I am redoing the top end of my 1961 ES2. The question I have concerns the .090 Diameter hole the is drilled on a angle into the base of the cylinder. Is this the so called cylinder oil passage? Mine appears to be a blind hole with no outlet into the cylinder. Is this correct for the 1961 ES2 or should there be an outlet into the cylinder and if so what is the correct diameter of the outlet.
Thanks in advance,
The hole at the back of the cylinder meets a hole in the crank case joint surface. That turns various internal corners from intersecting drillings which come from the oil pump. You won't see daylight if you look down it. All the singles had them. On some (Inters) the supply can be adjusted, but they were designed to be liberally oiled (inside and outside).
Ok, but mine does not have an outlet hole to the cylinder wall. Is not having an opening in the cylinder wall correct for a 1961 ES2? If not I will put one in, is it drilled straight thru at the .090 diameter?
Sorry can't help. Some have said it's not realky needed with modern oils. Has the bike already run for years without it, and without scuffing the cylinder wall? Does oil even come up from the hole when the engine is turned?
Oil does come up when the engine turns. The reason for the top end build is I was renewing the base gasket and found the piston badly scored on the rear with no damage to the cylinder. The engine does run but hasn't been run for years before this summer. I have read mixed information on this subject with Norton singles and just wanted to get to what I need done. I'm thinking I will drill it through the cylinder wall anyways since the piston was badly scored.
The hole through the rear cylinder wall was dispensed with for post-war side valve engines but should still be there for OHV Singles.
Perhaps your ES2 cylinder has been relined and not drilled through ?
Peter's undrilled liner suggestion seems likely. With the scoring to the rear of the piston I don't think there is anything to lose by drilling on through. The photo shows the oil feed on a '57 (ish) 19S cylinder. The drill in the pic is 2.4mm.
Thanks, I will put the hole in the cylinder.
It does not appear to be relined, but I'm not sure totally. What ever it is it is bored .020 over an was out of round slightly at the bottom of the cylinder. I bored it to match the rest of the cylinder at .003 over piston size.
Thanks everyone for your input.
I put the hole in successfully, but before I started to drill I wanted to check what I was up against.
I borrowed a tiny scope from a locksmith and took a peek inside at the bottom of the hole and found that it was indeed a blind hole. It was never drilled through the cylinder wall, which made drilling easier.
Thanks again for all your help. There is not much information on the ES2 here in the USA.