Hi Guys,

I was wondering why manufacturers didn't figure out some way of standardising on pistons for WD mounts?

Take the 350cc Enfield WD/C SV and the WD/CO OHV machines for instance. Surely it would have made sense, both practically and economically, to use the same part in both machines?

Or am I over-simplifying the situation? I do expect to be shot down in flames on this one, so go for it!

Bruce

Yes it's not as simple as that Bruce. Although the C and CO share the same bore and stroke dimensions 70 x 90 and the same flywheels and conrod. The barrel hight's are quite different which would call for a different gudgeon pin location in the pistons.

Apart from some engine and possibly gearbox internals, I think there is very little else that is interchangeable between the two models, apart of course from standard items that could go on any bike. Ron

email (option): ronpier@talk21.com

Thanks for that Ron.

I did notice that the gudgeon pins are at a different level - and I see that the top piston ring is closer to the crown on the one as well.

Bruce

Bert Hopwoods 'modular' range of bikes that were designed in the early 70s were the nearest they got to 'standardisation'...

These were based around a basic single cylinder engine which formed the basis for engines up to five cylinders..twin, triple etc...

All the engines shared a large number of internal components (valves, springs, con rods, pistons etc.) and would have been both cost effective and a production engineers dream...

They illustrate well how Hopwood thought beyond a single model to a whole range, production and manufacturing costs and and also to future development.

The whole project was still born as the BSA board didn't have the sense to invest in their own future...

Frankly I'm amazed that no manufacturer I am aware of has gone down this route...Cost savings from manufacture right through to the spares kept on a dealers shelves would be substantial when compared to a conventional range of bikes...

To further illustrate Hopwoods advanced thinking the larger models employed a single sided swinging arm...Nearly two decades before that was seen on a production bike...Ian

email (option): ian@wright52.plus.com

Cheers Ian - as you point out, spares standardisation makes huge sense.

Hopwood must have been quite a "thinker" for his day, which probably annoyed a few people around him. Human nature - folk don't like to be shown up, do they?

Bruce

I think the early range of Hinckley Triumphs did use (at least in part,) a modular system but as that's ancient history now too I wouldn't swear to it!
REgards, Mark
(Just to explain, my interest here is through Enfields, I nearly bought a WD/CO project from a chap who after showing it all to me then "decided to do it up myself". As you probably guessed it's still in pieces but we live in hope...)

The triumphs over many years kept the same wrist pin diameter and compression height, 1" main shafts were common on many brit bikes and Norton es2 and 16H pistons will interchange (the SV piston has the humpy piston ?).

The trident/rocket three was basically a three cylinder T100 Daytona and virtually all postwar 500/650/750 gearbox internals can be interchanged to some degree.

But I'm afraid you have to go Japanese to find part commonality.