Please help, The motor will not shut off.

CoastsideXS650

CoastsideXS650

Princeton Motor Works
Messages
450
Reaction score
44
Points
28
Location
San Francisco, CA
I have a problem with my 1981 Heritage Special custom. Just finished building the whole thing and wiring it up but I am having trouble killing the motor.

I have a new ignition switch and new wires with solid connections. Using stock coil, ignition unit, and reg/rectifier. Bare bones wiring with just a headlight, taillight, and license plate light.

When the motor is running and I turn the key to kill the bike it wont shut off. Then I removed the main fuse and it still ran. I even went so far as to remove the battery leads and believe it or not it still kept running for another min after that (although not so well).

The only way I have been able to shut off the motor is to back out the idle screw on the carb or just let out the clutch at a stop with the brakes on.

Im really not to sure whats going on here and was wondering if anyone else had a similar problem.
 
The thing that usually shuts it off is no power to the coil. Make your wiring so that everything comes downstream from the ignition switch. Then when you turn the switch off, no power goes to the coil.
 
I had an odd problem like this with a Honda 500/4 i wired. It would stay running with the key off....Fuse out to the coil.....The minute i unhooked the stator. It would quit. OR, if the headlight was on it would shut off like it's supposed to when you used the key.. but no headlight on....the damn thing would stay running. I have built a ton of harnesses and this is the only bike this strange problem has happened on. Never did figure it out. It ran great, charged fine. I am an electrician and that thing still boggles my mind. :laugh:
 
I have the whole bike wired so that no power bypasses the ignition switch, even the power supply to the coil. The only thing I can think of that might be happening is that there is a charge still going through the bike even after I disconnect the battery completely and because the motor is still kicking over it forces gas and air through and still fires.

How can the coil continue to put out spark even after the battery is disconnected completely?
 
Chopper diagram for an '81. This is what I have. Might want to cross-reference.
 

Attachments

  • 650wiringchoppervh0.jpg
    650wiringchoppervh0.jpg
    48.2 KB · Views: 122
Yeah, sounds like your rectifier output is on the wrong side of the key.

A kill switch which opens the coil circuit is goodprotectionfor situations like that.

Posted via Mobile
 
This isn't his problem, but anybody remember those cars in the 70s that wouldn't turn off...
...
...
 
Oh, dieseling? Heard ofit,experienced it once. Was it too rich or too lean a mix that causedit? I should know, but can't think at the moment..

Posted via Mobile
 
I havent double checked my wiring yet but Im almost positive that I have it wired up correctly.

The dieseling might be the problem as this bike had not run in 15 years and the carbs were full of gas all that time. I rebuilt em and cleaned them several times and installed new jets.

The bike starts really rough and I had to use starter fluid initially to get it going. But the carbs are leaking fuel and not synched or probable properly adjusted for anything.

Could this be a possible reason for the motor firing without a spark?
 
After looking up Dieseling on Wikipedia it gave me these 3 reasons why it could occur. Anyone thinking that this is along the right thread with the carb issues?

Also the idle speed of the carb was way off and all over the place during a test ride that lasted 3 blocks before an electrical short. But that electrical short killed the motor instantly. So Im still stumped.

- A carburetor that does not close entirely can contribute to running once the engine is off, since the extra fuel and oxygen mixture can combust easily in the warm piston chamber. Similarly, hot vaporized oil gases from the engine crankcase can provide ample fuel for dieseling.

- Incorrect timing.
An engine that runs too hot or too lean may produce an environment conducive to allowing unspent fuel to combust.

- An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running.
 
I mentioned dieseling only because it brought it to mind. It is not your problem. The problem with your bike is what they're saying it is.

But if it was, the way we would turn those cars off (if we had standard shift) was put it in first, hold the brake, and slowly let out the clutch. LOL If you had automatic you'd go on in the house and it would sneeze and cough for five minutes.
 
it wasnt dieseling for a minute. it was running and had spark. dieseling only lasts for a couple seconds after you shut it off.
 
It is real easy to mix up the red and brown wires coming off the rectifier. the red wire has to be hooked directly to the battery, NOT the ignition switch or else it will stay running like that.
 
No, some kind of Mercury if I remember. BTW, I'm agreeing with you - his problem is not dieseling.
 
James I think you may be right about the wire. I tried to hook everything up to the switched lead.

I need to get to my shop and take a look at my wiring.

One more thing though, does anyone have any thoughts on adding a kill switch? I figured I would just kill it with the ignition but maybe a kill switch might be a good idea?
Any input would me appreciated.
 
Yes, a kill switch is a must. You can run the headlight or work on the lights without haveing the coil/ ignition getting overheated.
 

Similar threads

Mannyroad
URGENT HELP to source electric ignition for rephased motor
2
Replies
20
Views
886
Mannyroad
Mannyroad
DogBunny
cracked carburetor -- thoughts?
Replies
18
Views
644
DogBunny
DogBunny
I
Starter motor condition question?
2
Replies
34
Views
1K
jetmechmarty
jetmechmarty
Wilsonsk
TCI pickup coil to GN250 igniter wiring diagram, 1976 XS650C
Replies
14
Views
1K
Jim
Jim
C
Wiring Overhaul
Replies
2
Views
403
jpdevol
jpdevol
Back
Top