Looking about minisport, I see that there are 1098 standard bore pistons available, http://minisport.com.au/prod26.htm but no 998 standard pistons

The bores are the same, so is there a difference in the pistons skirt, or gudgeon attachment, or are they actually the same thing?

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998 pistons are tall

1098 pistons are short

ie: 998 crank is short stroke so therefore tall piston

1098 cranks are long stroke so therfor short piston

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

So are 998s available new in standard sizes?

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Ahhh,,, hang on a min & i`ll check



i`ll just get my glasses on




won`t be a sec







Karcraft list them as part number (998 STD) set of 4 pistons inc rings

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

That's funny, because the website doesn't list 'em.

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AE Hepolite P/N 20773 STD

Karcraft P/N 998 STD

http://www.karcraft.com.au/catalogue/pa ... 0&part=998

Why do you want std pistons? Most blocks these days have worn bores and require boring & oversize pistons. Fitting std pistons to a std bore that has been honed will most likly give you to much piston to bore clearence and you will end up with a smoky, oil burning "reco" motor. I suggest you purchase 020 oversize pistons and do the job properly.

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Have a Nice Day.
If already having a nice day please disregard.

Maybe it's not for a 998 block

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Hotted up 850??? Excellent

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Have a Nice Day.
If already having a nice day please disregard.

I know where you're coming from, and I'm probably just spliting hairs, (and I know that cush has already come back and advised that they are not for a 998)... but you don't always need to over bore the block... your better off getting the motor apart and seeing what it actually needs..

I have one of those funny late GT blocks that are basicaly a small journal 11 stud, thick flange 1100S blocks... know the one anyway, it was a total virgin, standard bore size. I pulled it down and it turned out that it just needed a hone,, not bad for a 30 something year old donk hey the piston to bore clearance ended up 0.0035", so next time round it will probably need over boring (0.004 is the max clearance recomended,, by the factory anyway)...

Or, you could just overbore it anyway and keep it down to 0.0025 at the min clearance (provided it isn't going to revving its guts out its whole life )

But yeah,, I reckon check it out and see what it needs... these engines aren't being made anymore so why put one that much closer to the scrap heap... or, put yourself closer to needing sleeves which are more expensive than just a bore or hone.

It's not just a piston clearance issue, but more one of bore wear.
By the time it has .001" more clearance well down the bores, it's worn oval and tapered more up the top where the rings change direction. Even if you hone it out, it's not good for compression and oil sealing.
A series donks wear their bores more than you think- by the time the rings are worn out, they really need a rebore and bigger slugs.
I would NEVER put standard pistons into an old std bore motor. It's not as though you are really extending the block's life. There are heaps of common oversizes available now, whether it's a smallbore or a 1275.
eg 1275-
+.020, .040, .060, 72.5mm, 73.0mm, 73.5mm, 74.0mm.

That's 7 friggin rebores mate.. then, you can sleeve it!

<edit> or see me for a std bore block and start again.

Smallbores (998) nearly as good-
+.020, .040, .060, .080, .100, .120.

(1098) +.020, .040, .060, .080, .100, .134" (Imp 68mm)

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I have a set of standard NOS 998 pistons for sale at half price if anyone wants them.

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

What does a re bore cost anyways?

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one van, one mini s, one knitted cardigan

$100-$150. You get what you pay for.
I have a 1098 block here a member got done a few years ago with the $100 job and the pistons are too loose... needs another rebore & pistons after about 5000 miles.
It had ring gaps of about .025" with new rings...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

i may be wrong here, (i often am) but i think cush is looking at doing a "square-ish" bore from an old 850 block like the one Deano (74snail) was talking about in another thread

so,,, if i`m right,,, then all this talk (typing) of re-bores & bore wear & why go bigger if it don`t need it etc etc etc,,, probably means nothing to Cush

??? yeah???

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.