1972 Honda CB750 K2 - Blowing my fuse

[Jrperida]

I replaced the old harness and fuse box with new ones but I'm still blowing my 15a main fuse. It mainly occurs when I'm kickstarting the bike and intermittently when i turn the kill switch from off to on position after I turn the key. I checked all my connections and grounds, all seem to be in good order. I feel like something is drawing too much power when I kickstart the bike, the coils perhaps?

 

[Sonreir]

Probably not drawing too much power, but there might be a pinch in a wire somewhere that's eaten through the insulation. Check all of your black and black/white wires to make sure they're all in good shape and there isn't any metal poking out from behind insulation.

 

[Jrperida]

I've double checked all my wires and no signs of pinches or any bare wire sticking out. I can't figure out another way to diagnose the situation. My thoughts were leading to the charging system, perhaps just change out the regulator and rectifier for a dual solid state rectifier/regulator.

 

[Jrperida]

I manage to narrow it down to the coils, when I disconnect the black/white from the coils to the harness it allows the bike to stay on without blowing the fuse. I checked the coils itself on both the primary and secondary with the multimeter. Everything seems to be in spec. However I did notice ignition coil for 2 & 3 was running hot when I would try to start it. Is that normal? Wondering if I should just replace both coils, contact points and condenser just to be safe

 

[irk miller]

The coils are filled with oil to keep them cool, so heat is normal to a point, however they shouldn't overheat. I would replace them.

 

[pidjones]

On a points bike, the 12 volts should only see ground (through the coil) when the points are closed. That should aid in checking for your issue. Some coils are rated for much lower voltage (like or 2 volts) and draw a lot of current with key ON and points closed. They will heat up.

 

[Jrperida]

Swapped out the points and condenser. Finally ran on the first kick. So far it ain’t blowing a fuse so i’m pretty stoked.