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Post by bare on May 5, 2010 20:38:32 GMT 1
for my 1ua engine.
Bore is at 64.50mm
But likely close is 'good enough' for the expanders.
Primary requirement is that they be new/useable.
thanks
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Post by bare on May 7, 2010 3:08:41 GMT 1
No one? has a pair just lying about?
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Post by Norbo on May 8, 2010 16:53:18 GMT 1
You dont realy need them, mate its not something i would worry about
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Post by dredge3 on May 8, 2010 23:03:05 GMT 1
They arnt listed in the LC but are in YPVS..dont know why. My YPVS hasnt got them in. Its only for the scraping ring....I think
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Post by bare on May 13, 2010 4:10:58 GMT 1
Yesss I really DO need them. My bores are at .0035" clearance (bungling reborer).
Soo.. Pro X pistons.. Rock (rattle badly) at each change of direction when they are Missing their expanders. OEM pistons are of a different taper and don't suffer this problem as much.
The expanders serve to centralise the pistons in the bores and act as shock absorbers to prevent the rocking action against the bore sides.
Now.. you know WHY so many engines rattle like rocks in a beer can
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Post by dredge3 on May 13, 2010 13:48:16 GMT 1
"you know WHY so many engines rattle like rocks in a beer can" Cos they had a bad rebore  |
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Post by bare on May 15, 2010 4:17:17 GMT 1
No arguement... But be aware that ANYTHING over .002" clearance is Bad news .. and doubly bad if not using OEM pistons. Which by any one's yardstick are a superior choice/product.
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Post by dredge3 on May 15, 2010 11:07:30 GMT 1
Dont Yam only list up to .50 over std pistons?
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Post by bare on May 24, 2010 17:47:00 GMT 1
Certainly do
Although I have what looks to be OEM pistons with 'ART" cast in the inside skirt in a marked 0.75mm oversize. Old ? as in yama cut back on supplying oversizes at some point ?
Got my engine back together today, with the expanders and I refitted the RIK rings. Finding a much tighter rend end gap with the RIK's than with the brand new oem Yama ones.
Short story: Piston rocking noise is 90% GONE.
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