Need Help Diagnosing Problem with Lifan 140cc

[Thescarceman]

Hey guys, new to the forum. I have a Lifan 140cc motor in a 1971 Honda CT70. The bike is a blast and has been running great until of course it just stopped running period.

I got it home, checked that it was getting gas, spark, good compression, checked the valves, went through the whole wiring harness, replaced the CDI, made sure the battery was charged and good. I checked the ohms on the 6 pole stator and was getting a reading of around 500 off the red and black wire and around 300 off the blue and white wire. I have absolutely no clue where to go next. When I kick it over it will fire for a few revolutions then stop and the pipe is definitely getting hot so I know it's firing. I just have no clue. Here is a video so you can here what it does. Does anyone have any ideas?

Really appreciate all your help and I've already been using the website a lot to answer some of my other questions.

[video=youtube;d027_GR3CTM]https://www.youtube.com/watch?v=d027_GR3CTM&feature=youtu.be[/video]

 

[Thescarceman]

So what do you think about this possibly being the pickup on the stator? I hooked my multimeter to the blue and white wire, put the other end to ground and rotated the motor until the tab passed the pickup. Not beep from the multimeter. I was checking the gap and it seems large. Does not adjust in anymore than it already is. To test if the pickup was working at all, I stuck a steel feeler gauge to the magnet and still no response, however if I run my feeler gauge quickly along the magnet on the pickup I will get a really quick beep.

I have a motorcycle salvage yard close to my house and i just saw another motor like mine that still has the pickup on it. Can i simply snip it off and solder it on to my wires? I know I will need to order a new stator, but do you think this will work as a temporary fix?

 

[my67xr]

Welcome to Minirider's,

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Both reading's from your stator show it has high resistance, i would be removing the flywheel and fit a new stator.
A replacement stator should be under $30 inc delivery off ebay etc (they are that price here)
eg; Magneto Stator Plate Lifan 140cc Engine Pitbike | eBay
And you will also need a flywheel puller to remove the flywheel off your engine, get a decent brand one like Motion Pro etc. it has an M27 x1mm l/h thread like this-
NEW Flywheel Puller 27mm Honda Yamaha Kawasaki Suzuki Magneto Stator Engine Tool | eBay


Cheer's, Craig

 

[Thescarceman]

Thanks for the reply Craig. I already have the flywheel puller and I just ordered the new stator. My options were shipping from China or shipping from the U.K. I order the one from the U.K. but on second thought I bet the shipping from China would be faster because of the USPS shipping agreements with China. Oh well. I think you're right about needing a new stator. Will update the post once the new one arrives and I get to try it again.

 

[my67xr]

I have just checked a 6 coil stator i have here.
With my meter set on 2000 Ohms, i get a reading of 240 Ohms for the pulse coil on the outer of the flywheel, across the blue w/white wire and the green wires from the stator
Across the black w/red wire and green wire's i get 500 Ohm's, so your source coil might still be ok?

Maybe take your multimeter to the bike wrecker's and check the reading on his pulse coil.
Most pit bike's read around 130 Ohms across the pulse coil which might not work with your bike,
so depending on what stator/pulse coil is in his, swapping that over to your's could get you out of trouble for the moment (if his read's around 240 Ohms)

You can take the pulse coil off the stator plate by undoing the 2x philip's head screw's
Check your's hasn't got and metal bit's stuck to it and causing a false reading
You can use a needle file and file the hole's out so you can adjust it closer to the flywheel pick up tab
To adjust it slide it close to the tab with a .1mm feeler gauge between the tab and pickup.

Dont forget to check all the electrical connection's for corrosion too, clean them up and use some tune up/bulb dielectric grease on them to prevent problem's in the future
Also make sure the green wire from the stator is screwed to a clean (bare metal) earth on the frame somewhere, same thing with the earth for the ignition coil dielectric grease on the bare metal here will stop it rusting