125 Wombat runs great then headlight on runs bad

[MTRob]

My 125 Wombat 94A runs great and strong, then one night I took it out with the headlights on and road for about 2 hours, then all of a sudden it started to miss and run like poo. I turned the headlight off and it ran great again. Turned the light back on and it started missing again. When I rebuilt it I replaced all the stator parts. Seems to me it is not getting enough spark when lights on. Battery is also new. Tell me what you think of that.
MTROB

[Bullfrog]

Check the main switch for proper operation and making all the proper connections with virtually ZERO resistance in the switch itself.

Ed

[Dale]

I had a 94 that would run "okay" without the lights and then would not make it around the block with the lights on. I found that the points were worn way down on the part that rides on the cam. I replaced the points and condenser at the same time and it ran great after that. Points or condenser? I will never know...

MTRob, Could it be that your new condenser is defective? Or perhaps damaged by heat when installed?

Dale

[TrophyHunter]

For the new, and electrically illiterate, is the "main" switch the key turned all the way or is it the switch on the headlight bucket. I actually just saw the switch on the bucket and read the manual on it but not sure I fully grasped everything. Bucket switch goes from running on mag to battery? Been a week or so since I read it.

[Bullfrog]

The "main switch" is the key operated switch.

Ed

[TrophyHunter]

Thank you.

[MTRob]

I replaced everything in the stator, coils, points, condenser when I rebuilt it and it only starts acting strange after about 1 to 2 hours of riding with the headlight on. Turn the lights off runs fine. Did an experiment and rode it with the headlight on till it started acting up 1.5 hours. Turned them off
and ran great. Parked it for a couple of hours jumped on it and turned the lights on and it ran great for about 1.5 hours till it ran like -hit. Turned them off and ran great. Figure this one out. The rectifier and current limiter are new.
MTRob

[BrianZ]

The ignition circuit on this bike is separate from the rest of the electrical components, so it should in no way be impacted by the lighting circuit. Since it is, you need to start looking for shorts in the wiring or other components. You mentioned that you had replaced all the stator components. Are you absolutely certain all your wiring is correct? Double check it to make sure. All the solder joints need to be clean and shiny with no "cold" solder joints.

Assuming the stator is correct, I would look at the key switch next. The only way the key switch effects the ignition circuit is to short it to ground to shut off the engine. I would like to say disconnect the key switch to see if the problem goes away, but then you will have no way of shutting off the engine. This could have "consequences" if the throttle sticks for any reason. To eliminate the key switch as the source you could try wiring a kill switch in its place. To do this disconnect the key switch and connect a kill switch between the connector (where the key switch was connected) black wire and blue wire. Make sure the kill switch works, and then try the bike again to see if the problem is resolved.


Brian

[MTRob]

Brian
Did what you said thanks. It didn't make any different still started acting up after about 1.5 hours. Checked all the wiring since I made the wiring harness. I new what to look for. I think Something is heating up and causes it to freak out. Any Ideas what might be getting hot and not working right.
Come on Guys and Gals what do you think? ( Ed, Taber, Richard, Paul anybody) Great thing is I am getting to ride it alot.
Thanks loads
MTRob

[taber hodaka]

Rob I would suggest riding up hill so you can always coast back. Check spark when it Quits. Also check the flow of gas. Rob what plug are you using. Do you have good compression when it quits. How long does it have to cool before it starts and after it starts how long will it run.-------- Clarence

[MTRob]

Taber
It doesn't quit running just runs like its missing. Changed plugs makes no different. Have filter on carb looks clean no problem there.
Using NGK B8HS plug. I will figure this out.
Thanks
MTRob

[BrianZ]

Since the problem only occurs when the light is on, and the ignition circuit operates independent of the lighting circuit, you must have a short somewhere between the ignition circuit and lighting circuit. You mentioned that you had made your own wiring harness so I would look there. I'm not trying to be insulting, it's just that even the best mechanics will, and do, make mistakes. Disconnect all the wiring except the ignition circuit. All you should have is the two blue and black wires between the stator and the ignition coil. That's all the engine needs to run. With just these two wires remaining your problem should go away. If the misfire is now gone, you've isolated the problem to the lighting circuit. Now you need to recheck all your wiring, particularly at the key switch.

If it still misfires after it warms up then the headlight was just a coincidence and you need to look at the ignition circuit. Check those black and blue wires going to the coil. They have vinyl insulation that cracks with age. Since they run inside vinyl sleeving they are held close together and the cracked insulation can cause intermittent shorting. I have also seen ignition coils breakdown once they get warm. And as always, a bad condensor could cause your problem. Condensors dry out with age, so whether they are just old, or new old stock, there could still be a problem.

Brian

[Bullfrog]

Like Brian, I'm sure that differences in engine operation when the lights are "ON" or "OFF" must relate to a wiring fault, connector fault or malfunction in the main switch. ( and I have been hesitant to say that I'm pretty sure Dale "fixed" such a fault without knowing it when he replaced his points and condenser )

Ed

[Dale]

Ed, No need to be hesitant! That would very likely explain my situation. I did indeed clean up everything under the magneto while I was in there to change out out points and condenser. I certainly had an issue with the lights on and it was fine afterwards. I am just sorry that I was not able to isolate the exact cause...
Dale

[MTRob]

Thanks Guys. I figured it out. Since the wiring harness is new, it has new rubber ends on the wires found a Blue one not quite plugged in all the way.
Pushed the two together and works great now.
Always something small to mind boggle you.
MTRob

[Bullfrog]

Hot Dang! Dontchajustluvit when all this digital, long distance, head scratching and collaborating ends up in solution to a problem?(!)

Ed

[MTRob]

Ed
Amen!