Topic: Help please on cylinder base o rings

[Colin Tweedie]

I have had problems with oil leaking from the cylinder base and have blamed the base gasket , on close inspection the grooves for the o rings around the base of the barrels measure 2mm wide by 3mm deep the o rings I removed have a 2mm section . It seems obvious that these rings will not seal ? Parts book say they should be 61.78 x 2 ? Are these early or late barrels that require a square section ring if so anybody know where I can get the proper seals .A all the gasket sets I have only have the 61.78 x 2 rings included

[MCRider]

Its not likely that is your problem. Those ORings keep oil from wicking up between the steel sleeves and the aluminum block. On large displacement engines, those are often machined away and no ORing is used at all, with no adverse effects.

IMO Any ORing that fits will serve that purpose. If none is used you likely would never know.

[turboguzzi]

dont use them either on my 500/4, no problems.... look at where they seal, they have little to do with leakage from the base gasket

[dave500]

ive omitted them on 500s before aswell,no worries.

[fang]

+1 I've built three 900cc motors, none have O-rings, and none leak at base gasket.