start kills the fuse

[Guest]

Hi guys, there are 101 pages of electrical threads coming up when i search, so we're fresh living people here I figured... i'm going to try to tackle this this week-end but any trail is very welcome.
I have a gs750 1978. Stalled a few times, then she was tired to turn back on my fumbly handling.
Tried to jump start it, didn't work. she goes like dead. Battery is good. I changed the fuse. Lights go back on with a fuse. Then I tried to start her to change oil - in the hope I had just blown the fuse in the jump start - nope.
She killed the new fuse when i tried to start her - with the button, - I believe I'm too modern or not manly enough for the kickstart-.
That's it! Not lazy, i'll look it up. But if you have a clue, it'll direct my work.

[JEEPRUSTY]

Is the batter really OK what is it testing at?
How many volts.

TChese bikes have marginal regulator rectifiers and what you describe as stalling due to your fumbling may actually be the battery draining due to a charging issue.

[bhm]

Jee, thanks.
Lemme check it right now>
12.74. I charged it yesterday.
Yeah the starting has always been kinda slow but ok. I mean I start it ok. I Fup and it stalls and i restart it ok, I Fup and it stalls and i restart it ok, and Fup and it stalls and won't start ok. But sill coughing upon pressing start. As if i drowned it.
The next day, upon start, fuse was going off.

[TheCafeKid]

Simply trying to start it shouldn't pop a fuse unless there are other issues.
But, before we start down that trail, what did you jump it from? If a car battery, was the car running? If yes, you may have bigger problems. But if no, I would suggest checking the wiring leading back from the starter/killswitch button housing and into the wiring harness. Look for broken or open sheathing etc.
any place that bare wire could touch the frame engine etc could cause your issue.
Also check your gauge cluster, lights (headlamp, signals and brake) and horns and all of their wiring. Many of these circuits run along the same as the ignition path. Any place they could touch the frame and such will cause the fuse to pop.

Lastly, if the bike is in a good state of tune, and has a good battery for ignition, it should be cake to kick start. One or two bangs and she should fire. One thing to consider: just because your battery shows 12.7 volts at static reading doesn't mean it's good. Often times a dead cell will show a good charge, but put under load and it will crap out. Use your meter and check it again, but this time have someone hit the starter button and see what it reads. If it drops below 10 volts, the battery is trash.

[GSXR7ED]

bhm,

I recently had electrical issues and learned two things:

1. Never jump-start a bike with a running vehicle
2. Make sure your regulator/rectifier is grounded to the frame

Let us know how you jump-started the bike from the vehicle. (with the vehicle running or not)



Ed

[bhm]

Detail, but the former fuse - that popped - was 30A instead of 15. Maybe I should try the former configuration - since it used to work, but I wouldn't mind if the bike works as it is supposed to, with a 15A fuse.
The second - last - fuse that popped was my 15A ("only") replacement...

The car was not running when jump-starting. At my first attempt of jump start though, I grounded to the rear brake pedal.

@CafeKid, your reading test implies to pop another fuse and read the voltmeter during the second where start is pressed?

[koolaid_kid]

First, unless you don't really care about the bike, use the proper size fuse. Using a larger capacity one, especially twice the capacity, is asking for a fire. If you choose to use a 30, I suggest two things:
First, take the bike outside, away from any buildings or other vehicles.
Second, have an A B C class fire extinguisher right next to you.

I am serious, electrical fires next to gasoline is a bad thing.

What you need to do is use your Ohm meter part of your multimeter and look for the short. You have what is known as a direct short. Don't bother trying another fuse until you find and fix the direct short.

[kingofvenus]

Once i was jetting the carbs on my 750 and when i reinstalled the throttle cable, i pinched one of the kill switch wires and caused it to short to the handlebar, and pushing the start button would blow the fuse.

[bhm]

So a new 15A blows right away, after making sure no short in the throttle box.
A 30A works well as before without the bike blowing up. But bike won't start. Battery drops to 10.4V when pushing start.
After bashing my thigh on the front foot-peg, I can tell the kick start won't do it.
And after the third tentative to start, the battery won't push farther, yet neutral light will still be on. Sounds like a dead battery or what?

[tom203]

30 amp fuse is going to lead to disaster- PO must have had some problem which he has graciously passed to you.
Turn headlights off. So if you just turn ignition on (NO start), your fuse doesn't blow? When you press starter button, apparently the extra current draw (or wiring) is blowing fuse.
Do you know how to "jump" the starter solenoid? this will bypass the starter button circuit - unplug the trigger wire to solenoid, apply 12 volts plus to this spot on solenoid. BUT MAKE SURE you are on centerstand and neutral!!!

[bhm]

Solved!

All right, problem solved.
Kingofvenus was right, there was a short in the starter switch box. Electrical tape on the handlebar fixed the problem.
I then changed the switch box and the bike works fine on a 15A fuse.
The 30A fuse:
I think PO was kinda going around the occasional short with the 30A.
tom203 and koolaid_kid are right too.
The 30A made some connections heat up. I don't think if would have caught fire easily, but I am glad it didn't damage expensive electrical parts.
Battery was fine.
Bike works like a dream,
Thank you guys!

[koolaid_kid]

Kool news. Glad you found the issue, rather than bypassing it.
Good riding ensues!