72 CT70 Lifan Build

Discussion in 'Projects/Builds' started by wsurf4me, Feb 5, 2020.

  1. wsurf4me

    wsurf4me New Member

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    So I came across this on CL and couldn't pass it up, CT70 with Lifan motor, owner bought the parts but never put it together. From what I can see it's a 72 CT70HK1, the Lifan motor appears to be an older 125cc but I'm not 100% sure. Current plan is to put it together with the Lifan and have some fun. I will save all the original parts in case I want to do a restoration in the future. Been doing a lot of reading but any advice or guidance on the Lifan conversion would be appreciated. I've been looking for a guide but so far haven't found it. I can always wing it but like to see what others have done.

    20200202_183813.jpg 20200202_182850.jpg
     
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  3. cjpayne

    cjpayne Well-Known Member

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    That original paint looks savable.
     
  4. OLD CT

    OLD CT Well-Known Member

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    Time to buy a trailbuddy or webllc wire harness, that's a place to start. The bike should have the front end cleaned and rebuilt, oil tuned with some good updated rear shocks and a bigger bore exhaust.
    Shelf that ''puny'' carb also. It's too small for a 125cc.
     
  5. wsurf4me

    wsurf4me New Member

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    Yes the paint is overall pretty good, planning on breaking it down and polishing it up - should clean up just fine.
     
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  6. wsurf4me

    wsurf4me New Member

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    Thanks, yes I saw a couple of places have harnesses, sounds like the best way to go. I'm thinking about an aftermarket front end and rear shocks. Also have a carb with the 125 but no idea what size it is, I'll take a closer look. Any suggestions for the exhaust?
     
  7. airblazer

    airblazer Active Member

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    Trail Buddy makes the Thumper 2, which is a pretty nice one that should work with that motor if you’re interested in retaining a semi-stock look. But I just checked their site and it shows out of stock. It might be available elsewhere though...
     
  8. wsurf4me

    wsurf4me New Member

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    So I did tear down today, as usual a few surprises -

    20200208_190844.jpg
    All I can say is wtf?

    20200208_192303.jpg
    Pliers were inside the frame, sitting below the gas tank on the engine. Maybe used to crank that sheet metal screw into the engine.

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    Ready for sandblast

    20200208_192512.jpg
    Will finish breakdown tomorrow and give her a little shineup.
     
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  9. racerx

    racerx Administrator
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    Bad as that motor looks, from the outside, it's still an H-motor and worth holding onto. That brutalized intake bolt hole probably just needs a helicoil, or Timesert. The K0 muffler is a bit suspect but, if that's the original motor, you've snagged an amazingly complete...largely unmolested...HK1. I agree, the paint should cleanup pretty well. Use a mild abrasive and proceed slowly. It's very easy to remove lacquer and, since this was 2-stage (base/candy) it's also easy to change the color, i.e. create light spots. I'd start with carwash soap, followed by cleaner wax, in paste form. That may be all it takes, with some elbow grease. Detail clay may be helpful, if you have it. If more aggressive rubbing compound is needed, machine-compound containing a diminishing abrasive (used by hand) or swirl mark remover are your best bets. Old-fashioned/old-school rubbing compound will burn through lacquer like a propane torch through toilet paper.

    As for the front end upgrade you mentioned, this fork works better than you might think possible...with a fresh rebuild (cleanout + new seals) and "oil tuning"...better than the cheap Chinese inverted forks that seem to be on every "custom build" lately. The stock drum brakes do leave a bit to be desired, vs hydraulic disc. That said, properly adjusted, cleaned and wearing fresh shoes, they are quite adequate up to about 50-55mph. That's about as fast as this L125 can take you. Above 50mph, compression braking scrubs-off mph very effectively; a little bit of riding technique and you're fine.

    This engine really can't use more than a 20mm carburetor. 18mm is likely enough to keep it fed. If the supplied carb came with the engine, as part of a "kit", may as well give it a try...doesn't cost anything. If you do want to go bigger, I recommend a Mikuni VM20...you'll have to jet that for yourself, from scratch.
     
  10. wsurf4me

    wsurf4me New Member

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    So I've decided to rebuild the front forks, everything is apart and I'm in the process of cleaning up and reassembling. I found a little bit on how to take apart but can't find anything on how much fork oil and what viscosity, anyone out there have details?
     
