1964 BS125 twin prototype

[Dave]

Has any one have any photo,s or articles on this particular bike it has a disc front brake?

[kotarojungle]

Hello Dave,

I'm Kotaro from Tokyo, Japan.

I heard about BS125 models from original BS engineer who worked in 1960's.
Bridgestone made two prototypes of 125cc model.
Both models are only for "TOKYO MOTOR SHOW"
Former is for in 1964.
This has inboard disc brake looks like as Lambretta scooter.
single cylinder (steel not alloy), 18 inch wheels.

Later came out in 1966.
This has model number called as "SA-1" just like other models "NA-1" "TA-1 "etc...
This code "SA-1" means  that  it was ready to sell to market but BS tyre had decided to stop to produce new model in autumn 1966.
And never sold to market.
I think it was "the lost new model"
The feature was single cylinder and 4/5 dual gear, 16 inch tyres.
My friend still has original frame of this "SA-1" ....only frame without other parts...

I may have photos of these models.
I will let you see these photos later.

Thank you,

Kotaro

[kotarojungle]

Hello These are photos of BS125 prototype at Tokyo Motor show.

1. BS125 at 1963 Tokyo Motor show

2. BS125 (SA-1) at 1966 Tokyo Motor show

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[sidi]

In looking back through my old magazines, I noticed that Cycle World magazine published a photo of the BS125 (SA-1) at the 1966 Tokyo show. The bike was mounted on a display pedestal. Tubular frame, chrome fenders, white wall tires, just like the photo submitted earlier.

[paul]

The 1963 model has a classic european look. Are there color pictures of either bike? The 1963 bike has double front downtube frame, not very common for a 125 of 1963

[disc_valve]

Dave,

THere was a twin-cylinder 125 prototype, which was displayed at the 1964 (I think) Tokyo Motor Show. It looked like an early development version of what became the 175 Dual twin. Yes, it did have a disc front brake, but it was an enclosed disc (rather after the fashion of Honda's 1980s CBX550). Externally, the brake looked like a normal twin leading shoe drum, but without the texernl cam levers, and with extra ventilation holes. There was an article and small picture in one of the US magazines at the time. I don't hve my magazine collection to hand at the moment, but my own index list suggests the december 1964 issue of Cycle World. I'm sure somebody out there has a copy and to look up and check.

Graham   

[moonpup]

Here's a picture of the one on display @ the 1966 show........


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[paul]

The left engine cover on the 1963 125 appears to be different from the 50,60, 90, 100 Bridgestones that we know. Sure would like to see the right side of 1963 and the left of  1966, 125. Looks like the engines in these single cylinder 125's may be two different  designs.

[paul]

Was there a 150cc single "show bike"?

[disc_valve]

Hi, again.

I've dug out my copy of the Dec 1964 "Cycle World, and have attached a couple of scans from the 1964 Tokyo Motor Show.

The BS125 prototype shows it with the enclosed front dis brake, and dark coloured cylinders (suggesting they are cast iron at this stage. The paragraph in the write-up reads as follows:-

"Bridgestone's 125cc rotary valve twin won't go into production until some time next year (1965), it was learnedAnd just from looking at it, it's a pretty good bet that it will see several changes before it gets to the production line.As it stands now, it has 12.5 horsepower, 4 speeds with a top of "over 74mph", twin carburettors, a monstrous air cleaner, and engine that may be made into a 250ss before it is put on sale. At the front, it has Japan's first disc brake, covered."

Now we know where the 175 Dual Twin came from.

The second scan shows a Lilac C-105 150cc prototype which I think was OHC, not pushrod. Lilac had already restarted production with the Marusho 500 and the smaller twin was, presumably, intended to expand their range. It was quoted as giving 16hp @ 10,500 rpm for a top speed of 83mph. My reason for showing the C-105 pic , apart from the fact that it's a cracking looking little bike, is that I always reckoned the styling had hints of Bridgestone about it. A lot of the Lilac design engineers moved to BS when Lilac originally closed its doors, so it's reasonable to assume that they brought some of their Lilac styling ideas with them.


