Topic: Sudden Death....

[CBRat]

I started my bike this morning and started down the street and while at an intersection the bike died instantly.  All power is gone completly.  No lights, ignition, nothing..  I am just trying to figure out where to start trouble shooting.  The main fuse is OK. I have my multimeter ready.. any ideas?

Bike: 73 CB750

[skidpan]

Into the headlight and start jiggling connectors, check the connector from the ignition switch and replace the main fuse anyway, I had one that had one end cap come loose and cause intermittent shutdowns, but would test ok.

[VitaminCB550]

Put a new fuse in the main. I know you said it looks good but I've had this happen to me a few times. The fuse slowly melted inside where the metal is.

[scondon]

Put a new fuse in the main. I know you said it looks good but I've had this happen to me a few times. The fuse slowly melted inside where the metal is.

   I'll second that. The main fuse tends to break at the end and not melt in the middle. Gives the appearance that it is still good when it isn't. If that doesn't work I'd look into the connections leading from ignition switch to harness.

[hymodyne]

I had a connection break inside the kill switch... had to re solder

hym

[Ceej]

the same thing just happened to me the other day. (I made a similar post to yours) and i have finally diagnosed it as a bad ignition switch

[78_SaltLick]

id check the battery out first, could have a bad cell. take your battery out and take it to a battery shop and have them hook it up and make sure its good, then id go for the rest.

[78 k550]

My 72 500 just started doing this. I tracked it down to the conection on the starter solinoid. You might try there.

Paul

[gmuse2]

I started my bike this morning and started down the street and while at an intersection the bike died instantly.  All power is gone completly.  No lights, ignition, nothing..  I am just trying to figure out where to start trouble shooting.  The main fuse is OK. I have my multimeter ready.. any ideas?

Bike: 73 CB750

I have had the same thing happen with my old dodge truck and it was the chassis ground strap coming loose. I don't know if the bike has the same set-up since I am a newbie to the fine art of keeping these old rascals running. I agree with the others who say change the fuse. I have had fuses that blew, but then made contact on the end cap so that by the meter they looked closed, but would break contact when moving and jostling around. I hope you get it fixed soon and cheap, good luck

[Green550F]

My 550 was struck by lightning once! Damn lucky it didn't fry the computer!

It was in the garage and the bolt hit the garage, arce to the door opener and then to the bike . Identified by the burn marks on the mirror and engine case.
The only real damage was to the wiring harness. A ground wire broke where 4 wires soldered together. lights worked but no ignition.

[quietlikeachurch]

Definitely try a new main fuse first.  If that doesn't work, then move to the ignition switch.  I've had switches fail on two different bikes...one just shorted completely, the other could be coaxed to run by wiggling the key.

-Ian

[Andrew Foss]

same thing happenned to my 76 750f. the previous idiot...i mean owner...had rewired the strater switch because there were broken wires in the handlebars, when he rewired he used too lage of a wire and the excess amperage burned out the solinoid. so if you do have a broken wire make sure to use the correct size when you replace it.
-andrew

[TwoTired]

when he rewired he used too lage of a wire and the excess amperage burned out the solinoid. so if you do have a broken wire make sure to use the correct size when you replace it.

I'm sorry, but this is pure hokum. 
Wire sizes are chosen so that THEY don't heat with the current they are expected to deliver.  They are totally passive in the circuit and don't add any power to a circuit's end device.

If you had a solenoid problem, it was due to some other issue besides wire size.

Cheers,

[jph550]

Definitely try a new main fuse first.  If that doesn't work, then move to the ignition switch.  I've had switches fail on two different bikes...one just shorted completely, the other could be coaxed to run by wiggling the key.

-Ian

I had  a switch go bad on me too. Luckily I was visiting someone who had the same bike as mine. They able to loan me their switch until the one I had to order came in. One minute it worked, shut it off, talked 30 minutes later. NO work!!

everyone should have a spare bike at their friends house. 
 

[Green550F]

Exacly! that's why I have a ride right now!