Hi Comp Cylinder Heads for 2T and 3T engines

[Guest]

Hi Comp heads

According to Practical British Lightweight Motorcycles by Steve Wilson, the 1961 Norman B4 Sports also had a "tuned 10:1 compression ratio (2T) engine"

It IS confusing!! The Villiers service and parts manual quotes a lower CR. I would suggest that Greeves specified the "tuned" 2T engine with Hi Comp heads and the S25 carb.
I know he re-shaped the barrel porting but I think that was for experimental 2T scramblers.

What was the engine number (spec) sequence for Greeves twins from 1958 to 1962, That might be interesting.

Back in 1984 restored a 25DC and fitted a 3T engine. It took ages to run in but then would show 80+ on the speedo. It had Hi Comp heads. That bike was 435 BDD, which is still around.

[Colin Sparrow]

The 25DB used a 2T with the standard compression ratio and an S22. For the 25DC they upped the CR and fitted an S25. And did away with the alloy cover over the carb.

As sold, the 3T-engined bikes had the standard CR. My 32DC won't do 80. I've tried...

[Rob]

Keith - why not put them on the bike and measure the CR? That way you will have the definitive answer and put us out of our misery not knowing!!

[Guest]

Hi Comp heads.

Keith - why not put them on the bike and measure the CR? That way you will have the definitive answer and put us out of our misery not knowing!!

Good idea, could even fit Hi Comp heads on the 2T to check performance. It ought to feels a bit better or just detonate more?

These are the sort of details that have been lost. Where is all the spec details for Villiers engines?

Keith

[John Wakefield]

Where is all the spec details for Villiers engines?
Keith

Presumably with Villiers Services

[Gordon Barker]

Berts own 2T Fleetwing and High Comp heads.

Just read this thread and thought I might be able to shed a little light on the C. Head subject and also post details of one of my own Greeves.
Five or six years ago I bought a 1956 2T Fleetwing reg. 250JEV on Evilbay from a nice chap in Essex, from memory Thurrock rings a bell.
The seller must have put it on Ebay late at night and luckily for me it just so happened that I had a sleepless night and spotted the listing at some ridiculously early hour next morning.
After gawping at all the documents and provenance stating that it was one of Bert Greeves own bikes and reading and re-reading endless times it obviously was what it was advertised as, so I plucked up courage and pressed the 'buy it now' button. Bingo, the deed was done and all that remained to do was to arrange collection, which I did the next day.
When I saw the bike in the flesh it was a bit grotty to say the least, painted black, later smaller tank fitted, strange looking front mudguard etc etc.
Not having ever seen a Fleetwing before it was a while before the enormity of a rebuild sank in, the only Greeves road bike I had ever owned was a black 4T East or West Coaster which didn't stay with me too long.
Anyway the good bit was all the provenance - copies of the original 1956 entry at first registration to Messrs Invacar, a logbook clearly stating the same info, a Fleetwing brochure with writing in Berts own hand stating that 250JEV was 'my own bike' and amongst other paperwork there was a picture of his collection of bikes including the Fleetwing and also a motorcycle mag of the period stating that this was the works demonstrator cum prototype.
The Fleetwing and others of Berts bikes had been a bequest to Andrew King who I understand was a good friend of his.
That's the history, now what was the question? Now the odd bits.
When I stripped the engine I found that it had the much later 'high compression' heads fitted and would you believe it? It wasn't a 250 because the barrels and pistons were the 3T 324cc variety.
It also had a later manifold and a 1" carb fitted, I presume Bert retro fitted these goodies as they became available later. It did occur to me that they might have been there to provide more performance for what to all intents and purposes was a 2T when being tried out by dealers - perish the thought.
Out of interest the Standard and H. Comp heads are easily recognised and do have different part numbers.
Coincidentally when I collected the bike I asked if there were any spares and was told no, however the seller did list a pair of 2T barrels and pistons on EBay at a later date! Not that I am grumbling as I might have done the same thing.
As I have said previously I have quite a few pictures of 250JEV at various times in its life and there are detail differences between it and later production bikes that I have seen, so I have a little poetic license as far as the rivet counters are concerned! For instance apart from the engine mods I have pics of the front brake hub with and without the central trim between the two brake drums, different mountings for silencers and the dual seat is plain grey material that looks like thin leather.
The dual seat has a very small hole in one side, it's barely noticeable and when I thought of all the famous bums that have graced the seat I really couldn't have it re-upholstered or worse still have the production type blue checked variety fitted.
The frame and engine numbers are both one number before those of the first production Fleetwing for 1957 in the Greeves age guide.
I am abroad on holiday at present but from memory my bike is first registered November 1956. If I have any pics on my iPad I will post a couple separately.
Happy New Year all.
Gordon Barker

