ignition circuit electrical short

[perpetualmechanic]

I was riding my buddies bike to bike week. It made it all the way there, but getting ready to come home, the starter shorts out everything electrical, lights, dash, etc when its queued up. Any ideas on what to start checking? I don't have a wiring diagram, so any suggestions would be great. Also if anyone has knowledge of tests I can perform, ie voltage or resistance checks of certain components, that'd help too.

Everything else on the bike works. I rode it all the way home (100 miles or so) by bump starting it and then not keying it off until I was home. I've verified that the starter relay works. To my knowledge there isn't anything else in the starter loop but the starter and the relay. My guess its a high current wire because when the power shorts out, the battery voltage drops down to around 1V. Any suggestions would be appreciated.

[KatanaJim]

Fuses????

[perpetualmechanic]

Not a fuse. Electrical power comes on when the key is in the on position, and immediately gets killed when the start button is pressed.

[Smoke-Dog]

Sounds like a loose wire, maybe your ground is loose or dirty if the fuses are ok. Check your Negative from the battery to the frame and motor and see what you get. Hopethis helps and good luck.

[The CyberPoet]

The most likely places for you to have a short on that bike are:

(A) the wiring harness where it passes outside the frame to the right of the engine;
(B) the wiring at the ignition switch;
(C) the actual control switches on the handlebars (esp. if the bike sees driving rain or a pressure cleaner)
(D) the main cables to the battery, AND
(E) the 20-pin molex connectors above the headlights that lead to the dash.

If it's not blowing any fuses (including the main fuse), it would imply the problem lies in the switch itself or in the wiring on the far side of the relay going to the starter.

Cheers,
=-= The CyberPoet

[Black_peter]

Since it's a pre 98 with no head light cut out (right?).
What about a short at the starter itself?

And yes all the wires from Battery-relay-starter are at least 8AWG..

[perpetualmechanic]

If I remove the negative cable from the starter relay on the LHS of the bike and press the starter button, I can clearly hear the relay click on, then off, in synch w/ when I am pressing the button. When I reconnect the cable, it shorts out again. This makes me think that its not something up in the dash area but more directly related to the starter motor itself or its wiring. Maybe this will help describe the situation a little more clearly.

[Black_peter]

If I remove the negative cable from the starter relay .

Ummm clear that up because there is no negative cable..
The starter has four wires.

Two on the top center that lead to the button (power and ground)
One coming in from the positive lead of the battery (left side of relay)
and one going to the starter (right side).

Either way, are you are saying that if you remove one of the large wires from the relay, the relay clicks and if you connect it, the relay doesn't ?
You need to try removing both wires (one at a time)..

I suspect you will find that the short is in the starter.

[perpetualmechanic]

Correct, if I remove the black, heavy gauge wire from the starter relay, you can hear the relay click as it should when the start button is pressed.

When both heavy gauge wires are connected to the starter relay, the relay again clicks as it should, but then the short occurs and the battery voltage drops down to around 1V.

It is my belief that the relay itself is performing as it should based on the audible click in either scenario (heavy gauge wires connected or disconnected). I'll try removing one at a time and see if there is anything else I can observe.

[Black_peter]

Ahh good info!! but hold on!!
I think you have all the information you need.
I highly doubt the problem is from the battery to the relay!! It is in your starter (99.9%)
Removing even the starter wire from the starter is a major PIA (IMO!!) I'm sure if you take a multi meter and read the resistance from the loose right side wire from the relay to a good ground (say the negative of the battery) you will read damn near zero. I think you have a short in the starter. I wonder if anyone knows any ways of moving the starter? If you get the starter to rotate you might find that it is on a "bad spot" Here let me illustrate!
In the pic below you can see the brush, this carries the voltage to the commutator, (a series of plates) when the voltage enters the coil of the motor (labeled #2) the motor moves a bit, bringing the brush to the next commutator and it moves more (it's a bit complicated but anyway) If there is a short in one part of the starter the brush (that gets connected to the battery when you push the start button) and could be getting sent right to ground (full short). If you could turn the starter the brush would now be on a different (hopefully good ) part of the starter and at least kick a bit. Sometimes the starter can run fine as long as it doesn't stop on the bad spot (it rides over the bad spot when spinning) I don't think you have a full short really, if you did the fuseable link (in the starter relay?? ) should have blown, or maybe someone monkeyed with that part. The key here is to be 100% sure it is the starter before pulling it..
I have tried to get to my starter and I think the carbs have to come out. As I have mentioned before I have some cool tools for getting into tight spots but those starter bolts are in evil locations!!!

[perpetualmechanic]

I understand your post completely, and its actually the problem I suspected from the beginning. The one thing I can't figure out is if the commutator is shorting, where is the power going? My only thought is that it would go to the commutator casing, which grounds to the motor/frame/whatever else is really big and metal on the bike.

I've been reading online articles and I think the best way to test it would be to get an ammeter and see what current is being drawn to the starter when it shorts out. My guess is that its alot because the battery voltage drops so low on a good battery. My first test is going to be to connect the in place battery to a good battery w/ jumpers and run all the tests again to verify a good battery.

[Black_peter]

Good plan..
If you end up pulling the starter post any tips about the job.. Mine was acting funky but after seeing where the bolts are I let sleeping dogs lay..

[perpetualmechanic]

I went ahead and pulled the starter. I tried a really long shafted phillips screw driver and squeezed it between the carbs after removing the tank, but the bolts were torqued too hard and I stripped the head. I figured this would happen, but its ok, because they fit a hex wrench, and this is the proper tool anyways. I had to pull the tank, airbox, and carbs, but turned out to be a relatively small job. Make sure your gas tank is filled no more than about half way, so you can store it on its side (I don't believe there's a master off switch on the stock petcock).

The airbox and carbs were easy to pull. The only tool used was a small phillips. Obviously you have to remove all the hoses and wires to the gas tank, which isn't a big deal. The only other cord I removed was the choke. I left the throttle cables alone (apparently there's two of them, no idea why), and just moved the whole assembly out of the way. I also had to pull the oil lines to get to the forward bolt of the starter, but after that, they came out just like they should. We'll see if it all works after I put it all back together.

Does anyone know what years are compatible for that starter? I've found a couple cheap ones on ebay, but they're from early 90's bikes, the one I'm working on is a 98. They look the same, but you can never be too sure, and its impossible to find compatible part numbers online. Everyone makes their own part number so you can't google the number. Bullshit.

[Black_peter]

Geez!!
What a lot of work.. I once changed the starter on my Honda while talking on the phone.. Honestly, start to finish.

Good write-up. One tip I forgot to mention; I hear you can take the carbs off with the air box attached. Why?
Getting the air box back on can drive you crazy!