SM Motorbike thread

lozcb

Member
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12,301
I’ve finally finished the GPz550A1 and have now started looking at the C15. Sadly, it would appear about 40% of it seems to have disappeared over the last 40 odd years, so it’ll be a longer project than I’d initially assumed. Also, of the engine bits that are left, it would appear that in the 20 years it was on the road, it had been thrashed mercilessly by every one of its owners who spent nothing on maintenance. I have to admit, it was my first bike and I was so poor I could afford to buy it, and didn’t spend much on it either. Ironically, I stripped it down back in 1984 in order to spend some money on it, but then I joined the RAF and the job stopped for 40 years! I’m restoring the engine first, and I’ll post some photos up when it’s done.
My first bike was a C15 , standard red black and chrome , cornered like crapp due to a worn swinging arm but one learned to manage it , passed my test 2 days after my 16th birthday and went out and bought a new T120 bonnie , loved it initially but the vibration through the footrests at anything over 70 was frustrating , Mate of mine had just purchased a new Yamaha XS2 650 and it was a revelation so like wise I went out and bought a one Candy orange and black loved it , shortly after family issues due to the loss of my dear old mum saw me leave for to work out in Iran/ Persia in those days where I ended up staying for 5 years and instructed my brother to sell it after 2 years .........Recently i been on a quest to find another exactly the same ...........few and far between and most are basket cases .....but they are about occasionally , this was was at mathewsons auction last year

 

BennyD

Sea Urchin Pate
Messages
14,994
Here's an interesting British bike but with an Innovative Engine from Spain. Get this, it's a 700cc ICE producing 120bhp and only weighs 38kg.
Now here's the interesting bit, it's a two stroke. It's got 8 pistons. It has only four cylinders.

View attachment 123319

I was full of a cold , so I didn't ask more questions about it as I was struggling trying to understand its concept.

Here's a link for you. https://abcmotorcycles.com/innengine-concept/
I’d hazard a guess it’s an opposed piston engine much like the old Deltic locos. As the 2 pistons coming towards each other create the compression you don’t need a cylinder head, and you get a firing pulse every time the pistons reach the top of their stroke. Neat, but it’s not a good looking donk.
 

BennyD

Sea Urchin Pate
Messages
14,994
I’ve been busy with the C15 engine and she’s coming along nicely. The cylinder head has to go away for some machining, a new hardened valve seat for a bigger inlet valve, new valve guides, and a head skim. Then that should be the engine just about done. I’m hoping to get her on the road this summer, so fingers crossed that everything comes together. I’m taking the opportunity to upgrade the internals to SS80 spec which consists of; roller bearing big end, high comp piston, wilder cam, bigger inlet valve, the inlet tract opened up .25” and a bigger (Concentric) carb. All this will take the power from 15 to 23bhp. Not much, but much better! I’ve also raised the gearing and will be upping the wheel size from 17” to 18”. Apart from the mudguards and headlight shell, this will be full Sportsman/Sports Star (SS80) spec.

IMG_2082.jpegIMG_2078.jpeg
 
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lozcb

Member
Messages
12,301
I’ve been busy with the C15 engine and she’s coming along nicely. The cylinder head has to go away for some machining, a new hardened valve seat for a bigger inlet valve, new valve guides, and a head skim. Then that should be the engine just about done. I’m hoping to get her on the road this summer, so fingers crossed that everything comes together. I’m taking the opportunity to upgrade the internals to SS80 spec which consists of; roller bearing big end, high comp piston, wilder cam, bigger inlet valve, the inlet tract opened up .25” and a bigger (Concentric) carb. All this will take the power from 15 to 23bhp. Not much, but much better! I’ve also raised the gearing and will be upping the wheel size from 17” to 18”. Apart from the mudguards and headlight shell, this will be full Sportsman/Sports Star (SS80) spec.

View attachment 124254View attachment 124255
Nice one Ian , and brings back some cherished memories for me Kudos mate , great engine stands by the way , back in 1971 I cheated and sent mine away to Paul Dunstall who was a great engine builder back in those days ..........I believe their still trading
 

BennyD

Sea Urchin Pate
Messages
14,994
There you go Phil, the Kwacker has finally made it out of the garage! It’s covered in dust and an engine case from the other side is in for powder coating but, hopefully, it should be back on the road by Easter. Unusually, all the electronics work as they should which is a bonus as a lot of parts are no longer available.

IMG_2089.jpegIMG_2090.jpeg
 

DLax69

Member
Messages
4,179
iu


Had one of these as a youth...
 

philw696

Member
Messages
25,114
Came up on my memories back in New Zealand 2018 and my trusty BMW G450X that I took over there and did some Good Riding too.
Would love to get back into it best exercise ever :)FB_IMG_1711520351400.jpgFB_IMG_1711520362210.jpg