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Venom Alfin Cylinder Finish
#773583 05/13/19 5:00 pm
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Hi.
I am completing some work on the top end of my 1957 Venom and I am trying to find out the best finish to apply to the cylinder. It looks like it has been painted but this has yellowed and is very stained. Should it be painted? Can you powder coat it? Should it be silver or black.
All comments greatly appreciated.
Thanks, Stuart.

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Re: Venom Alfin Cylinder Finish
Stuarts7 #773706 05/14/19 5:12 pm
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An "Alfin" cylinder is aluminum and they are not painted or coated in any way (usually). The cast iron cylinders are painted, usually silver on Venom/ Viper/ MSS. Probably no reason you could not powder coat an iron cylinder.


Laurence Luce
Re: Venom Alfin Cylinder Finish
Stuarts7 #773741 05/14/19 11:29 pm
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Well, I'm not sure about that Lawrence. I think most cast iron cylinders were painted black. High Temp obviously.
Also, my ALFIN barrel is painted silver around the base where the cast iron protrudes below the cast on aluminium 'muff' (Though I think mine is a KTT barrel).

Re: Venom Alfin Cylinder Finish
Stuarts7 #773791 05/15/19 1:35 pm
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Venoms , Thruxtons and Vipers with cast iron cyliders were painted silver by the factory. many owners painted them black to hopefully improve heat loss.
I have used tremclad aluminium anti rust paint on cylinders and the cast iron potion of brake drums with no problems.
I do not like the idea of powder coat on cylinders, wrapping a cylinder with an plastic watertight and air tight layer seems all wrong.
what do you think?

Re: Venom Alfin Cylinder Finish
Stuarts7 #773811 05/15/19 4:23 pm
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I have a '61 MSS and a '58 Venom that both came to me in largely original, unrestored condition. Both cylinders are silver. The silver shows oil leaks and grime a lot more than black would so just on that basis, if appearance is an issue, I could see a rational for going black. As to concerns about plastic coating a cylinder, isn't that what your'e doing with any paint ?


Laurence Luce
Re: Venom Alfin Cylinder Finish
Stuarts7 #773817 05/15/19 5:51 pm
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The is a definitive youtube showing the difference in heat retention between a bare Norton uncoated twin barrel and a powder coated barrel. It was only just detectable, ie no difference in real life.

https://www.youtube.com/watch?v=rWNs0f5Ly9k

Re: Venom Alfin Cylinder Finish
Stuarts7 #773845 05/15/19 11:12 pm
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Thanks for all the comments. So can anybody see a problem with me having the cylinder vapor blasted and leaving them like that. No paint or powder coating. I like the idea of black so it stays looking nicer (no oil stains) but I also want the bike to look correct. My cylinder was painted silver but who's to say when and by whom that was??
Thanks, Stuart.

Re: Venom Alfin Cylinder Finish
Stuarts7 #774120 05/18/19 9:15 pm
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No issue whatsoever with leaving the Alfin barrel unpainted. I believe the Alfins should be left unpainted, my Velo is that way (my spare engine also).


Buells and Brit Bikes
Re: Venom Alfin Cylinder Finish
Stuarts7 #774165 05/19/19 7:42 am
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Yet my Alfin barrel needs paint below the alloy finned area.
(My aluminium outer 'muff' casting around the iron barrel) does not extend all the way down to the cylinder base.
So the area below the lowest fins and a little more more below, is 'naked' cast iron, which would rust if left unpainted. My barrel is new, factory fresh, albeit a KTT cylinder.
I'm not saying factory VMs etc are the same as my KTT Alfin barrel. It would be interesting to know the difference.

Cyclone, where does your aluminium outer 'muff' casting finish? Does it extend all the way down to the cylinder base flange or not?
My barrel is the Alfin (Welworthy made) barrel. The cylinder bore and barrel is iron, extending down to and forming the cylinder base flange, the aluminium 'muff' is cast around this.

But it is the iron 'inner' that bolts down to the crankcase. The aluminium 'muff' doesn't extend all the way to the flange.


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