  11. racerx

    racerx Administrator
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    Start with 3.5oz, using 15W fork oil. Look down inside the inner fork legs, when fully compressed (easy to do without springs in place); you want the fill level ~5-6" below the cap bolts. Fully extend the fork leg, then install the cap bolt and test the compression action. It should be reasonably stiff near full compressed height (bottomed-out). If you want stiffer fork action, add 5cc additional fork oil & retest. 3" below the caps is the practical limit; adding oil in 5cc increments makes it easy to keep track of the changes you make...once you get one side tuned, just add the same amount of oil to the second fork leg an you're done. BTW...if fork action still isn't firm enough for you, then it'd be time to drain & refill with 20W. Measure the amount of oil drained, it will be less than 100%, but that's really not important. What does matter is not overfilling the fork legs...that will deliver unpleasant results.
     
  12. wsurf4me

    wsurf4me New Member

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    Thanks racerx, got everything cleaned up and back together. Haven't tested them yet, still need to get the wheels cleaned up and back on along with new brakes. Hopefully be able to get to it next weekend.
     
  13. wsurf4me

    wsurf4me New Member

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    So I've been focused on getting the chassis and wheels cleaned up and put back together. Today I took a look at the Lifan engine and it looks like I'm missing or lost the CDI unit. Did a little searching online but as usual seems like I find more questions than answers. The engine is a 125cc Lifan manufactured in 2008, any suggestions on the proper CDI unit?
     
  14. racerx

    racerx Administrator
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    With the fork refill, you'll need to do some testing to get the best ride quality. It's easy, just takes a little time.

    As for your missing CDI, I'd contact T-bolt...to source a Lifan CDI module and figure out the pin positions in it. It might be plug & play. But, there've been a lot of different L125 flavors out there since 2004, when these motors became plentiful. Color-coding and wire routing may have changed. However, once you identify the pin positions in the CDI plug, by tracing the stator leads back their sources, you'll be able to figure out which lead corresponds to which connector pin, regardless of color-coding. And it's actually pretty simple: exciter/trigger, ground, switched ground, coil primary, secondary/HT coil.
     
  15. wsurf4me

    wsurf4me New Member

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    Thanks racerx, I tried T-bolt but no answer - I went ahead and sent an email. In the meantime I started doing more research and fell down the rabbit hole, learned some about cdi but also more questions. Going to take a closer look today, determine if I need ac or dc.
     
  16. wsurf4me

    wsurf4me New Member

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    We have a roller - new tires, bearings, seals, bead blasted and painted rims, rebuilt front forks, new rear shocks.
    20200411_180545.jpg
     
  17. racerx

    racerx Administrator
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    It's a magneto ignition, no battery required and no issue over ac vs dc; the pickup and primary coil connect directly to the CDI module. Those leads are simple to trace; the key is figuring out which of the 5 CDI module pins is the exciter (pickup) signal and which is the primary coil output. That leaves pins to ID: system ground, switched ground (kill switch) primary ignition output which goes the to secondary (HT) coil.


    Now...on the lighting/charging side, it's all ac. Best guess, this engine has a 5-pole radial array stator. Two of the coils feed the battery, through a rectifier; three coils feed the HL circuit, this is usually the yellow lead, which is "T"d...run to one terminal of the rec/rec AND the HL switch.
     
  18. wsurf4me

    wsurf4me New Member

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    T-bolt got back to me last night. Placed order for cdi and a few other things just now.
     
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  19. wsurf4me

    wsurf4me New Member

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    Well, finished it up this weekend. I had to do a little fab to get everything to fit around the motor - footpegs and engine guard needed custom brackets, also the old brake pedal wouldn't clear - welded up a new one. We will see how long the Lifan lasts, for now it's alot of fun just to blast around on.

    20200503_160241.jpg 20200503_160334.jpg
     
  20. wsurf4me

    wsurf4me New Member

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    Before
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    After
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  21. OLD CT

    OLD CT Well-Known Member

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    You are losing a lot of top end speed and good gear spacing with a 45 tooth rear sprocket. Must wheelie out even in 3rd gear!
    I suggest dropping 10 teeth on the rear sprocket...
     
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