Here's a new one- motor won't STOP!

[Nashville Kat]

I've put another NEW kill switch throttle body on- before that I cleaned all the contacts, then I jumped another ground wire between the two motor mounts and hooked up to that, I've cleaned the black wire contact inside the magneto cover, and today spray cleaned the whole thing again. The white wire appears sodered onto the magneto and not compromised there.

It will kill until it gets warmed up, but then it the motor won't stop until I pull the plug wire, and I hate doing that. Any ideas?

Is trhere a better place to ground? The more I've worked on it, and with a second new throttle, it seems somehow internal. Is there some way the magneto can fail in this manner. 50cc China Girl, running fine otherwise.

I kill the motor ALL THE TIME when I ride when I know I'm coming to a stop...

I don't like this emoticon, but this is how I feel:

 

[maurtis]

Can you kill it with the choke? I do not even have a kill switch any more so I choke to kill the motor.

 

[porkchop]

apply the brakes let clutch out..that will kill motor

 

[Nashville Kat]

I think popping the clutch with the brake on is hard on the clutch and the rest of the motor.

Maybe choking will kill it and be better than pulling the plug wire- but it's not an acceptable solution- I like to coast and be shut off in populated areas.

Has anyone else had any trouble like this? It's not the button- it's doubtful it's the ground, after all I've tried to get that real good and in contact- It worked for three years before that- my other build hasn't had any such problems in 3 1/2 years-

Maybe I'll switch the magneto, but hate to spend another 15 dollars or something.

What about how the magneto is attached. Is that attached AND grounded somehow as well? Anyone?

 

[biknut]

That is a crazy problem for sure. WTH lol. All I can say is anything that can't happen, can happen.

I don't know if you're wireing the same as me. This is how I do it.

The way I think about it is, the kill switch doesn't actually have anything to do with ground. What it does is, connect the black, and the blue wires together.

I do realize the black wire is grounded, but the reason I look at it the way I do is because that's the way I wire it. I have the 3 black wires hooked together, and the 3 blue wires hooked together.

So we have 3 black wires hooked together, one from the magneto, one from the CDI, and one from the kill switch. Then we have 3 blue wires hooked together, one from magneto, one from the CDI, and one from the kill switch. That's it.

If yours is wired that way, and you've replaced the kill switch once, and it still does it, it has to be 2 bad kill switches.

Some of the kill switches I've got have a black wire and a green wire instead of a blue one, but that doesn't change the way I hook it up.

 

[biknut]

Obviously there's nothing wrong with your black wire magneto ground, or your bike wouldn't run at all.

 

[2door]

To test is simple:
With the engine running connect the blue and black wires. If the engine dies, the problem is the kill switch or the wires from it.
The kill switch (button) is just a set of contacts that connect the two wires from it. There's nothing mysterious about the kill switch. With their history of failure I wouldn't be surprised at all if you had two bad switches in a row.

What I've found is the sliding contact is binding and not being pressed outward by the spring under it. A little work with an Exacto knife, #11 blade will clean up the track that the contact moves in allowing the spring to push it against the stationary contacts, the ones the wires are soldered to. Lubricate the parts with a silicone based grease. Do Not use WD-40 or some electrical contact cleaner/lube. They can attack the plastic and weld the parts together.

Tom

 

[CroMagnum]

The white wire appears sodered onto the magneto and not compromised there.

Are you trying to kill the engine by grounding the white wire? If so, that's your problem. Ignore the white wire and follow the advice from biknut and 2door and connect the kill button between the black and blue wires.