[John Wakefield]

East Coaster

Interesting post Gordon, do you recall the reg. or frame number of the East Coaster (yes East not West) you owned. Might be able to tell you if its still around.
John W

[Rob]

Gordon - it could be worth contacting Andrew as he will probably be able to tell you more about the bike if it had passed through his hands. He sold up all his Greeves collection some years ago but has recently got the bug again and bought an MDS scrambles frame and appears as keen as ever once more!

[Gordon Barker]

Ex Bert Greeves Fleetwing 250JEV

John
Yet another try!!
Gordon

[Gordon Barker]

East Coaster reg no.

John
The reg no of the East Coaster I used to have was GNG 541 C. The colour was mainly black - maybe should have hung on to it as it was reasonably tidy! I have since found a poor quality pic of it.
Regards
Gordon

[John Wakefield]

John
The reg no of the East Coaster I used to have was GNG 541 C. The colour was mainly black - maybe should have hung on to it as it was reasonably tidy! I have since found a poor quality pic of it.
Regards
Gordon

Thanks Gordon. Its still on the register with an owner in Northern Ireland. I will send you a PM with his name & address & other owners.

[46T Sprocket]

John
Yet another try!!
Gordon

You where sitting on that broom handle Gordon?

[merlin]

Who said men can only do one job at a time.

[IanCordes]

Having just stumbled across this thread, and being in the process of building a 3T engine, I have photographed the heads. See attached. The combustion chambers measure 2" long x 1" 7/16 at the widest points. They are numbered B12081&2, as can be seen, which my 1960 parts book says are the correct part numbers, and does not differentiate between 2T & 3T. I am guessing they are standard CR, but does anyone have the high comp heads to measure, so that we know what we are looking at?

My engine is a 2T, but I had the cases opened out to accept the larger diameter cylinder spigot on the 3T barrels.

Colin, does your 32DC have an S22, or S25 carb? Originally the 2T and 3T both had the S22, without even any change to the jetting. I am guessing the S25 will give a bit more top-end. The only other difference being overall gearing, with a 25 tooth engine sprocket and 16 tooth gearbox sprocket, compared with 20T and 18T on the 2T.

Does your son still have the spare heads, btw? If so, could you pm me?

Cheers. Ian

[John Wakefield]

All 3T engines had the larger S25/3 carb, the S22/2 was only used on the early 2T engines. Comp ratio for 3T is 7.25:1 & the standard 2T 8.2:1 (although apparently there were some higher comp ratio ones) So the 3T heads will have large combustion chambers, you could calculate the volume with a bit of maths.
Jet sizes for the S25/3 carb are
Main 180
Pilot 35
Needle taper 3 1/2
Groove 3
Slide 3

The /3 designates Standard body, fitted with choke slide operated by cable & handlebar lever

Source of info Villiers Single & Twins by Bacon which does not give details of the S25 on the 2T only the S22. The engine will breath better with the larger carb (hence the later 2T's being thus fitted).
The settings for an S25/6 carb (fitted with rod operated choke) on a 250cc 4T are
Main 180
Pilot 35
Taper needle 3 1/2
Set out 1.94
Slide 3