Honda SL70/C70 mashup

1337gallagher

1337gallagher

New Member
Good morning,
I recently purchased this project bike for $100 and am trying to get it back together and running enough to use as a pit bike. the previous owner never invested any time in getting it fixed and it is missing many parts. however, the frame has been stretched 2" and it has an electric start 1980 honda c70 engine. The engine is a semi-auto transmission and the flywheel/points setup is different from what most of the youtube bikes has. I have ordered a wiring harness, ignition switch, and regulator. I have a C70 service manual for it also. I understand this will be a bit of work to get up and running. Any advice on the wiring and spark setup?

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It’s hard to tell but I don’t think that’s an sl70 frame,,it’s definitely a Yamaha gas tank..the way the sprocket is bolted on is not an sl70 rear hub as they have a clip on rear sprocket,,not sl70 rear shocks either,,,good luck with that one…lol
 
If you want to see if it has spark right now, you can run a jumper wire from the black/white wire coming out of the stator to the black/white wire on the ignition coil, basically bypassing the rest of the electrical system, as shown below in yellow.

1980-81 C70 schematic - 6V-1.jpg
 
Interesting, I honestly know very little about these small bikes. It's definitely been modified, but it is a pretty clean slate. I'll install the bare minimum wiring to get it to run and work from there I guess. My spark plug will be here tomorrow. Wish me luck.
 
I installed a new 6v starter coil and ran a wire as highlighted above. I have no spark. I sanded the contact that I think is the condensor (pictured above) and will try to trouble shoot deeper in the engine tomorrow. I have no idea what the brown/red wire that is near the condensor goes to, it was disconnected under the cover.
 
Also, because I am having to re-wire this from scratch and have no components other than the motor, is there a preferred way to rewire this without an original harness? Do I just go wire by wire and bundle them when I'm done? I don't plan on putting a horn, turn signals, or dash in this. I really appreciate the wiring diagram dirtbkr188 posted. The diagrams in my manual don't have a starter model illustrated or don't show a condensor.
 
this is the barebones version of the schematic after I ran it through some high powered ms paint.
 

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Because this engine is missing the gears, chain, and guides for electric start, I will be selling it off for parts. I am putting a 125 chineese pit bike motor in this frankenstein and calling it a day. The motor I selected is an auto transmission, electric start which will be perfect for my wife or for bombing around campsites. This bike was just too incomplete/frankensteined to be pulled back to a rust-ored condition. I stripped the tank and welded up a big hole I found in it. I'll try to post some pictures as things progress.
 
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