Topic: 1975 cb400f main fuse blowing

[Richard Branston-Davis]

 
OK so I'm riding to work at night doing about 50mph when the bike cuts out and dies, thank goodness it was a moonlite night could have been nasty. Got my self to an area with street lighting and sorted the problem changed the fuse and was on my way. three weeks later the main fuse blowes again, this time right after i started the bike out side my house changed the main fuse and was on my way. since then i have notest that the fuse box which is probably the original gets warm is this normal? I have cleaned the brass clips inside the fuse box to see if it might help and on both occasions when i changed the fuse after removal one of the metal end caps came off and was burnt out at that end insted of blowing in the middle like you would expect. "please help"

[Vinhead1957]

These bikes are notorious for corroded connections causing fuse failure.  You might want to start by upgrading your fuse "box". Hondaman offers a modern upgrade with mini fuses.  The key switch is another weak spot when it comes to corrosion.  Begin by inspection of the major plugs and cleaning or replacing connections. Verify the frame and battery connections are solid and clean.  After cleaning, use a dielectric grease to prevent future corrosion. Available at most auto parts stores.

[mathbishop]

I literally just posted a thread exactly like this. Let me know how you get the problem sorted. As will I, if I get it sorted...

[Fattyflathead]

I just finished finished the electrics on my non runner I got with a burned overheated fusebox, I replaced the main fuse with a 15A auto circuit breaker and the 7.5 A fuses with blade type. Works great - those old cartridge fuses are crap.You should take an hour to run over a wiring diagram an check that all connections are good and tight and earths are clean.

[Richard Branston-Davis]

Thanks guys going to check all my connections ect next week and I have sent a message to Hondaman refrence the his fuse box thanks Richard 

[mathbishop]

Had a short under my starter solenoid.

[Runuv]

Glad u found the problem. I have  75 CB400 also had the same thing happening to me. I bought Hondamans fuse box and never had another problem.

[saavejo]

I have the same problem of the fuse box getting hot and the main fuse 15 Amp contacts getting real hot and melting the plastic before the fuse blows. I was wondering how you corrected this issue on your hondamatic.  Thank you very much!