Building a Scrambles G80 Bitsa

[RichardS]

Hi J-B,
your's looks very similar to mine and I had already decided I would add a bolt through to the engine plate as an aditional brace very much as you have. Three little screws at the front will have a tough job on their own to stop the whole case flailing about with vibration. And yes, it only just clears the swinging arm.

Regarding the generator idea, it is just that at present, an idea.I don't know what is available in terms of small modern gennies, but I have to imagine something like a Honda 125 or even a moped of some sort has something a lot more grunty than what was originally there.

Perversely, modern LED lights are probably enough with 60odd of uncle Joe's feeble watts - it's an option that has only recently become a viable possibility. I don't expect a whole lot of night driving on it, and as I'm writing this it's sounding as that might actually be a better option. That said, the original permanent magnet generator won't fit together with the engine shaft shock asorber so all bets are off at present.

Sorry I don't have a definitive answer right now, this is definitely "work in progress"

[RichardS]

That looks like the inner chain case off of a twin, well it looks like the one on my G12 having the two locating dowels and the recess at the tail end, which would account for the slight mismatch with the holes and angle I guess.

Having swapped out my 350 alternator engine for my 500 comp style motor, I've just done the same job mating up the ally chain case...
IMG_20230923_121733.jpg
As the case was from a single there was no issue with the three front fixings, but as there's no threaded boss on the 55 crankcase for the centre fixing, I put an extra hole in the case and added a small bolt.

I'd like a couple of shots of the foot rests you have. I assume you chopped the end off standard rests and welded the folding toothed ones on the end - roughtly what I ahve in mind, 'though I've not got parts yet so a bit of research is welcome

[Joker_Bones]

The foot pegs came off a G15CS. I wondered if they were home brew when I took them off, but I've seen them since and saw an identical pair on ebay advertised as such.
There is a discussion about comp foot pegs and some pics of these and a couple others in this thread...
viewtopic.php?t=30059

[Joker_Bones]

My lights are now running total loss off the battery... Like you say it's not a night rider and I'm going order up LED bulbs.

But... I keep coming back to the idea that if you could lock the drive cam and sprocket together, dispense with the spring, some smaller genny, a way of holding it all in place... Lol... Pipe dream!

[RichardS]

My lights are now running total loss off the battery... Like you say it's not a night rider and I'm going order up LED bulbs.

But... I keep coming back to the idea that if you could lock the drive cam and sprocket together, dispense with the spring, some smaller genny, a way of holding it all in place... Lol... Pipe dream!

Thanks for the foot-rest article link, I had seen it before at some point, but couldn't remember where.

Your generator scheme could work, but I am a little concerned about adding a big-ish weight on the end of a long-ish shaft and the potential dynamic and vibration effects that might have. Not so much from the 'smooth ride' perspective, but whether one might end up with a resonance that causes the whole lot to beat itself to death in one way or another. I'm probably being paranoid, but I've had two of the permanent magnet rotors fall apart with the outer magnets part becoming loose from the keyed centre sleeve.
In the extreme, you can lock the sprocket and cam with a welder - need to be a bit careful to maintain alignment, but it's one approach albeit a one-way street.

I was wondering about a slightly different approach of mounting the generator much as the original was and contriving the rotor to be mounted on some bearings also from the chaincase outer, then simply having a dog-coupling drive from the crankshaft. Probably make a nut with integral dogs, but I have no idea if there is space or if it is feasible, it's just a line of enquiry........

[ajsm18]

Thanks for posting such an interesting thread and all the pictures. It is very inspirational, even though it is far out of my own skill set!

[mdt-son]

As the case was from a single there was no issue with the three front fixings, but as there's no threaded boss on the 55 crankcase for the centre fixing, I put an extra hole in the case and added a small bolt.

Laser welding a boss at the crancase (enabling the centre bolt fixing) should produce very litte warpage. Alternatively, you could weld a triangular plate to your left handside rear engine plate, allowing a boss to be welded to the triangular plate. Drill and tap the boss when all is lined up.

Lessons learned by development of the G/N15CS is that 3 small screws at the front will not support the primary chaincase properly.

- Knut

[mdt-son]

I wondered as I was fitting the engine sprocket and shock absorber assembly if there was any way of dispensing with the shock absorber (there's cush rubbers in an AMC clutch) and fitting a rotor and stator.

Fitting a new drive shaft as per 1958 design (024132) appears to be the simplest solution. Anything else is hotch-potch. You may have to alter your D/S flywheel to suit.

- Knut

[mdt-son]

But... I keep coming back to the idea that if you could lock the drive cam and sprocket together, dispense with the spring, some smaller genny, a way of holding it all in place... Lol... Pipe dream!

I have no idea how to modify the cam shock absorber. What you could do is dispense with the magneto and fit a combined alternator and points plate in it's place. This will require a custom made housing of course. You could adapt an EI trigger plate and rotor as well. There are some neat DENSO alternators available which could be modified for your purpose. I have one in my Atlas Copco compressor. I can look up the output if you're interested.

- Knut

[Joker_Bones]

Nice ideas Knut...
Not a lot of laser welding happening in my shed these days, so a bolt and spacer to the engine plate will have to suffice and alternators will have to remain a pipe dream