Vintage Workshop
Services for Brough Superior motorcycles and their contemporaries

KTOR cylinder barrels page last update: 29-01-2005

First, I thought there must be some suitable castings available somewhere. So I did some research.

Unfortunately I could only find MFC's JTO barrels, and their specials for 1100cc Morgan JAP engines. Well they might do KTO ones in the future, but would not promise a date.
So I set to work and made a drawing of the KTO barrels, which are shorter and have a slightly finer finning.

Then I showed my drawing and a sample barrel to a number of foundries. The comments ranged from "Can't do it" over "If you use 7 fins instead of 11 and make them a good lot thicker it might be ok" to "we can cast you the outline of the barrel, but you will have to machine the fins..."

Well, in the end I found a foundry in England who was willing to do the castings.

But before I started to make the pattern I had another word with MFC's Mark Cullingworth and hey, could I believe it, they had already made the KTO pattern and had the first barrels cast!!

So I ordered a pair and I was very pleased with them.

Again, MFC can be found at http://www.japbits.co.uk .

So all I have to do is machine the barrels:

This is how they come. Still a bit on the heavy side!
Note the nice oil feed boss, this requires an extra core I think!
Well, first hold it on the top end, set the other end true and machine some 1/2" of the bore. Yes, fear is riding pillion, you can see the block of soft wood under the barrel, but I am not sure it would help. But it does when you open the chuck to fast. Then turn the barrel round and do the same procedure on the top end.
Now, with a big boring tool, I machined 3/4 of the bore, but only to a preliminary diameter of 84mm (my pistons are 85.8mm, but I am not yet sure if I will use these)
For machining the head gasket surface I made a plug to go inside the 84mm bore to hold the near end with a live centre, this is giving some peace of mind! And the same procedure again on the bottom end, of course..
So far so good, now it is milling time for the long long stud holes!
So I'd centre drill them nicely on the dividing head...
...and drill them (first 8, then 12mm dia.)
On all but the two top fins the bore has to be 14mm, so you have to do this from the other end.
I found the cutaways for the stud thimbles needed machining a little as well...
...and the front pot needs drilling and tapping the oil feed boss.
The rear one does not need this, so that one was a piece of cake then!
10/2004: I had the barrels on the engine and it looked nice, but Broughs usually had the barrel necks plated. So I took a deep breath, sand blasted the barrels and polished the necks. I am not sure if I will do that again, grinding and polishing around the oil feed boss is such a nuisance!
Next, I did not want the plating on the nicely machined jointing surfaces (and not inside the bore, of course. So I made nice covers (yes, with recesses cut for the spigots...) that will seal the faces and the bore. And as the plating requires an electrically conductive path to the hook where the work is suspended from, I had to include these funny copper strips. Now the question is just will the platers agree to immerse only the barrel necks?
Well, you might have guessed, they did not. "That didn't work!" they said. hmm... So they plated the barrels all over.
By the way, it was as well that the bore was not finished yet. Despite all my efforts to seal the barrels, I had to find some acid humidity inside, which gave a certain amount of corrosion.
Having the barrels all plated over means that the heat resistant paint will not adhere too well. So I masked everything but the fins off and sandblasted the surface once again to roughen it a little.
Spraying and baking them a little in the stove was straightforward then.

Any kind of feedback to is appreciated
(sorry, this is not a clickable 'mailto:' hyperlink. If you want to write me, please type my address in your mailer. )

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