Planet Minis

resolaru

I have a 1971 Honda SL70. It's been in the family since new. The original Honda engine was shot, so we bought a 125cc Lifan engine. The only thing we can't figure out is how to wire this thing. Everything else is stock on the bike. We put a new 6 volt battery in it from the dealer.

I found a rectifier and wiring harness at dratv.com that supposedly makes the 12Volt Lifan work with everything else being 6 volt on the bike.

Do I need a CDI unit? Where does the CDI unit go - is this the stock one, or do I need a new 12v one for this? I'm assuming the Lifan has a built in stator. The Lifan engine has 2 separate wiring harnesses. From what we can figure out the one entire set is not needed at all, as it is just for shift/gear lights, which this bike does not have.

We've tried wiring this thing all different ways, but get no spark. Ignition is good, we believe, as we get lights when we turn it to ON position.

Any help is greatly appreciated, as we are at a loss. I spoke to the Honda dealer and they'd look at it, but would charge $60/hr and said it could take anywhere from 2hrs to 5... For 2hrs, it'd be worth it, but not for 5!

chuckklr04

Look here. It's not that hard.

CUSTOM & ENGINE SWAP PARTS

chipwich

You should use the CDI that came with the new motor. The rectifier is the little box that converts the AC output to DC. The one that probably came with your new motor outputs 12V, but to use your new 6v battery, old head and tail light, you will need a 6v rectifier. The page that chuckklr04 linked above has those.

chuckklr04

I havw the 12 to 6v rectifer if you want it.

HondaZrider

I just did the same engine swap and dratv's two harnesses made it a snap

I wish that the harnesses were around when I put a 125 in a z50 a while back...that was a real PITA!!!

What did your engine come with? typically they come with cdi, coil, carb and intake.

These are what you need:

ENGINE_SWAP_WIRING INSTALLING_A_CDI ENGINE_IN_POINTS TYPE_BIKE (SUB_W_1)

12V_or_6V CT70 REGULATOR RECTIFIER_PIGTAIL CLICK FOR_INSTRUCTIONS (SUB_W_12/12/6/6)

Good luck!

Will

nickypoo

heres my old 70 with a lifan 125

resolaru

Thanks for the replies. I should have stated that I already have the rectifier and pigtail wiring - I purchased it from the dratv.com website. It helped some, but still not enough to figure out where the wires from the Lifan engine go. I have the correct rectifier (from dratv that converts from 12v to 6) and have it wired correctly. The Lifan engine came with everything - the carb, intake, CDI (I think).

I need help with the cdi wiring and the wiring from the Lifan engine. I'm attaching a crude picture of the wiring coming from the Lifan engine. From what I can figure out, I don't need the block of wires on the left with the green connector. I think it's just shift indicator lights, which this bike does not have. Is that correct? The wires on the right are what I don't know goes where. Is the CDI unit a small black plastic box with a male 5 pin wiring connector? If so, where does that get wired to?

Again, I appreciate the help.

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chuckklr04

Where do you live? Maybe a fellow member can drop by and fix it.

chipwich

I'm no expert, but you are right about the gear indicator lights. Did you buy the rectifier pigtail, or the harness that attaches your stock harness to a new CDI type ignition?

resolaru

I have the rectifier pigtail. I didn't purchase the other wiring harness on dratv yet. Is that all I need? I was leary, because every time I bought something from dratv, I was told I needed yet another item from them... I have contacted someone at dratv via email a few times and although they seem willing to help, they seem very vague and not sure what I need either.

I live in the Buffalo, NY area. The bike, however is about an hour north of me at my father's house (1/2 way between N. Falls & Rochester). I can get it to my house if I need to. My father & I are both very mechanical, but when it comes to wiring a bike, we're just in the dark. I think in my dad's younger days, he would've been able to wire it...

cdoublejj

ehh, they still selling those lifans with those dinky carbs, try one of these Ahp Minis
you won't need a restrictor plate to mount your carb any more, need to put myl ifan back together.

jkg2003

resolaru did u figure it out, I am curious because I am about to purchase the same engine and put it in a ct70

resolaru

jkg2003 - not yet. I'm heading out to my dad's house tomorrow and we will look at it again. If I get it to work, I'll let you know. This picture of this wiring harness looks like it is the missing piece to the puzzle... we may have to order that as well (see attached pic).

Btw, when you do buy a Lifan engine, make sure the seller includes everything that goes with it (carb, intake, etc). The first one I bought didn't include all that stuff...their ads can be misleading. Also, for my SL70, we had to grind down the gear on the engine, as the teeth are much wider than the stock chain. We put it on a lathe and slowly ground off the teeth on each side until we got it to the right width.

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jkg2003

ya, you will need a cdi if you havent already gotten one, maybe that is why you are getting no spark, and if you have gotten one, I dont know, and I have already gotten everything that I need on the way, but thats funny how you mention the chain because the stock chain is a 420 and some of the engine are 428 and some are 420, I had already thought about that. I spent all day talking to Dratv via email and finally got what I needed so all I need to do now is buy the engine.

cdoublejj

it should run with out a harness, unless they didn't include the mini harness that comes with it for the cdi.

resolaru

I ended up getting that wiring harness from dratv & wired it earlier today. All the diagrams seem to make sense and match up with what I have. I believe i have everything wired correctly, but still no spark. I don't know what to troubleshoot as to what could be wrong. It could be a myriad of things... it's possible I have something wired wrong. Is it possible the on/off key switch on the bike is bad (although switching it turns the rear tail light on, so I think it's working ok). Is it possible the coil is bad? Is there certain troubleshooting steps I can do to figure out what's wrong?

I'm very frustrated with this thing - if this bike wasn't sentimental (it's very sentimental - I have a picture of it new with me at 2 yrs old standing next to it), I'd ditch the darn thing! I appreciate the help you guys have given me, but I'm just about at the end of my rope here. I keep asking everyone I come in contact with in my area if they know how to wire this thing, but nobody has a clue.

FastMC

You never mentioned a new coil...Did you get a CDI type coil or are you still using the original coil ?

jkg2003

I finally bit the bullet and got the engine and mine wired up just fine and cranked second kick, I also never heard you mention the cdi, like I mentioned earlier you will need that and if you are using the ori then it wont work because the ori is a 6v and you will need a new 12v cdi coil

resolaru

No, I didn't get a new coil. I thought the 12v to 6v rectifier I got from dratv handled all conversions. Here's what I have:

-Honda SL70 (1971) - all stock except engine
-125cc Lifan engine
-CDI that came with Lifan (small black rectangle device with male 5 pin plug on end) (I'm assuming this is the CDI)
-12v to 6v rectifier with pigtail wiring (from dratv)
-Wiring harness (from dratv) to connect engine, coil, etc (as HondaZrider listed)

Ok, so you're saying I can't use the stock coil? I need a 12v one? I guess that makes sense. If this is true, where do I get one for what I need? Does it come with wiring instructions? Maybe this is finally the missing link I need!?! I've never seen anywhere that I would need to change this.

Btw, how do I know if I have the right CDI? The item described above is what I have. I'm assuming this is the CDI. It came with the engine, so I'm assuming it's the right one.

Again, I appreciate all of your help.

jkg2003

this is what you need, it is a cdi coil and it replaces the stock coil thats on the bike and the installation instructions are on dratv website