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Post by parrott500 on Jan 13, 2020 18:29:45 GMT 1
Hi has anyone rebored YPVS cylinders to 2.5mm? before I have them bored have you had issues with using standard head gasket or powervalves making contact with piston? or will I need any special parts?
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Post by midlifecrisisrd on Jan 13, 2020 19:08:19 GMT 1
From what I've heard 2mm on 31k's and 2.5mm on 1ua's is absolute max
Anything 1.75 and over would need the pv clearance checked
You will need to open up the head gasket too
Some have had issues on 2mm with the liner being too thin in places causing seizing or uneven piston wear due to hot spots
I'm sure some of the liners are not exactly square in the bore as despite machine shops boring exactly square to the cylinder base it is slightly off centre at the top
Steve
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Post by Tobyjugs on Jan 13, 2020 19:21:40 GMT 1
I've got quite a few worn out Ypvs barrels at 2.5 mm+ all old race spares
Don't know what type they are.
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Post by parrott500 on Jan 14, 2020 10:28:28 GMT 1
I have spoken to Grampian motors about boring the cylinders and they said they would modify powervalves to suit bore size at no extra charge if needed and they say standard head gasket should be ok upto 2.5mm so i will see check that out when I put it together.
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Post by yamman1066 on Jan 14, 2020 17:22:23 GMT 1
hi,i will not go over 1.75 on YPVS cylinders
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Post by midlifecrisisrd on Jan 14, 2020 17:34:58 GMT 1
In same as above
Sent a set to Grampian on 1.25 and they came back on 1.75
They were for an expensive hybrid build so I wasn't comfortable using them so stuck them on ebay for £200 with the new pistons
Couldn't really complain as the whole engine only cost £100 so nothing lost
2mm oversize is what you do to sell it when it keeps blowing up 🤣
Steve
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Post by parrott500 on Jan 14, 2020 21:57:43 GMT 1
Thanks for views i will have a good think before i do anything else.
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Post by chrisg on Jan 14, 2020 22:46:11 GMT 1
PJME do re sleeving if you want to get back to std.
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