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Dommie barrel re-sleeving


Has anyone had first-hand experience of re-sleeving back to original bore? I have seen doubts raised about the strength of the barrels after being bored out to take the sleeves.  I only want to get it to touring trim, not racing. Mine is a 99 with +040" rebore and new pistons, but I can now afford to get back to original. (A little inheritance money) The existing has one cracked spigot at the top so I would either have to chance it and leave it there (the other one is OK) or have them machined flush.  This would then leave unfilled recesses in the head and I'm not too confident about the stability of the rings you can get to fill them.  I would appreciate responses only from people who have first-hand experience of this work on their bikes.


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Thanks Charles but what, if any, disadvantages were/are there?  Thinner barrel material for instance can weaken the barrels.  What engine was it and roughly how many miles have you done since?


Results can vary.I have seen sleeves visible through holes in the bottom of the barrels. Its possible that 88 barrels have more meat and give a better result?.Is it a possibility to sleeve +40  99 barrels  down to 88 size and finish up with a strong barrel  and an undersize 99??.

A 1959 99. the barrels were standard but had been chrome plated at some time and were horribly rust pitted.  The engine was aquired dismantled and incomplete . Tim Payne restores all types of exotic stuff including vintage F1 engines as well as one off modern stuff. No problems experienced or expected. Choose a reconditioner who understands old engines and you should be OK.


Hi, Lionel.

I had my 650SS re-sleeved back in 2015. It was 0.060" oversize and I had it sleeved back to standard. Apart from the pistons supplied then being too heavy and causing too much vibration, which I reported on in Roadholder, it was fine and a new set of lighter pistons sorted things. Only done about 1,500 miles since (I know, it should be more!) but no problems so far and the oil burning has stopped. I had new valves and guides and seats recut at the same time and total cost, including original pistons, was some £650, so you will need your inheritance! As many report, of course I don't ride as hard now as once upon a time, so the engine should have an easier time. Don't know where in the country you are but I had the work done through Lee Brothers of Sowerby Bridge in West Yorkshire.


Many thanks everyone.  I just needed someone with actual experience of having it done - not opinions as anything can be rated "A load of poo" or "The best thing since sliced bread" unless you've had it first hand.

My next question is - what should I do with the split spigot ring at the top of one of the barrels? It was this problem which started me thinking about re-sleeving.


My 88 was resleeved by PO. Never crossed my mind to worry about it. Possibly the outside diameter of the barrel is same as the larger engines so maybe wall thickness is more, but has anyone measured them? I thought RGM list liners that have spigots on top? That looks ideal to me. Maybe worth talking to them (and giving them the business?)


The spigots on my 650SS at + 0.040" cracked, so I had them machined off. I ordered the rings to go into the recess in the head from Norvil. They were a joke. Too deep and too narrow. There was no way they were going to fit, and Norvil's advice to have them machined to fit would have lead to them shattering. They must have thought I had a point, as they refunded me. 

I used the gasket for a spigotted barrel, as I did not like the idea of the non-spigotted gasket poking out into the combustion chamber. The idea is that the recess will fill with carbon in time.

It is a stop-gap though, and next on the agenda is to have the barrels re-sleeved, as others here have done, as well as a head refurb, as Lance did.

As he mentioned, it is important to get the correct weight of pistons, or you will need a full engine strip & crank re-balance.



It might be of assistance to know that Norton used Volkswagen Beetle pistons in Commandos. I had a leaf through the old catalogue a few years ago, and found at least 14 different diameters of repair pistons and a selection of sleeves. Its worth trying an old Hepolite catalogue.

Many thanks for that. I have other work I need RGM to do so I'll have to have a word with Roger.  The sleeves do look and sound ideal.  The bike is never going to get a hard life anyway - less than 1000 miles a year I expect! 


Many thanks for the input chaps. At present the barrels have been rebored to +.040" and I have "new" standard compression pistons (bought about 10 years ago from Andover-Norton for around £95!).  Piston prices have more than doubled but at the same time I can sell mine to offset that.  Only a part of one top spigot is cracked - about 1/4 of its circumference - and I had been considering leaving it that way when I put the bike back together, but I suppose it could break off unless it was possible to of weld or braze it. I might take it up to Norman White and get his professional opinion.  Incidentally I know he has had Norton cast-iron barrels blasted and stove-enamelled as a finish.  I saw one years ago at my local blasting shop in Southampton with his name on it! (Trestan, only a mile or so from where I live and who did my frame, cycle parts and head.)


The 60+ spigot on my old 99 cracked about 25 years ago. So I got out a hacksaw and removed it plus the other side to balance things up. Originally I fitted one of those plain Hallite gaskets. This was a little thinner than the the standard copper composite version but my reasoning was that this would help to make up any fall of compression due to the loss of the spigots. Whether it actually did I am not sure. The bike ran perfectly well, including at regular 'track' days for the next 15 years and when I ran out of Hallite gaskets I went back to the standard type. 

By 1965 all of the big Norton twins had lost their spigots and not suffered any cylinder head problems. The only times that I have had issue with removed spigots was due to stuffing 10.5 compression pistons inside the barrel and fitting a solid copper gasket. Then I got oil leaks galore. A problem only solved after 3 attempts by changing the head gasket back to a composite version.


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