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21
Identify these bikes! / Re: Precision Big4 frame ?
« Last post by cardan on June 24, 2026, 03:31:13 AM »
This is how to squeeze a 4 1/4 Precision into this frame - pretty brutal, just bend that down tube a bit... The engine is the 1912-only model, quite different to the later Big Four engines. The bike is a Melbourne-built Morton.

Looking closer at the surviving frame, the engine plates with it are the Precision type, rather than the Fafnir type (which also picked up on a lug high on the crankcase near the back of the cylinder).

Frame number tells all.

Leon
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British Bikes / Re: Coventry Eagle 1932
« Last post by 33d6 on June 24, 2026, 03:26:21 AM »
You'll note also the Amal carburettor, not Villiers. These are fairly easy to find as it's more or less the generic Amal of the time for all the 150cc four-strokes made then. Royal Enfield, New Imperial, Excelsior, Triumph, BSA and so on. As the UK introduced a major tax break for up to 150cc machines in the early 30's, sooner or later every firm and their dog seemed to have a go at making a nifty 150. There's more survivors than you think but they all suffer the same equal restoration cost problem. It costs much the same to restore a 150cc bike as it does to restore a larger one so enthusiasts spend their money on the bigger machines letting the 150's gather dust. Pity about that. They make a refreshing change from yet another 500 sidevalve single.
The trick lies in finding out the jetting specifications and so on as it should be different from those used in four-stroke applications. I may have it somewhere but Amal carbs don't figure much in my world so I'm unsure. 
23
Identify these bikes! / Re: Precision Big4 frame ?
« Last post by cardan on June 24, 2026, 12:33:34 AM »
Very nice. Could I have the frame number please? It is likely on the right side of the seat lug.

Re engine: depends a bit on the frame number. The early version of this frame was usually fitted with the overhead-inlet-valve Fafnir single, thus the very narrow lugs. When Healing gained access to Precision engines, they fitted 500s to this frame using aluminium spaces between the frame lug and the engine plates. Some of Healing's customers - maybe even Healing themselves - fitted the 4 1/4 hp Precision (600cc) to this frame, but to do so the front down tube had to be bent forwards because of the bigger crankcase. It would seem wrong to do this now. If a 600 Precision were fitted to this frame it would have had Precision on the magneto chain case. PRECISION BIG FOUR was a Healing trade name that was only used on the "new" bikes (in new frames) that came out around August 1913.

Anyway, I can guess engine based on frame number, as Fafnir engines in this frame stopped when the new Peerless frame came out in August 1912, but Precisions continued. It's such a nice frame - many have been cut down to lower the seat - that it would be a pity to put the wrong engine in it. Missing petrol tank is Davison and hubs were Chater Lea.

Leon
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British Bikes / Re: Coventry Eagle 1932
« Last post by cardan on June 24, 2026, 12:13:14 AM »
8D or (more likely, based on numbers built) 9D.

Here are the Cov Eagle images 33D6 refers to, in Radco's book. 1933, 150cc. The inlet manifold looks even longer than the one posted above!

Leon

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British Bikes / Re: Coventry Eagle 1932
« Last post by ramwing7 on June 23, 2026, 03:35:22 PM »
Any idea which Villiers engine this is?
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Identify these bikes! / Precision Big4 frame ?
« Last post by R on June 22, 2026, 11:18:28 PM »
Can anyone identify this ?

Would this be suitable for a Big4 engine / build ?

https://i.postimg.cc/tgT7Zg3Z/veteran-frame.jpg
27
British Bikes / Re: My 1951 G2 Trials
« Last post by murdo on June 22, 2026, 08:04:39 AM »
Well update on the nuts. I could not find the correct sized bar at any of the local steel merchants, so even looking at internet sellers gave no joy. The price of a tap to use once or twice was prohibitive so I just counted up the number I needed and added then to my Hiscocks order. Still not cheap but will be the right size and should fit with no dramas.
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British Bikes / Re: Coventry Eagle 1932
« Last post by R on June 21, 2026, 10:19:28 PM »
Villiers loved those curly-whirly manifolds.
Keep your eyes peeled, this one is about the exact mirror image ?
Good luck.

29
British Bikes / Re: Coventry Eagle 1932
« Last post by ramwing7 on June 20, 2026, 02:58:31 PM »
Thanks folks.  You have to love the vintage motorcycle community.  No matter how unusual the bike is or how strange the problem, somebody out there has ideas and tips they are willing to share.
I'm off pursuing some of these now.
Thanks.
30
British Bikes / Re: Coventry Eagle 1932
« Last post by R on June 20, 2026, 03:38:59 AM »
Quote from: 33d6 on June 19, 2026, 02:58:03 AM
'The Vintage Motorcyclists' Workshop" by Radco contains a full double page photo

Split across 2 pages it must be noted. The manifold is slap bang in the page join !
All the online scans are awful in the picture dept, they must have scanned a photocopy

I've done some lost wax casting.
Doing a curly plaster central core of the actual gas pathway and coating it with wax to a suitable depth and then coating the whole
shebang in more fireproof plaster is possibly the simplest method ?  You'd have to find a foundry that does this type of casting.
Simpler than it sounds, and cheaper as a one off than making moulds and core moulds.
The cast metal very accurately replicates the finish on the wax - so you could inscribe your image on it !
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