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Author Topic: Bike won't start  (Read 1459 times)

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Offline dramsell

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Bike won't start
« on: April 20, 2009, 04:48:29 AM »
I have a 1978 CB 750K and it will not start. 

Put the key in and no lights, nothing.  Checked the battery with a meter and it is at 12.8. 

Then I took a screwdriver and crossed the posts under the sidecover and it turns over. 

I am guessing it is the ignition switch-any thoughts?

Dave R
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Offline Hush

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Re: Bike won't start
« Reply #1 on: April 20, 2009, 04:50:57 AM »
I'd say you diagnosed your patient well Dr Dave, you could also check your fuses, the mains fuse and the accessory ones, I'd put my money on a blown fuse. ;)
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline dramsell

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Re: Bike won't start
« Reply #2 on: April 20, 2009, 04:54:22 AM »
Thanks. 

I did check all the fuses first though and they are all good.

Dave
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Offline my78k

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Re: Bike won't start
« Reply #3 on: April 20, 2009, 05:01:03 AM »
If you have a spare I would throw one in just to be sure. The tube fuses can separate at the end (burn through or vibration) where it is difficult or impossible to see.

Dennis
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Offline Hush

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Re: Bike won't start
« Reply #4 on: April 20, 2009, 05:05:13 AM »
If not fuses then wiggle your ignition with it turned on and see if the idiot lights come up.
Honda ignitions are known for the arse dropping out of them and it all becomes too loose.
Does the bike actually start if you cross the solenoid with a screw driver?
If it starts you can discount bad earth, bad solenoid etc and start heading up front where the ignition probably isn't getting any juice. Edit, sorry it won't start without the ignition will it ha ha dummy me
Does your bike have the large 30amp fuse beside the battery and the bank of 20 amp ones between the bars? probably not.....I run a CB650 so I'm just kinda shooting in the dark here and hoping that generalising will get you running again.
It's like midnight here in NZ and all the helpful guys over your way are probably at lunch or something! ;D
« Last Edit: April 20, 2009, 05:07:38 AM by Hush »
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline dramsell

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Re: Bike won't start
« Reply #5 on: April 20, 2009, 05:12:08 AM »
Well it turns over when you cross them.  I have replaced all the fuses and the block with the 2 prong type a couple of years ago.

Dave
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Offline Hush

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Re: Bike won't start
« Reply #6 on: April 20, 2009, 05:26:36 AM »
Wiggle the block connector at the back of your ignition with the key on, you'll probably see the lights come up then.
Oh yeah about lights....do they work? your horn? indicators?
Kill switch "ON".....ok but I've done it myself. ;)

Honda starting circuits go: battery-solenoid-kill switch--ignition switch.

So you say you battery is showing voltage, solenoid turns bike over, kill switch on, does starter button turn bike over?
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline dramsell

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Re: Bike won't start
« Reply #7 on: April 20, 2009, 05:47:57 AM »
No, it does not.

Dave
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Offline burmashave

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Re: Bike won't start
« Reply #8 on: April 20, 2009, 06:31:09 AM »
Quote from: Hush on April 20, 2009, 05:26:36 AM
Wiggle the block connector at the back of your ignition with the key on, you'll probably see the lights come up then.

That's what happened to mine. The connector under the switch broke. As I recall, it was the plastic pin/arm/thing that snaps the connectors together. With the connectors loose, the wiring harness end just slipped out. At any rate, I had to replace the switch (or get very creative).
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Offline Hush

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Re: Bike won't start
« Reply #9 on: April 22, 2009, 02:54:17 AM »
OK pull the back off the ignition and check it out for missing bits, if it still looks intact then bridge across the contacts with a feeler wire until your idiot lights come up.
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline dramsell

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Re: Bike won't start
« Reply #10 on: April 22, 2009, 04:18:21 AM »
Looked at it last night and it appears that the switch is intact.  What other things could it be?

Dave
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Offline Spanner 1

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Re: Bike won't start
« Reply #11 on: April 22, 2009, 07:34:09 AM »
The headlight supply passes thru' the start button on your bike so that when you press the start button the headlight turns off while the starter is cranking the motor...anyway, even if the start button was fried, the tail-light should always come on when you turn the key....sounds like it's not coming on, so I'd take a closer look at the fuse block, including the back of it and it's connections.....BTW, key 'on' all black wires on bike should be 'hot'
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Offline dramsell

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Re: Bike won't start
« Reply #12 on: April 22, 2009, 07:36:44 AM »
Thanks.  I will try checking the fuse block again tonight.  I had it replaced with the more modern 2 pronged fuses and new block about 3 years ago.

Dave
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