blown fuse ingnition coil hot as hell

[jave101]

hey guys
after playing around with my gs400 todays i was putting the tank on after fiddling with the carbs with no luck. I saw the neutral light turn off, checked it was still in neutral, took the tank off and found that the right hand ingnition coil was damn hot, I think I've got a short somewhere as I blew the 15amp main fuse.
is there any test you can think of to try and isolate the short. the coils are brand new and hard soldered with heat shrink over the joins.

replace fuse and swap coils to see of the right hand side coil is the problem? or is there a multimeter test i can run?

thanks for the help

[jave101]

Ok so checked over the wires I might have nicked putting the tank on, they all seem fine.
I was reading my wiring diagram and this is what I've come up with, correct me if I'm wrong.

Positive goes to ignition switch then to kill switch then primary ignition coil winding, then breaker point and if the breaker point is closed it earths out.
The only resistance I can see in that circuit is the primary coil so that is probably why it is heating up.

Only when the breaker point it closed will it heat up which leads me to believe I'm correct.

Also from what I can see there are no condensers on my bike next to the coils. Could this be part of the problem?

The coils are after market eBay ones changed by the previous owner I suspect.

[Steve]

Condensors would be near the points, not the coils.

If you can still separate the coil wires, measure the resistance of the coils. Should be about 4-5 ohms if you have points.
Could be closer to 3 ohms if you have electronic ignition. (Electronic ignition will have no condensors.)

It is somewhat normal for a coil to heat up when in use, but when in use, it will see intermittent current because the points open occasionally.
Sitting there with the key ON and the engine not running is not "normal operating conditions" and will not help anything.

.

[tatu]

If you leave the ignition turned on without running the bike one coil will warm up as they are only supposed to have intermittant open/close from the points. It is a good way to cook your condenser and burn the points.
I would check the coil impedance and megger it and if its the same as the other call it done.
It will only heat one coil because the other set of points will be open.
You will notice that if you turn on the ignition and flick the kill switch off, the neutral light will get brighter. That is your ignition circuit consuming power and causing unnecessary load.
(Possible this also caused the fuse to blow too)


What Steve says

[jave101]

Thanks for the help guys, I did have the ignition switched on for a fair few minutes by accident so this is probably why the coil overheated and blew the fuse.

The manual for my gs400 shows the condensers mounted on the rear stand off mount for the coils not next to the points. There aren't any condensers on the points plate either. Could be why the previous owner had to replace the points and they were arcing.

Old skool that wiring diagram doesn't show the primary and secondary coils and how they are wired. The GS400 diagram on bikecliffs website and in my manual show the individual coils and their wiring.
My understanding is that when the ignition is on there is power to the primary coil and when that point is closed it earths out, but when the point is open it allows the secondary coil to charge and fire the spark plug.

Please correct me if I'm wrong I'm still trying to get my head around how coils and points work, I've been spoiled with CDIs my whole like

[pete]

Hey James, yep that's right. Coil turns "on" by grounding through the points, then they open which turns the coil "off" and lets it discharge and fire the spark.

Electronic ignition (GS' have transistorised ignition not CDI's) operates the same way, but grounds via transistors rather than the points.

[jave101]

Ok brilliant thanks for the help.
Now it's only a matter of getting the bike to run above idle haha. Once again out of my depth when it come to carb rejetting.

[barnbiketom]

Jave may I ask why you are thinking it needs re-jetted?

is it stock or does it have pods?

if stock there is NO reason to re-jet.. the carbs are simply plugged up.

[jave101]

It's got pods and hotdog mufflers, just ordered some k&n pods to replace the crap ones I bought it with.
Ill be tearing the carbs down again tomorrow and putting them in a carb dip then rebuilding and seeing if that helps at all.

[barnbiketom]

Gotcha!!

maybe someone with a good recipe for that configuration will chime in and help with a concrete starting point for the jetting?

If you start it up and hold your hand over the pods,or cover them up slightly, will it run better?? i bet.

[pete]

Damn Pete, I'm just getting up and it's time for you to go to bed

Haha yes indeed! In fact I'd logged off before you posted

It's got pods and hotdog mufflers, just ordered some k&n pods to replace the crap ones I bought it with.
Ill be tearing the carbs down again tomorrow and putting them in a carb dip then rebuilding and seeing if that helps at all.

What dip are you using? I used Yamalube carb cleaner for mine as that's the only one I could find...

[jave101]

Well this is good no one sells yamalube carb dip. Only the generic carb cleaner spray. Awesome

[SqDancerLynn1]

IF you have pods and such Did it run before ?? It would have a hard time starting without jetting

[jave101]

Yeah it runs pretty good on idle but any throttle and she backfires and bogs down.

[pete]

Just buy the carby cleaner on line James...

http://yshop.yamaha-motor.com.au/products/carburettor-cleaner

I lucked out and my local Team Moto had a bottle on the shelf.