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[paul]

Thanks for sharing your magazine pages. This machine appears to have a speedometer separate from the headlight shell.

[disc_valve]

Hi, Paul,
   You're welcome - sorry it took me so long to find the magazine (it was in a box in the loft). Well spotted about the speedo - I'd missed that altogether. A separate speedo on a Japanese bike was a bit radical for 1964.

  Also, if you look carefully, I think that's a tyre pump clipped to the frame tube just in front of the rear shock - another early sixties touch that never made it onto the Dual Twin.

I wonder if that bike still exists?
Graham

[disc_valve]

Hi again, Folks.

Just for interest, here are a couple of other Bridgestone prototypes that never made it to production.

The first pair of shots are a couple of 50cc prototypes from 1963. The upper of the two bikes was dubbed the "BS50 Challenger" and was clearly based on the  Champion 3 model (known as the BS "7" in the US). It seems to have been inspired by the Tohatsu "Runpet", but without the style!

The picture below it was dubbed the "BS50 Scrambler", and appears to have a completely new engine and a beautiful double cradle pipe frame. The Japanese caption (which a friend translated for me) says it was 50cc capacity and has a protoype BS90 crankcase. Looks quite Italianesque, and woukld appear to an early stage in development of the BS90.

The third pic is of the BS50 "Chibi", which was displayed at the 1963 and 1964 Tokyo shows. The motor is obviously based on the BS-7, and the rest of the machine was  clearly inspired by the Honda CZ100 Monkey Bike. "Chibi" in Japanese means midget or pygmy - quite appropriate for the little beast.

(The later Rockford Chibi was a completely different machine using the BS50 Sport disc-valve engine. They just pinched the name!)

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[disc_valve]

It's me yet again!

You've probably seen these pics already, but they show the BS200 Mach I prototype from 1967. The production version reverted to normal Dual Twin type styling, which is why it was christened the BS200 Mach II. I reckon this is a pretty looking bike, and it should be possible to build something similar from a junk yard bike - although reproducing those one-piece swept back exhausts might prove a challenge!

This bike was restored by a BS enthusiaist in Japan a few years ago, and was run a couple of times at the "Time Tunnel" meeting in Japan. Having seen the video clip, I can assure it smokes off the start line in fine style!.


I have also got pics of a couple of other BS prototypes which I'll dig out and post some time.

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[RayK]

Great info as usual Graham

Thanks
Ray

[Bikenstein]

Thanks for all the photos and the information. Dave

[paul]

The 50/90 in the middle picture appears to have a silver object behind the cylinder. Possibly a carberator? A piston port prototype from the Tohatsu side of the family?

[paul]

Weren't the later Rockford Chibis powered by BS60 engines?

[RayK]

Paul
I have a Chibi Deluxe (orange) - it has a 60cc Rotary Disc Valve motor. The models for Australia were made and distributed by Tas Tanaka (Japan) who are still in business selling line trimmers and garden equipment.



Not my bike in the video

Cheers
Ray

[disc_valve]

Paul,

The "BS50 Scrambler" does indeed seem to be a piston ported motor, but the general appearance/shape of the engine is edging towards the later BS90 and BS50 Sport. As the caption said it used a prototype BS90 crankcase, that suggests that maybe the BS90 was originally planned as a piston port engine. Do any of our Japanese members have more info on this? (Kotaro-san , perhaps?)

I've dug out a couple of further prototype pics. The first one is a better shot of the original Chibi, taken from a BS brochure given out at the 1963 Tokyo Motor Show. A neat little thing, but perhaps not quite as well finished as the CZ100 Honda.

The second pic is the "BS50 Solo" protoype, shown at the 1967 Tokyo show. This one does look well finished and ready for production. It seems an attractive little beast with a few "modern" touches like the separate rear fender (less chance of frame rust) and I like the basket on the front. I reckon that would have sold well against the contemporary U50 Suzuki and C50 Honda.

In answer to your other post, Yes the later Rockford Chibis did use the BS60 Sport engine, but modified with a different carburettor and only a 3-speed gearbox, but it still produced the original 5.8 hp. That must have provided an interseting ride with your butt only inches fr4om teh deck!

Graham
 

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