Re: '54 Dommy 88 inlet manifold

John Shorter previously wrote on Tuesday July 26th at 17.37hrs:

I have a '54 Dommy, which has gradually been restored to 99% "As New" condition. One remaining problem is the inlet manifold/carburettor. The inlet bores into the head are 1" dia. However, at some time a 1,1/16" monoblock has been fitted (Possible from a 99 model?). I am concerned that this is spoiling the gas flow, where the inlet manifold meets the restriction into the head. I would imagine a '54 inlet manifold to be as rare as hen's teeth (although the correct carb is easily obtainable). I have considered reaming the head to match the manifold now fitted. Is this a "Bad idea"?

Hello John,

I think you are lucky that the previous owners didnât enlarge the inlet ports. In fact itâs amazing they have survived so long. One reason there are so many iron heads knocking around is that as soon as the ally head was introduced, that was the obvious way forward for the go-faster boys. Here was a frame that was almost identical to a Manx, but powered by a gentle twin.

I have never thought the 88 DeLuxe manifolds were rare. You still see them in odds & ends bins at autojumbles. Just make sure you have a go/no-go gauge in your pocket. A turned down piece of dowel would do.

Do what you like, but my opinion is that you may lose a lot of the torque from your iron head 88, if you open the ports up.

The same thing has happened to a lot of the 650âs. They originally came with sleeves fitted, from the outer ends of the individual manifolds, that extended right into the ports as far as the valve guides. Lots of amateur tuners would pull out those sleeves, thinking they had found an easy way to âget more flowâ. When they had finished their special, with its rear sets, ally tank and megaphones, the racket made them feel like theyâd now got another 10bhp, whereas theyâd more likely lost as much and had to rev it like hell too keep up with their mates.

A lot of Goldie engines have gone flat for the same reason. People noticed the step at the port and got to work blending it.

Although a restriction may seem illogical, it would actually act as a venturi and speed up the in going charge.

The 88 De-Luxe should be a sweet little motor really. Smooth running and a pleasure to ride, with its low compression. A 1 3/16" monobloc would probably be ok. You would be able to run it very well on a 1â monobloc as well, if you donât have a 276.

Paul

John Shorter previously wrote on Tuesday July 26th at 19.36hrs:

Thanks for the advice Paul. I think I will leave the carb set-up "as is" for now. As a teenager, in the fifties, I owned a '53 88. The '54 model does not seem to have the same performance (but then I was several kg. lighter!).

OK John, But wait and see what the real experts say about it.

By the way, I would have edited my first reply, but we can't do that on this message board.

I meant to say 1 & 1/16" monobloc would probably be ok, not 1 & 3/16".

The '54 model was identical mechanically to the '53 as far as I know. So if everything is set up okit should be the same.

(I hear what you say though. I was 10st when Iused to tear around the oval. Now I would stand more chance by just getting in the way!)

Paul

Previously wrote:

John Shorter previously wrote on Tuesday July 26th at 17.37hrs:

I have a '54 Dommy, which has gradually been restored to 99% "As New" condition. One remaining problem is the inlet manifold/carburettor. The inlet bores into the head are 1" dia. However, at some time a 1,1/16" monoblock has been fitted (Possible from a 99 model?). I am concerned that this is spoiling the gas flow, where the inlet manifold meets the restriction into the head. I would imagine a '54 inlet manifold to be as rare as hen's teeth (although the correct carb is easily obtainable). I have considered reaming the head to match the manifold now fitted. Is this a "Bad idea"?

Hello John,

I think you are lucky that the previous owners didnât enlarge the inlet ports. In fact itâs amazing they have survived so long. One reason there are so many iron heads knocking around is that as soon as the ally head was introduced, that was the obvious way forward for the go-faster boys. Here was a frame that was almost identical to a Manx, but powered by a gentle twin.

I have never thought the 88 DeLuxe manifolds were rare. You still see them in odds & ends bins at autojumbles. Just make sure you have a go/no-go gauge in your pocket. A turned down piece of dowel would do.

Do what you like, but my opinion is that you may lose a lot of the torque from your iron head 88, if you open the ports up.

The same thing has happened to a lot of the 650âs. They originally came with sleeves fitted, from the outer ends of the individual manifolds, that extended right into the ports as far as the valve guides. Lots of amateur tuners would pull out those sleeves, thinking they had found an easy way to âget more flowâ. When they had finished their special, with its rear sets, ally tank and megaphones, the racket made them feel like theyâd now got another 10bhp, whereas theyâd more likely lost as much and had to rev it like hell too keep up with their mates.

A lot of Goldie engines have gone flat for the same reason. People noticed the step at the port and got to work blending it.

Although a restriction may seem illogical, it would actually act as a venturi and speed up the in going charge.

The 88 De-Luxe should be a sweet little motor really. Smooth running and a pleasure to ride, with its low compression. A 1 3/16" monobloc would probably be ok. You would be able to run it very well on a 1â monobloc as well, if you donât have a 276.

Paul

As Paul states, the 54 '88' is a sweet engine but it should be fitted with a 76AK/1AT 1''bore carb. Manifolds are not that scarce, but if you struggle in obtaining one for originalitythen let me know as I probably got a spare,

Regards, Paul Webb.