900Ss/916 alternator

[welshmally]

Hi there,

At some point I will be putting a new wiring loom on my '80 900SS, but in the mean time, I want to boost the output from the alternator, and I have a couple of queries:

I have heard that the alternator from a 916 is a direct slot-in, and pretty much doubles the output (I can then have the headlight on AND indicate!), but will this over-stress the rest of the system until I re-wire?

Is it true that it's a straight slot-in or is any machining required?

Is it worth waiting and putting in the later 3-phase unit when I re-wire?

Thanks

Hugh

[radecal]

G'day Hugh,
Two issues.
Number 1 is the switch to the 916 alternator. Not sure it is a straight drop in. This was discussed in detail on the Bevelhead List recently regarding 750 roundcase engine upgrades. Some info was provided on the squarecase models but I can't remember the details. I can check back to get the info if you can wait until I get home (on the road with work at the moment).
Number 2 is the headlight. The headlight switch and wiring carries the current from the battery to the headlight and will over time suffer not to mention causing voltage loss. Boosting the output can make all this worse but can be fixed easily with a headlight relay. A member of the Bevelhead list makes and sells a miniature headlight relay (Matchbook Relay) that fits in the headlight shell and gives full power to the headlight and uses the headlight switch to only the signal the relay which saves it and the wiring from burning out. You could fit a relay elsewhere on the bike but this one hides in the headlight shell and has a large amp rating. I can get this info when I get home as well.
Let me know if you want the info.
Regards,

[machten]

With a 1980 ducati you should have no problems at all with sufficient watts from the alternator. Your alternator was rated at 200 watts (and let's say it was 180) should be more than enough if everything is working as it should - and it is usually reliable stuff by 1980.

I've never had a problem with post 1978 bikes in that regard - as opposed to the roundcase 120 Watt (if you are lucky) set up.

If it isn't working, I'd just fix it. (unless you're planning on a "Mad Max" look with a few spotlights mounted! )


Kev

[welshmally]

Hi Kev,

no the alternator is working, although I haven't checked exact output yet, but with the headlight on, all other electrical functions struggle a bit - e.g. indicators.

I've heard that it's worth replacing the fuse box which is seriously crappy - any suggestions for a relacement would be useful.

When I'm testing the loom, are there any areas that I should prioritise which are known problem areas?

Cheers

Hugh

[Craig in France]

When I'm testing the loom, are there any areas that I should prioritise which are known problem areas?

FWIW: Check the condition of the wires into the reg/rec.

Ciao

Craig

[machten]

Hi Hugh,

I've had symptom of slow or non existant flashing of indicators (light stayed on) which proved to be an earth problem. I can't remember the details other than the same thing happened despite testing immediately after installing a freshly recharged and trusted battery. May be a total red herring, but perhaps worth bearing in mind.

Regarding the fuse box, I had some problems with mine over a long period of time and in a fit of pique back in about 2005 changed it for a blade fuse box off some Jap bike . Never had to change a fuse or had a problem since.



Kev

[radecal]

Roundcase was an easy fix and now heaps better than a squarecase.

[radecal]

Hi Hugh,
If your headlights and other lights are struggling, you may have to look at all your connections as well as the previously mentioned earths and fuse panel.
As per my previous reply, the wiring for the lights runs through the headlight switch blocks and over time this wiring and the switch blocks cop a caning. All this adds up to little losses here and there and the system can get marginal especially at low revs.
Best fix is to go over your wiring and check it thoroughly making sure the earths and fuse panel contacts are clean. Then fit a headlight relay into the circuit and you will find a big improvement. Do this to the new wiring harness as well.
Regards,

[welshmally]

Just had an opportunity to do a bit of voltage testing. I checked the drop across the indicator switch (earth to light green and earth to blue/black) and it's around 8 volts - so this may be the problem......! (Shouldn't it be nearer zero volts?)

I don't want to rewire yet - is is worth getting a straight replacement, which will probably be second-hand, or is there a new unit that I could use without having to change the connector blocks?

Cheers

Hugh