Topic: Main fuse blown

[andy1976]

Help I'm in the s*!t big time. I've been checking my bike over prior to this weekends trip away. Everything seemed fine until electrics went dead. I checked the main fuse, fine,connector blocks etc, fine, it turned out to be loose ground wire on the battery.
The trouble I'm having now is that when the bike starts and the rev's hit 2000+ rpms, it's blowing the main fuse, it doesn't do it when on tickover.
I don't know what to look for and I'm supposed to be going away tomorrow morning 
The bike ran fine until now. 

Thanks
Andy 

[razor02097]

whats "tickover"?

Check your battery with a multimeter to see if you are charging the battery and that its not hitting high voltages.

Also check under the front fuse panel to see if anything is up there too.

[andy1976]

Hi
I meant to say when the bike is running at idle (1000rpm).

[mlinder]

Had a similar problem on the KZ650. The bolt to the leads to the coil we're barely apart, and the damned thing would arc once you got a bit more juice headed up there, and it would short, and blow the main fuse.

Not saying it's the coils, but it's likely something shorting out that needs a little more juice going through to blow the main fuse.

[750goes]

do you have the correctly rated fuse in the fuse holder

[andy1976]

The fuse I've been replacing is rated 15amps

[razor02097]

Isn't the main fuse 30A?  The others are 10A

[andy750]

Isn't the main fuse 30A?  The others are 10A

No! The main fuse is 15A (CB750, CB550).

[Patrick]

And the others are 7 amp.

[razor02097]

Isn't the main fuse 30A?  The others are 10A

No! The main fuse is 15A (CB750, CB550).

Woah ok ok... didn't see model of bike...  mine has 30A main and 10A at handlebar fuse panel thats why I asked  

[andy1976]

I forgot to put which model my bike is in my first post (oops!), it's a '76 CB750F1.
One of the guy's on the UK site reckons my regulator is faulty, How do you test it using a multi meter? I've not done this before.

Thanks

[andy750]

Woah ok ok... didn't see model of bike...  mine has 30A main and 10A at handlebar fuse panel thats why I asked  

Eh...and which bike would that be 

[razor02097]

Woah ok ok... didn't see model of bike...  mine has 30A main and 10A at handlebar fuse panel thats why I asked 

Eh...and which bike would that be 

I was talking about the 30 amp fuse element on the starter solenoid.  I thought that to be the main fuse he was talking about... Jesus...

[andy750]

I was talking about the 30 amp fuse element on the starter solenoid.  I thought that to be the main fuse he was talking about... Jesus...

You have lost me....what 30amp fuse on the starter solenoid? I asked a simple question -which bike are YOU referring to??

And my name isnt Jesus..its Andy 

[mlinder]

I was talking about the 30 amp fuse element on the starter solenoid.  I thought that to be the main fuse he was talking about... Jesus...

You have lost me....what 30amp fuse on the starter solenoid? I asked a simple question -which bike are YOU referring to??

And my name isnt Jesus..its Andy 

Hi Jesus.

[the technological J]

if u end up in a pinch for a new regulator... theres a thread about one for a ford truck or another one from radio shack.. for a fraction of the price...and might be more readily available

[razor02097]

Andy I have a 650 I wasn't calling you Jesus I was saying that at then end with a defiant tone.

[bryanj]

You need to check voltage at battery under all conditions before condeming anything. It could be just something vibrating into a ground contact when reved.

Generator voltage would have to be way high to blow fuse cos of overcharge BUT the resistor on the reg could be shorting as it switches in, Never had one do that but nothing is impossible with age