Planet Minis

FastMC

I thought this might be usefull for anyone building a 12V CT70 or converting a 6V to 12V. I recently built a bike from scratch so I didnt have any wiring harness. The motor used is a YX140 with lighting coil (2 outputs). I started with a Trailbikes wiring harness for the K3 to 76 models since it's setup for turn signals. These wire harnesses from TB are really nice for the money...$30 is a bargain and is 1/4 the price of an OEM 12V harness. I also used one of the CDI pigtails he sells to use a Honda style CDI box. I used a spare OEM Honda CDI from my parts bin.
The harness doesnt have any real ground and relies on the grounding of the ignition switch, so that was first on the list.
A few wires will have to be added to bring the AC from the stator to the 12V regulator/rectifier and the CDI source coil and pickup.
The only ignition wire in the 6V harness is the black wire that goes from the points to the coil and also goes to the ignition switch to kill the motor, it also leads up into the headlight where you can connect another kill switch...I used that black wire as my kill wire, connecting it to the Blk/Wht wire of the CDI system.
I sliced open the harness from the motor back to the battery, and to the taillight connectors to add my new wires. You could add them externally but I wanted a nice clean looking harness when I was done.
The 6V harness has a blue wire coming from the battery negative terminal that leads to the ignition switch and turns green along the way. I soldered in my ground wire to this and added a ground lug that bolts to the frame in the rear of the bike and an extra for the taillight housing. I also ran the ground wire down to the motor connection. On the 6V bikes all the rear lighting relies on a frame ground which is not that reliable so I continued my ground so that all the rear lighting has a good ground wire to connect to.
Next was the charging system inputs....The 6V system has 2 wires. Yellow from the motor goes directly to the ignition switch then on to the lighting. I kept this wire and tapped off it to go back to the new reg/rect....The other green wire originally went to the silicon rectifier in the old system. You can use that for your other AC wire if you want. I chose to remove it and replace it with a white wire so it would match the new AC output from the motor. This also goes up to the reg/rect. You will have to add another ground wire to the reg/rect connection. The red/wht wire in the harness will remain as it is and will be the fourth wire going to the reg/rect.
Last modification to the harness is to add the two CDI wires. Blk/red from the source coil and Blu/wht from the pickup coil. I mounted the CDI box down in the frame next to the ignition coil so these wires didnt need to be very long and also made the connections from the CDI to ignition coil very short. The Trailbikes CDI pigtail was used to tap into the ignition system with all connections soldered and shrink tubed for reliability.
All that's left is to add a 4 pin connector to connect the new 12V reg/rect. The harness had 2 of them which were removed for the conversion so one will be used for this.
No modifications to the harness were needed from the motor forward to the ignition switch/headlight area and the brake light/flasher relay pigtail is unchanged.
This motor did not have a neutral switch so the Grn/red wire isnt used. Some of the Chinese motors have them and it's a simple hookup.

Again, this is a great wire harness for the money and with a little labor and a few connectors it should make for a very reliable electrical system.
This can also apply if you're keeping your CT 6V. The only difference being a 6V reg/rect and battery.
To be continued...
Jim



New ground lugs and lighting grounds.






Wires added for CDI inputs and TB pigtail.





Finished product.

FastMC

It's tight down there...Not a lot of room for your hands to work !!!

firepower354

Nice work, sir

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gbunner

I have a 1971 CL70 that I am considering upgrading to 12 volt. Is my bike the same as what you just did? I could follow your instructions to duplicate the harness, but if my bike is different I would get confused. Would you consider building me a harness like that?

Thanks, Gary

topr

I will have this same project soon, this will come in handy...muchos grassy ass

cdoublejj

can you please make this a sticky imagine homw many threads could be solved before they are posted.

muxster

Lets See that same wiring with 1 yellow wire coming from a Lifan 150cc !

Nice clean work you do!

Blackwoodz

Nice job.......sticky this...

slimbo

great idea

Z

Threads don't get stickys. They get linked to the master thread on tech resources here.

http://www.planetminis.com/f14/z50-c...tml#post985422

This one is added.

FastMC

Got this buttoned up and running last night. Using a reg/rect from a late model CT. Charging voltage at around 5k is 14.5 volts. Lights and signals work perfect. Headlight dims slightly at idle which is what I expected. Will post pics of the completed bike in a couple days.

NHCT70

Any pics yet?

Motarded

????

FastMC

What's the ?????