubt there is any problem sourcing a new Nordwest piston from Uncle
>Bob Wright, but it seems SO Gileras are falling in to the hands of the
>type that may want to save a pound or two after having a blow up (Simon
>excluded naturally), but would anyone on here buy a used piston?

If it was exactly the size I needed and in good nick, yes.
From: Pete Fisher on
In communiqu� <ejtg36t5vr7m6rg36cvg5k905894fnm5il(a)4ax.com>, Grimly
Curmudgeon <grimly4REMOVE(a)REMOVEgmail.com> cast forth these pearls of
wisdom
>We were somewhere around Barstow, on the edge of the desert, when the
>drugs began to take hold. I remember Pete Fisher
><Peter(a)ps-fisher.demon.co.uk> saying something like:
>
>>I doubt there is any problem sourcing a new Nordwest piston from Uncle
>>Bob Wright, but it seems SO Gileras are falling in to the hands of the
>>type that may want to save a pound or two after having a blow up (Simon
>>excluded naturally), but would anyone on here buy a used piston?
>
>If it was exactly the size I needed and in good nick, yes.

Good point. The bialbero motor features a nikasil bore (so no oversize
pistons without a 'big bore' conversion barrel) but three 'classes' of
piston for piston/cylinder matching. I certainly don't have anything
capable of measuring accurately if it's 'A': 97.964 - 97.970 or 'C' :
97.976 - 97.982.

If ICBA I might call in to Piston Services[1] if they are still in
business and get them to mic it up.


[1] An excellent place for rebores. The owner used to have an AJS *car*.

--
+-------------------------------------------------------------------+
| Pete Fisher at Home: Peter(a)ps-fisher.demon.co.uk |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+
From: Andy Bonwick on
On Sat, 10 Jul 2010 15:15:44 +0100, Pete Fisher
<Peter(a)ps-fisher.demon.co.uk> wrote:

snip>

>Good point. The bialbero motor features a nikasil bore (so no oversize
>pistons without a 'big bore' conversion barrel) but three 'classes' of
>piston for piston/cylinder matching. I certainly don't have anything
>capable of measuring accurately if it's 'A': 97.964 - 97.970 or 'C' :
>97.976 - 97.982.
>
You won't get an accurate measurement in your garage when you're
looking at those sort of limits, you'd have to make sure the
micrometer and piston were left together in a room held at 18c for
about 12 hours. A sigma comparator is the best way to check that sort
of thing but they're not that common in rebore shops.

From: Pete Fisher on
In communiqu� <ir6h36dlbsghpf40jpas12s9fho8fcegjb(a)4ax.com>, Andy Bonwick
<nospam(a)bonwick.me.uk> cast forth these pearls of wisdom
>On Sat, 10 Jul 2010 15:15:44 +0100, Pete Fisher
><Peter(a)ps-fisher.demon.co.uk> wrote:
>
>snip>
>
>>Good point. The bialbero motor features a nikasil bore (so no oversize
>>pistons without a 'big bore' conversion barrel) but three 'classes' of
>>piston for piston/cylinder matching. I certainly don't have anything
>>capable of measuring accurately if it's 'A': 97.964 - 97.970 or 'C' :
>>97.976 - 97.982.
>>
>You won't get an accurate measurement in your garage when you're
>looking at those sort of limits, you'd have to make sure the
>micrometer and piston were left together in a room held at 18c for
>about 12 hours. A sigma comparator is the best way to check that sort
>of thing but they're not that common in rebore shops.
>

ISWYM. Possibly explains why the pistons on Ebay are from machines of
the + tens of thous oversize era.

Tip it is then

--
+-------------------------------------------------------------------+
| Pete Fisher at Home: Peter(a)ps-fisher.demon.co.uk |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+