Fuse values?

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Quello Serio
Posts: 20
Joined: 30 Jan 2017 10:17
Location: Dublin, Ireland

Fuse values?

Post by Quello Serio »

Can anyone tell me the correct value for 350 fuses please? Some of mine are partially melted, but still working, and the values seem very high (one is 16A?). Bike used to have an electric start, but thats long gone.
morini_tom
Posts: 920
Joined: 05 May 2006 13:47
Location: Northampton

Re: Fuse values?

Post by morini_tom »

16A sounds a bit sporty! Are you talking of a single main fuse in the power feed to the fusebox or the 3 individual fuses inside the fusebox?

I'm sure someone will come along with a proper answer in due course, but on the basis that a Morini has a 150W (or less) alternator, then you wouldn't expect much more than 10-12 Amps from the charging system, and similarly even with all your lights on you shouldn't be drawing 150W (21W stop light, 5W tail, maybe 60W headlight and 42W for a pair of indicators).

The starter motor power feed to the solenoid is direct, unfused and the relay doesn't draw much so the starter motor current doesn't need including otherwise you'd be blowing fuses all day long.

And remember the morini ignition system has its own self generating coil, so you are not using the main electrical system at all for sparks.

All the above of course assumes you have a standard setup. Add coil ignition, massive headlight bulbs, heated grips etc then you will increase your max current draw.

Often what happens with older bikes is a wiring fault occurs, a fuse blows and somebody replaces it with a bigger one. All you are doing is throwing power away and possibly overheating wires or whatever component is on its way out. Worth checking the wiring over to identify where there is an issue, because if you are melting 16A fuses then there is a lot of energy going somewhere. Aside form the electrical and potential reliability issues, sorting this would also give your alternator and battery an easier life.
Quello Serio
Posts: 20
Joined: 30 Jan 2017 10:17
Location: Dublin, Ireland

Re: Fuse values?

Post by Quello Serio »

Main fuse is 16A; the others are (from left to right) 10A (Green), 15A (Brown), unmarked(Black)
JonD
Posts: 37
Joined: 14 Jan 2014 10:40
Location: Wantage

Re: Fuse values?

Post by JonD »

I'm surprised nobody has given you an answer on the fuse ratings. I checked my Morini handbook and Blue book and no values. My main fuse is 16A and the three in the fuse box are all 15A which seem too high as it gives no effective discrimination between the main fuse and the subsidiary fuses. I checked the current on each fuse in the fuse box and got the following values going left to right, 3.75A, 4.75A, 1.5A. I have order some replacement fuses and will try 8A, 10A, 5A in that order.
If the fuse bodies are melting and the fuses are not blowing I suspect you have poor connections between the fuses and the fuse box connections which will generate heat and melt the the fuse bodies. The spring tension on my fuses is quite high making it quite difficult to remove the fuses.
The bike is a 1979 3 1/2 Sport with electric start.
Hope this helps.
Quello Serio
Posts: 20
Joined: 30 Jan 2017 10:17
Location: Dublin, Ireland

Re: Fuse values?

Post by Quello Serio »

Thanks very much for that. The spring tension is very high on mine too, so I don't know if a poor connection is a cause - if anything, the one that melted is tighter than the rest. I've replaced my melted & unblown 10A one with a 5A, and my dodgy-connection-inline one with a 15A blade fuse. I'll see how that goes.
George 350
Posts: 450
Joined: 16 Jun 2007 09:43
Location: Northampton

Re: Fuse values?

Post by George 350 »

If it were mine, I would give the wiring a good check too. If the wiring is original, there is a good chance that the creeping 'black death' on the cores has occurred, increasing the resistance along the wires and especially at every connector. Can occur almost anywhere but handlebar switch wires are particularly vulnerable (and are incredibly thin too).
If you do have this, then the only real cure is to replace the affected section of the loom with a new one.
Regards, George
George
350 sport 1978, 350 Strada 1978
650 Norton 1967, 650 Kawasaki 1977 and 650 Enfield 2019
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