CG125: why did Honda kill it instead of giving it injection?

[LessIsMore]

I have a couple of things to ask about this little motorcycle, but that’s my main question. Why was this icon of functionalism not updated with fuel injection?

I know the story goes that the CG125 couldn’t be made to meet Euro 3 emissions regulations. I would like to see some evidence for that story. Air-cooled engines are apparently still viable – certainly in the 125 cc class (see the Honda CBF125, which despite its own considerable merits is a poor replacement for the CG125).

And OHV pushrod engines are viable too, since several motorcycles with bigger pushrod engines are Euro 3 compliant. You don’t need variable valve timing to meet Euro 3, as long as you’re not aiming at high specific power output and high fuel economy at low power outputs in the same engine, and the CG was never about very high power. If the CG’s combustion chamber was prohibitively inefficient, which seems unlikely to me given its hemispherical design, fuel economy, and the fact Honda updated the engine several times (compression ratio of 9.2:1 for years, then 9.0:1 in 2001, 9.2:1 again in 2002, and then 9.5:1 from 2004 to its demise) – then why not redesign the combustion chamber with the latest computer modelling tools?

You might argue fuel injection would rob the CG125 of some of its simple mechanical charm, and you’d be right – but it has charm to spare. And fuel injection would strengthen another appealing feature of the CG125: its high fuel efficiency.

The CG 125 brand is still being used in Brazil, but the Brazilian bike has a completely different OHC engine (similar to the CBF125’s, but ironically with a carburettor), faux fairings, an over-designed headlight, a digital dashboard, gratuitous swoops and creases all over, etc. Basically, it’s nothing like the real McCoy.

There’s a CG125 in Pakistan too (by Atlas Honda for just ~€760 new!). But of course it wouldn’t meet Euro 3 emissions standards. However, some small air-cooled bikes with carburettors in India – such as the 110 cc CB Twister (PDF) – meet Bharat Stage III emissions, which are equivalent to Euro 3.

I know a lot of people look down on the CG125 and treat it as a beginner’s bike. But there are others who appreciate its greatness. Either way, millions and millions have been sold. And that brings me to my second question. Where are the books examining this bike in depth? The CG is to motorbikes as the Volkswagen Beetle is to cars, and hundreds of books have been written about the Beetle. Does anyone know of a good book that covers the Honda CG125 – its development, history, sales, model variations around the globe and across the decades, etc.?

And finally, given that the CG is dead, what bikes in Europe are left that might appeal to people who appreciated the CG?

Thanks.

[MarJay]

Because you can't just 'add fuel injection'. It would need a complete redesign which is effectively what the CBF125 is really.
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+1^
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[LessIsMore]

And why can’t you just add fuel injection? Lots of manufacturers have done that to other bikes. Even IMZ-Ural did so for its 2014 sidecar models – and IMZ-Ural is a tiny company with next to no resources (the Ural fuel-injection system was actually designed by ElectroJet, Inc. in the USA, with mostly Bosch and Delphi parts).

Even if you couldn’t just add fuel injection, the CBF125 is not an adequate replacement for the CG125. It is an adequate – maybe excellent – replacement for the CG125 as a learner’s bike and for people who don’t care about aesthetics or design, but it doesn’t appeal as strongly as the CG125 did to the wider market.

The CG has timeless style due to its functionalist design, and good quality materials and construction. It’s pared back and stripped to the essentials of motorcycling. The CBF125 is a sporty thing, half-made of plastic, with pointless swoops and arbitrary design throughout. It has lots of unnecessary clutter. It’s neither sophisticated nor stylish, merely transiently fashionable to undiscerning (and probably mostly young) buyers.

Mechanically, the CBF125 is still very interesting, of course. It’s a Honda. And that brings up another possibility. A CG simply fitted with a CBF125 OHC engine would be vastly preferable to me than the actual CBF125 (which is never going to be a classic).

[trevor saxe-coburg-gotha]

I *think* suzuki "just added" FI to the vanvan. Obviously they did a bit more than that butcha get me.
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[MarJay]

Well you obviously know the answer already so there is no point replying....

However my twopenneth is that you can't 'just' add fuel injection. You need to add a full electronic package to manage emissions, including perhaps a catalytic converter, a lamda sensor and various other electronic gubbins in order to meet the emissions targets. If the engine is not a very efficient design anyway, then maybe even with this it still cannot meet the targets. Maybe it fails on noise targets? Maybe Honda decided that the engine was at the end of its useful development life? It's hardly a masterpiece of Engineering in the first place. It's a basic pushrod engine in a basic chassis. Dragging its life out further was not going to benefit anyone really.
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Teflon-Mike]

First, Fuel Injection isn't the magic panacea to all automotive ailments.
A properly set up, properly maintained carburettor is a very efficient device. Fuel injection, however is cheaper. To make, to develop, to tune, and to maintain. With closed loop feed-back its essentially self maintaining until the injectors wear out, and you dont need a box of little brass jets and thousands of man hours to try and find the right combination to make an engine work half well.

As to the emmissions; you have answered your own question; the CG125 push-rod engine DOES actually have a relatively high specific power output.

10bhp from 125cc, is 80bhp per litre. That is as much as many of the more modern, overhead cam, fuel injected, water-cooled commuter twins, making 65bhp or so from 650cc, in order to meet 'emmissions'.

The 'push-rod' MT01 is 1600cc and only delivers 90bhp... 56bhp per litre. Its actually less power per cc than an old push-rod mini engine! What else still has push-rods? Harleys? Dont seem to quote power any-more; but an educated guess says bhp/l Yamaha get from the MT01 would be good for any of them!

