TOPIC: Small barrel engines-rings

FWIW
The norton twins have 2series of cylinder barrels, small bolt pattern 500-600-650 and large bolt pattern.750 and 850
FWIW-2
The norton twin heads have 3 series. small 500-600-650, medium-750 and large-850
FWIW-3
Found it interesting that of my 6 small barrel NHT engines, two that I dismantled so far, had 1/8"(.125") wide oil rings. They are a bit sloppy sitting in a groove that is for a 6mm (.236") oil ring. I even conversed with a Hastings ring tech guy and he said that I was looking for something that did not exist....6mm oil rings. I researched on THEIR web sites resources and found/made up a ring pack for the 88 engine from individual part numbers rather than a complete packaged set. Their packaged sets had the 1/8 oil ring for a lawn mower or some such thing.

The ring pack I got from Total Seal to fit my 650 Manxman did not have suitable sized rings as "stock" from Total Seal for the Norton 650.
I had to have the shop I bought the rings from recut the oil ring groove to fit the available rings.
Just a tidbit of anecdotal information of possibly no interest to anybody.

Ron I'd guess off hand it has been so long that this was done that you are off on some aspect of this detail. Norton pistons have either shallow/early or deep/late compression rings. I suspect that what they actually did is make your compression ring grooves deeper since they probably only make the better deep rings,.
Why??? you might ask why I think this is so.....".I" had to cut your OIL RING grooves to make the oil rings fit or else they lied and did not really do the job. When you gave them to me. Your compression rings did fit, but the oil rings did not.
If in fact the TS oil rings were originally more than 6mm wide then they only did half the job to widen them and were clearly not deep enough since they jammed up solid and would not fit in the bore. I fixed it and they fit now!

You may be correct about my not remembering the actual events in 1982 (34 years ago?) But they supposedly did do something to make the then available TS rings fit the new pistons I had back then, but could the current ring set, which I bought from the same vendor ((several years after the first set I bought)) have been different than the ones from 1983??? This is a moot point as the current rings, thanks to your work, now fit the pistons that are in the Manxman!!!

I don't know which rings you may have gotten back then but if I'm correct you could still buy early or late norton rings back then and still can today since they must match the pistons and people still rebuild engines with either style of piston depending on what they have in their hand...
It very apparent that once you modify the pistons and install the TS rings you can't go back to either the early or late OEM ring pack.

Ron said:
They measured the pistons for ring size and sent me the closest size to the piston measurements that TS had in their catalog at the time (1982). The vendor(machine shop) then resized the piston ring slots to fit the rings???.

That’s my story and I’m sticking to it.
Ron


I must have events mixed up. 82 was the Bar Harbor rally, I was still in Kentucky in the Air Force. I did not even own a bike at that time. I did not even know you. Did you even own the bike then?
.
Move forward to 92 Gunstock NH rally I Knew you by then. .I had a BSA A-10 and my 72 combat.You had your manxman together and running there at the rally for about a day.....After the Rally, I remember your trouble finding pistons and the story of going with TS rings and you going to TS in Greenland NH.

At this point I can only feel confident in a few things.
They took your money.
They may have done some partial mods to the pistons, however they absolutely did not do a full job on ALL piston ring groves.
I'll leave it there.
Dave