Nighthawk is shorting out and blowing main fuse

[zephyer]

Hello all, recently bought a 1992 honda nighthawk 750 from salvage yard and have put everything together but found the main fuse was broken so i replaced it and as soon as i did and put the bike into neutral it blows the fuse. i have checked the neutral switch and i believe its working as it should because its only function is to complete the circuit to ground when the bike is in neutral(correct?) i ordered a new clutch diode because mine seems to be faulty(tested with meter and it lets electricity pass through both ways) but that still shouldn't explain why theres a surge of over 30 amps going through the main fuse. any ideas?

[motogrady]

I'd start by checking for continuity from the wire leaving the main fuse box to ground, (the frame),
with it disconnected from the battery side.

Then unplug every molex connector from there downstream to the various items that it feeds, one at a time,
checking continuity to ground as you go.

No short down stream, unwire the fuse box , leaving it mounted to the frame, check it itself.

The continuity stops, it's somewhere in that area or component.

Good luck and let us know what you find.

[zephyer]

thats what i did to verify its grounding out at the neutral switch, i tested everything else for ground because it doesnt ground out if the bike isn't in neutral

[Re-run]

So, it only happens when you go to neutral? I'd start with unplugging the wire for the neutral switch, then try the wire going to the neutral indicator light. I don't know about the 92, but it is possible it has a kill switch for when the kickstand is down, if the bike is in gear it will kill the engine. I would test this wire, also.

[TOOLS1]

I hate that kickstand switch. I have seen it go bad, or where the kickstand is not going all the way up, and the bike dieing as you try to pull away, and it is so frustrating. However it should not blow the fuse. You are correct with your understanding of how the neutral switch works by grounding the circuit. Since you have narrowed it down to that circuit, all I can say is to start tracing the wire for that circuit. I have seen wires broken/cut inside the loom along the frame backbone, and where they go into the back of the headlight.
TOOLS

[zephyer]

thanks for the helpful replies, there is no kickstand switch(im glad because id rip it off) and i have no instuments plugged in so i only know its in neutral when i can roll the bike around(no headlights or anything either. im currently buying a new cdi box and i bought a replacement clutch diode because i tested mine with a multimeter and it measured shorted both ways, this however doesnt really help me understand even if it was shorted was would allow a full draw across the line that would short the 30amp fuse.

[TOOLS1]

The neutral indicator light supplies the load for that circuit, so that it does not blow the fuse as a short would. You must have a (HOT) wire connected to the neutral switch without any light connected in circuit. This would immediately blow the fuse when the bike is put into neutral.
TOOLS  

[zephyer]

so thats why it keeps blowing,thanks. What type of resistor could i use until i get a instrument cluster?

[TOOLS1]

You need to find out how you are getting electricity to the neutral switch without it going through the indicator bulb. That is why you are blowing fuses. Resistors are not needed for any circuits on your motorcycle. Other then the AC current from the alternator every thing on the bike uses a straight 12 volts.
TOOLS  

[zephyer]

Tested everything for ground and the only thing I found that looks to be the main cause is still the clutch diode, it has no resistance going to the neutral switch which I belove is causing a ground?

[zephyer]

Tried a new clutch diode and it arced a died, ordered a new wiring harness and will see if something withen itself was the issue unseen.

[zephyer]

currently testing the regulator/rectifier is there supposed to be random connectivity when just throwing the multimeter around different points? i tested with negative lead on the R/W input wire terminal and each of the stator wire inputs tested ~600ohms, but when i put the posite on the BL input lead i dont get anything except from the white wire section. the manual doesnt really tell me any readings im supposed to get so if someone could check with theirs and let me know if i need a new one of if those readings are correct? Thanks