Moto-Guzzi V7, I think is still push-rod; gives a good idea why they couldn't viably detune the CG to keep it in production. V7's engine is the last evolution of the old V50 engine, bored from 490cc to 744, given fuel injection and four valve heads to make 49bhp... LESS than the original, slide carb, two-valve 500!

But hey, doesn't really matter; as a 'middle-weight' they can hog out the displacement to keep power 'acceptable'.

But you cant do that if you are making a 'learner-legal' that HAS to be under 125cc. And detune a CG125 to that sort of level, you are going to be looking at moped power, 5-6bhp, and a bike that would struggle to do 50mph.

As to the CG legend; no, the Honda C70 is the motorcycling equivilent of the VW beetle, in terms of being the most popular motorvehicle ever made, and STILL made.

CG was actually something of a dead-duck at birth. Sochiro Honda loathed two-strokes, and insisted they make four-stroke motorcycles every bit as good as others made two-strokes.

The Honda CB125 single, of the late 60's and early 70's, was a pretty decent little bike with then 'advanced' overhead cam-shaft. Made about 12bhp, but in western markets was let down for not being all that sporting, against two-stroke competition; in Asian markets was let down by poor standards of maintenance that saw them quickly wrecked with seized cams.

The CG125 was the suggested solution for asian markets; a retro engineering job on the OHC Single engine going back to push-rod technology to avoid siezed cams if the oil wasn't changed. Project co-incided with the partnership with the Brazilian government to open a factory in South America. And the CG125 would have been an utter FLOP had it not been for the politics of that deal, as the bike cost Honda more to make than they could sell it for, and not many wanted to buy it! Apparently they had a huge over production in Brazil in the early years; tolerable only because of the Brazilian Government agreements.

Were it not for the politics, the model would have been dropped; when Honda capitulated to two stroke dominance and built the H100, to do the same job; which did do it better and made the company money.

It was only when emission legislation started to hurt the two-stroke position that the CG was remembered, and that co-incided with the euro-harmonisation of licence laws, and in the UK a minimum capacity limit of 120cc being set for 'test' bikes; meaning you could no longer turn up and get a ride what you like licence on a C90 or KH100; had to be a full 125cc machine.

That was when we started seeing CGs in Britain in any number, as Honda introduced it into the catalogue to replace the 100cc two-strokes, the mainstay of the training schools, who wanted cheapness and ease of maintenance, like a two-stroke 100, over 120cc, when they couldn't buy KH125's any-more.

Subsequently, Honda re-wrote the CG125 history as if it had ALWAYS been the paragon of low cost commuter virtue and durability, as if it had always been a 'star' of the learner-legal range! Or in other words, they put a new 'spin' on the flop that the bike was to begin with!

I don't know of any books; BUT Honda have devoted a lot of thier corporate web-site to their re-written version of the CG history.

Other bikes that might appeal to CG-ista? Well, the spritual successor the the CG is the Yamaha YBR125, loosely based on the old SR125, with less cruiserified styling, but I believe a derivative of its OHC engine. Similarly, the Suzuki GS/EN125; again OHC single, which is probably as old in design as the CG's engine.

But what's wrong with a genuine CG is that's what you like?
apart from fact that you cant buy a brand new one, and because of the legend, people seem to want more money than they are functionally worth for second hand ones? But they are still hardly rare or expensive.
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[bikersupermot...]

its not killed at all. where you get that from?

you can import a new one from asia - im just back from india and they are all over the place there, on the roads and in the showrooms and still being advertised on tv there - the Honda Hero.
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[LessIsMore]

[stinkwheel]

I bet they are not so eay to assemble in a fully automated factory.

There will be bits in there that need a nimble-fingered Japanese factory worker to poke them into place and hold them there while another bit is inserted.

Pushrods themselves being a classic example. You've got to get them in at both ends.

Also, nobody would buy the CBF if the CG was still on the go.

You CAN just bolt FI onto a bike that wasn't originally designed with it. A mate of mine is an expert in FI and was mad keen on designing a bolt-on kit that would convert the classic bike of your choice to FI. He was looking at my enfield with it's newly fitted amal concentric and utterly missing the point while he was talking about this. Wouldn't surprise me at all if he turns up on his T140 one day with a homemade FI system fitted.
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[Teflon-Mike]

[LessIsMore]

I didn’t see the other replies when I posted the last time. Thanks for all the comments, by the way.

[Rogerborg]

[Kickstart]

Hi

Suspect that one issue to getting it to run cleanly is the single cam lobe used for both intake and exhaust. Somewhat limits any change in cam profile (timing can be fiddled with changed rocker arms), although a good idea for reducing build costs.

Think part of the issue with the CG125 is that it wasn't designed for those who cared about "aesthetics or design", and the CBF is aimed a touch more for those. Market is a bit more style based than when the CG125 was launched.

All the best

Keith
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[27cows]

Would imagine Honda finally woke up and realised what a horrible pile of cack the CG was
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[LessIsMore]

[Nobby the Bastard]

I passed my test on a CG125 twenty years ago. It was shite then and it would be even more shite now.

(Borrowed the CG for my test becuase my RG gamma couldn't do the manoeuvres)
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[Pol Anorl]

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[Teflon-Mike]

[andyscooter]

yes you can thats what cake is for

will prove this later as mum made three yesterday and im going over
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