More CT70 love here… After reading some about a friends scooter racing adventures got my minibikes back into my mind. The fact I am broke and could pretty much do some parts bin work helped too. After some more reading I realized that I do need a battery for the 70 to run proper, and many hours of looking at the wiring diagram I sorted out a new one. A lot of the work was undoing the work I did a few years ago stripping the harness. I wired the lights back in, less the turn signals, planning on platting it after I go back to NH next time. I’ll get the necessary paperwork from my dad and can have a silly plated CT70 just because I can. Overall everything in this project took way longer than it will to read, or to be honest longer than it really should have. To be fair I have been bleeding from the brain trying to keep up with my chem homework so it all works out. Besides this is for fun, or something like that, or so I keep telling, myself. Anyways back to the fun…
The broken OEMish set-up.
The years were not kind...
After an hour or so of looking at the wiring diagram I realized I had switchgear that wasn’t knackered that would work. Since I had stripped the OEM stuff off of my CB360 I recycled that onto the mighty 70. This let me play with the multimeter some to ensure I knew what all the wires did. Not surprising for 1970’s Honda parts the casting were almost identical, I was even able to swap the throttle tube right over from the 70 into the 360 unit. Besides having more switches to work off of I also had a brake assembly that would accommodate a brake light sensor. Double plus awesome there. Anyways after hours and many revisions I worked up a new working wiring harness diagram. Besides deleting the turn signals I also eliminated the keyed ignition. I do not have a good one to use, and even plated doubt I would really take this bike around town. Making a wiring diagram was the easy part, then I had to draw a new one showing where the wires would go and what I could put into shrinkwrap to run from one end of the bike to another. Another hurdle was making a battery box, since the OEM is long since gone.
The "new" switch gear circa 1974.
After more than a few tries to weld 20ga metal with my welder (I am sure my welder can do it, I just can not) I moved to 16ga. Last minute after some bad measuring I changed how it was going to be mounted I was able to make a workable box. I also found that my sheet metal brake that Rock supplied as payment for work on his former KZ400 would handle 16ga. Sorta wish I knew that when I was working on that KZ650 battery box a few weeks ago. Anyways some paint and plenty of drying time the battery box was good to go.
Layout and bending...
Ready for paint.
Final test fitting.
Since no one has bothered to make a sealed battery for 6v bikes I stole the idea to use a security light battery from one of the Honda minibike part suppliers. Damn near the same specs as the factory Honda battery for less coin and I can mount it sideways.
Now was the time for running wiring and checking the wiring many times too many with the multimeter. I found out the shrink wrap I bought was the wrong size, but pressed on. After more than a week messing with this when I had time I wanted to hear her run. There were some more “angry moments” when I mounted the tank and messed up some of the wiring. After that I was able to finally fuel her up and see if this whole project was for nothing…
She fired! The carb is still grossly out of tune, but the battery did make a HUGE difference. After minimal messing with the carb I was able to start the bike using my hand on the kicker first try, on a cold motor. I know this is a small motor and hand kicking it isn’t that hard, but I was impressed. I chalk this up for a victory none the less. Still have a bunch of tuning to do, but things are looking good, this makes me happy. There is also a good chance I will redo the wiring soon so I can shrinkwrap the wiring running the length of the bike, but modifying a running and laid harness that is proven is so much easier than doing it from diagrams I made.
Sometimes it is the small things, not just that it is a small bike, but a project that doesn’t matter. Things like the battery box were an engineering exercise for future projects that I know are going to come my way. I know this isn’t the only bike I will have to rewire, and doing things correct seem to mean more to me these days. I have the time, I am going to keep the bike, why keep doing it over and over again, when once right and that will be it. Other than the tuning I have other things in mind for this project. I have a café seat for a small bore bike that might make its way onto this bike. The bars have been bent and welded too many times, but I have a few extra sets of Husky bar clamps that should work and allow me to use any minibike bar. The exhaust will finish getting wrapped, these will happen. If nothing else small low cost victories can make an otherwise ego hurting world of college classes and weak job market bearable.
Next project?
