Logic?

somerstown · Post by **somerstown** » Mon Aug 06, 2007 8:52 pm

What was the logic behind the changes made between the 250 and 350cc Lightweight models? As far as I am aware the frames are different, the rear wheel, the rocker cover, primary chain and cover, and no doubt others could add to that list?
It seems unnecessary expense in production when they could just have changed the barrel and piston. (and possibly the cylinder head?)
I realise at this remote point in time that might be difficult to answer, or maybe someone can shed some light into AMC thinking at that time?

itma · Post by **itma** » Mon Aug 06, 2007 9:00 pm

In a word
desperationEdited by - itma on 06 Aug 2007 8:01:20 PM

CR · Post by CR » Mon Aug 06, 2007 11:11 pm

In the late fifties the legal learner limit was 250cc. Other manufacturers had 250's. BSA had pre unit C10/C11/C11G/C12 and then the unit 250 which many learners purchased - the C15. Triumph had the 200cc Cub, Ariel had the rather long-in-the-tooth pre-unit 200cc Colt, Velocette had the 200cc Valiant (OHV) and the water cooled SV LE's, Royal Enfield came out with their Clippers and then of course there was a whole host of 200 - 250cc strokers from Francis Barnet, James, DKW, Cotton, Greeves, Royal Enfield, BSA etc. Whilst AMC owned the FB and James names in 2T, they didn't have a modern 4S 250.

Enter the G2/Model 14 Lightweight in 1959. It looked like a unit contruction, but wasn't - and it wasn't lightweight either. However, it did match the power of the C15 Star (a favourite learner) and in the same way that the C15 was stretched to 350 and beyond (B40 et all), so the G2/M14 was stretched to 350 in the G5/M8.

Whilst often ridiculed and used as a shed-doorstop, the 250CSR motors really motor - and so does the 350! Trouble is, the Japanese were just around the corner and the rest, as you probably know, is history.

Biscuit · Post by **Biscuit** » Tue Aug 07, 2007 12:47 am

What I find illogical is that new patterns had to be made for virtually every engine casting but they didn't take the opportunity to design a true unit engine.

Don Madden · Post by **Don Madden** » Tue Aug 07, 2007 3:57 am

AMC proved that the unit construction idea is unsound. They produced a stroker unit 250cc & it was terrible! Thus the logic of the opening statement.

Cheers, Don.

bag-o-nails · Post by **bag-o-nails** » Tue Aug 07, 2007 8:23 am

Terrible!! and this from the land of the two wheeled car
i will have you know my 250 csr starts first time and goes like stink How many usa
marquees are there let me see, Harly Davidson
wasn't it!
cheer's Phill

Biscuit · Post by **Biscuit** » Tue Aug 07, 2007 1:35 pm

Don, I feel I'm being led into a leg pull here, surely the alleged difficulties with the AMC two stroke had nothing to do with the fact that it was unit construction

itma · Post by **itma** » Tue Aug 07, 2007 1:48 pm

and AMC in France proved it was a sound idea. properly designed I see little overtly wrong with the idea, you just need to learn how to fit a gearbox

chris kelly · Post by **chris kelly** » Tue Aug 07, 2007 8:24 pm

Hi,

It seems to me that the 250 received really good Road Test reports, at least in the book that I have, there is quite a few , and lets not forget that Peter Williams and Tony Woods won the Lightweight class of the Thruxton 500 mile race.

They were up against Continental and Japanese production machinery and that race, I think, was in 1964.

My 250 was really good to ride.

Chris.

somerstown · Post by **somerstown** » Tue Aug 07, 2007 9:39 pm

I meant no disrespect to lightweights, I am pleased with my own 350. But it seems odd changing so many parts on two almost identical models. This must have added an unnecessary amount of cost to production. Surely to have kept as many parts as possible the same would have saved on cost which were already raised by putting two different badges on the same bikes?