 

[nightcruiser]

I would also say it probably has to be a couple bad kill switches, reason being, the blue and black wires must be connected to the magneto properly in order for the motor to run. The kill switch should be wired to short these two wires together, and that will take out the ignition. It's really not all that complicated, I can't see any room for crazy voodoo here. The kill switch is a momentary on switch that simply connects two wires together when activated.
That said, this year I have actually done away with my kill switch, mainly because I run a dirt bike throttle that doesn't have any switches on it. I had rigged up my own kill switch last year, simple radio shack momentary on push button jammed into some copper tube for mounting, which worked fine. When I rebuilt the bike over the winter I eliminated the front dérailleur (mountain bike) because I never use it, since I had the integrated levers for the front dérailleur built into my brake lever I figured I might as well use it for my CNS "choke" lever. This simple modification I love for several reasons. #1, I was able to eliminate that cheesy lever that came with the carb, #2, the shifter lever is easy for me to push in with my thumb whenever I need to richen up my mixture. When I start the bike and ride it cold I only need to choke (enrich) for a brief moment so I just hold the lever in (don't push it far enough to lock on) then when I let go the choke snaps back to OFF automatically. SWEET! Finally, I realized when I choke the warm motor she dies, so I just use the choke lever to kill the motor now and have eliminated the kill switch. The choke actually works better to kill the motor, with the kill switch if you don't hold it down long enough the motor will spring back to life but the choke kills off the motor really quickly.
I know lots of people swear off the CNS carb, but I love mine and this convenient choke/kill setup is one of the reasons. I also think the CNS would be a great carb for people who ride at different altitudes. I read someone talking about putting a strand of wire in their jet when they are on a mountain to lean her out, with the CNS you could tune the main jet to run well on the mountain, then run with the enrichment jet open when you are closer to sea level. Since the CNS has 3 jets (idle jet, main jet, enrichment jet) and the enrichment jet is operated by a cable pulled lever the carb could be tuned for dual altitudes using the enrichment jet. That would be a whole lot easier than installing a strand of wire in your main jet...
Sorry to digress into talk about the CNS carb here, didn't intend to change the topic.... but if you are frustrated with cheap kill switches failing try using either a radio shack momentary push button switch or the choke instead....

 

[Nashville Kat]

I took out all the screws one by one of the magneto and cleaned them all off and flushed the threaded cavities, and scraped the points of contact where they tighten- that seems to have made a large difference- but still maaybe just a bit sluggish to kill as it warms up.

I agree about the wire- although both the white and blue wires appear connected to the magneto in the same fashion at different points- i followed some instructions from somewhere and hooked the killl to the white wire and also to the motor mount ground. It makes more sense to kill the blue coil wire with a ground tho and won't rely on the magneto connections- I may have helped the performance a bit there- the seal was blowing pressure out until I gasket sealed it, so everything got a bit oily I think.

I'm gonna wire it to the blue wire tho. I first thought about trying to toggle directly between the coil wires, but it would have to be a switch that set to on/off. Yes- the best way would be to ground to the blue wire in a three prong connection- I had three connected together at one point years ago I recall- then somehow started using this other connect-

I haven't even looked at the other build to see how it is- never had any probs before.

 

[2door]

What do you mean by "the seal was blowing pressure out" ? If you mean the crankshaft seal behind the magneto rotor, the only way to repair it is to replace it. Gasket sealer will not work.

Tom

 

[maniac57]

Have you considered a plug that is too hot? If it only stays running after it's warmed up, it might be due to the plug tip staying hot enough to cause ignition? (I know it sounds screwy. but I have seen it happen once before)

 

[biknut]

Have you considered a plug that is too hot? If it only stays running after it's warmed up, it might be due to the plug tip staying hot enough to cause ignition? (I know it sounds screwy. but I have seen it happen once before)

Good guess, but he said it dies when he pulls the plug wire.

 

[Nashville Kat]

YES! Did a 3 way connection to the blue wire between the coil and the motor- kills it off really fast and solid now- doesn't have to work through those magneto bolts to go to ground on the white wire- kills it both at that end and cuts off motor coil.

The spark plug could have been a contributing factor as mentioned above I guess- but inconclusive there. Still, I did switch it to the NGK 6 -I think it is- from Sick Bikes last winter, not too long before it started. Runs good. Also recently put a 66 Speed carb on the 50cc motor- this thing DOES run well otherwise, so maybe there was just more to "kill".

Problem Solved. Thanks for contributing!