Big Bore Villiers Engine Units

[08colin]

Anybody tried or have knowledge of the big bore kits for the villiers

A series bottom ends.Ive been told that you can get them out to

350cc is this correct.Who makes these conversions and what sort

of a price,will the crank/big end, clutch and gear box stand the extra

power and can you get away with rejetting standard amal carb.

Is it a worth while conversion cos i'm thinking along the lines of

building a jimmy with one of these engines.

Colin

[totalshell]

for me i'd ask the question how many and who are using them. what are the top riders using. is the plain cast iron barrel enough.

caertainly at yorks classic and red rose i dont see any 'big bore' villiers ( and those boys are ultra competative with some really good engineers amongst them. top riders seem to prefer the alloy barrel but ask enough questions and you may find its more of a fashion thing than performance based. there are plenty of v. succesful riders just using the std cast barrel and many of the old works boys said they prefered it to the alloy.

thats not to say dont go ahead with it but all those old boys cant be wrong..

[08colin]

Hi Total shell point taken, but when you hear of and see cubs

anywhere from 200 to 290cc, bsa units anywhere from

250 to 490cc, bantams stretched anywhere up to 230cc

the old 8 and 9e's opened up to 225cc there must be something

to this over boring lark and i was basically thinking aloud on what

is available for the A series villiers.I have a bottom end sat here

and need a top end for it and looking at some of the prices they

asking for cast iron barrels let alone the alloy square barrels i was

interested to find out what else is available that is why i posted

the question. thanks again Colin

[farmer58za]

08Colin

Co-incidentally, with my Cheetah trials bike, I received a spare 350cc REH barrel for the 37A motor. According to Robin Humphries the REH unit uses a Greeves piston and I imagine it just bolts in.

Regards

David

[08colin]

Hi David I presume you haven't actually run your motor with

the big barrel any idea whether it's worth considering a big

bore conversion and any idea the cost of these conversions.

Who is now making these kits.

thanks again Colin

[charlie prescott]

Hi Guy's

Hi Colin. take a look at the Greeves web site, and I seem to remember that Norton -Villiers up north do a DOT barrel as well.

Hope this Helps.

Regard's Charlie.

[farmer58za]

I dunno Colin.

The bike is in kit form and it came with the 250 and 350 REH Barrels plus the original square one (250 REH was fitted) . I'm quite happy with a 250 trialler - the only complaint about my Bantam is that sometimes you need to wind it up to get up a steep slope. I only ever rode a 1978 350 montesa. Torque like crazy.

I have yet to see another REH barrel. Maybe you need to troll the autojumbles or (dare I say it) Ebay.

Regards

David

Hi David I presume you haven't actually run your motor with

the big barrel any idea whether it's worth considering a big

bore conversion and any idea the cost of these conversions.

Who is now making these kits.

thanks again Colin

[woody]

Any topic like this is subjective, opinions will aways differ but, for what's it's worth I really don't think there is any need for a big bore Villiers.

It wasn't a standard fitment to a Villiers so there are no baseline settings, once you've got one, from whatever source, there will then be endless time messing with it trying to get it to run right as it's unlikely to do so right away. If there is some sort of fundamental design flaw that you don't know about, port sizes, port timing, compression ratio etc it'll never run right and you'll be trying to tune something that isn't tuneable. In the end for what? More power than you'll never need in classic sections.

A 250 Villiers with electronic ignition, decent exhaust and airbox and good (ie; not worn out) carburettor will have more than enough performance. No need for TY or GasGas porting, reed valves etc. I borrowed a friend's bike for the Manx Classic this year fitted with a standard 37a, DMW barrell and head with Villiers piston, decent exhaust and airbox, motoplat ignition, amal mk1 carb - nothing else. It was fine, performed very well, good pick up off idle, torquey, revved out well with enough over-rev to give a long flexible long bottom gear. It was the first time I'd ridden a Villiers engined bike since the 9E piece of crap we learnt to ride on as kids and I was impressed with it. If it was mine I wouldn't want to change anything on it.

I know someone who was running a 350 James a few years ago with a nikasil barrell and modern piston. He gave up with it in the end as it was too much hassle to get it right. Save yourself a lot of time, expense and grief and use a 250. They have all the performance you'll need.

[sparks2]

Hi Colin

Yes, in the main I would agree with the former contributers. No one is now manufacturing a big bore kit for the Villiers A series probably for the reasons stated by Woody.

Maurice Brayford has a Moto-Cross Motors big bore conversion fitted to his James. But he used to work for John Burns at Moto-Cross Motors

in Oldham so he should know what he is doing. I believe Peter and Derek Carson in Derbyshire have recently spent a lot of time trying to get a big bore kit to run properly

and gave up on it, maybe Old Trials Fanatic knows more? With the normal 250 alloy conversions, don't forget, there is a significant weight advantage. I save 9lbs with my conversion compared to the CI Villiers barrel. The weight is fairlly high up on the bike so I believe the saving is significant.

Regards

Sparks2

[stickinthemud]

I remember riding a Cotton with a 350 conversion in the late 60's.

The vibration caused by the heavier piston was intolerable.

[08colin]

As i mentioned in an earlier post i have a 32a complete bottom end

sat here and no top end iv'e had a whisper that i know where there

is a 350 top end layed by what i can find out it is a square barrel but

the top end of the barrel including the head sticks out 25-30 mil wider

than the bottom square of the barrel i don't know who made this conversion

or what to pay for it if at all any advice on price and who made it and whether

it's any good would be welcomed.

Colin

[old trials fanatic]

FWIW dont bother. The conversions are more trouble than they are worth. Pete Carson has spent ages fiddleing with his. In fact i think he may have given up and sold the bike. I know a friend was going over to have a go on it looking to buy.

As Woodie and others have said the CI or alloy , my preference sharper power delivery, barrel is more than enough.

Simon Bateman is in the process of having some new Greves TES replica ones cast so to me it's a no brainer.

If you know where there is a 350 barrel and head going cheap theres probably a good reason.

Whatever you decide good luck.