860 piston rings

john stringer · Post by **john stringer** » Sun May 30, 2010 4:35 pm

Last x-mas i treated myself to a disassembled 860GT. I am in the process of rebuilding the engine, about to install rings and piston onto the rear cylinder. Can anybody advise which of the two compression ring goes into the top groove. one ring is stepped and the other wedge shaped (keystone). Bores are good ring gap is less than 0.020thou so I want to build it up as it is and fettle out any faults then go for a full restore later.

John (ex-Rhodie)

BEVEL DAVE · Post by **BEVEL DAVE** » Mon May 31, 2010 6:07 am

Stepped in the top usually.

wdietz186 · Post by **wdietz186** » Mon May 31, 2010 10:13 am

Look carefully at the rings near the ends usually there are etched markings often TOP or UP .Most often the top ring has a chrome facing and is shinier than the second ring which often has a black oxide coating.

john stringer · Post by **john stringer** » Mon May 31, 2010 1:16 pm

Thanks guys. I have the Ducati shop manual, also the Haynes but neither make any ref. I believe it was in one of Mick walker's books that there was a more detailed illustration but I'll go with your guidance.
Thanks.
As this is my first Duke are there any other tips?? I am paying very close attention to shimming on everything.

jockduck · Post by **jockduck** » Wed Jun 09, 2010 4:17 am

No real problems rebuilding a bevel twin, I did my first one with a Haynes manual and that worked out OK, just take your time and check everthing, previous owners are usually the biggest problem particularly with wiring. There are some horrible suggesions out there for getting around special tools usually involving hammers, making a copy of a genuine tool is not difficult but saves damage now and in the future.
Jock