To rebuild myself or have professionally done

[KiwiGF]

Makes no odds if the bike is +ve or -ve earth regarding fusing the earthed terminal of the battery.

Rex, I know a fuse can go anywhere, flow or return, positive or negative, supply or ground side, but it's good practice to put it in the supply side nearest the battery to protect as many components as possible, but yes, it will work anywhere in the circuit. It's basically terminology as to most people 'earth' usually means 'to ground' even when the negative side of the battery becomes the supply or live side.

In fact I have a fuse on both sides on my GF simply because the earth cable is longer and I can reach under the seat, pull it out to remove the fuse when working on or near electrical parts. In my case the supply or live side (being positive earth), is not easy without removing the seat first as there's lots of extra cabling, fuses and gizmos for my sidecar on that side.

Rog.

I know it takes a certain set of circumstances….but on my B44 its possible to get the battery terminal to short out on the frame……when removing it, or if for some unfathomable reason it came loose in it’s holder, so an earth fuse definitely has an advantage when that happens, a fuse in the supply side does nothing in those circumstances.

So I am also in fuse both sides of battery camp, plus also one in the dynamo supply wire, as the dynamo can pump out large currents, enough to cause wires to burn out, in some fault situations.

[Rex]

That'd be some fault for the dynamo to produce wire-burning current!

[KiwiGF]

That'd be some fault for the dynamo to produce wire-burning current!

Yep, a regulator fault could do it Obscure but possible (or so I have read).

[Rex]

I wouldn't think so. Burning looms are caused by battery shorts or earth faults, and the dynamo would muller itself long before it produced currents of that magnitude.

[groily]

I wouldn't think so. Burning looms are caused by battery shorts or earth faults, and the dynamo would muller itself long before it produced currents of that magnitude.

Yup. A classic being a mechanical cut-out that fails to open as revs drop leaving the battery connected directly to the dynamo. Park and walk away, and a few minutes later, bacon-and-eggs sizzling noises and risk of losing the vehicle.
Was at the 'Great British Picnic' at the Shuttleworth Trust at Old Warden Aerodrome once, a long time ago. One of my favourite places on this earth, 'the Right Crowd and No Crowding' and all that.
A beautiful open XK120 Jag, newly- rebuilt, was making audible sizzling noises in the car park as a mate and I strolled past. Ammeter off-scale (-30A maybe on that) discharge visible for all to see, along with smoke and smells. Two of us wrenched the bonnet open brutally, ripped out handsful of burning wiring and snapped off a battery terminal violently.  Total catastrophe thereby avoided.
An expensive lesson for the Proud Owner, who was initially hopping mad that we'd buggered up his car. Until it was explained by persons other than 'you unspeakable vandals' that the choice was the wiring, regulator and battery etc, or a whole car - and which would he have preferred  . . .?

A salutary example of why fuses, ratings and where they are placed can be a bit critical; and why ammeters are not just for decoration.

[coater87]

 The only thing I would like to add is please tighten the bolts.

 Ran into another restored at home mustang, beautiful job. You could tell the guy really cared.

And thats why all the bolts are finger tight,  so scared to strip a bolt that they recieve next to no torque.

 Tighten it like its a dirty old lawn mower and you should be fine.

Lee

[chaterlea25]

Hi All,
A couple of years ago I bought a Guzzi GTW single, it needed some basic fettling as it had not been on the road for some unknown time, anyway before I got to go through the wiring and charging system I put a new Cyclon battery in the hollowed out battery in order to have a brake light in preparation for a vintage event
Day one went fine, next morning when I stuck the key in the  switch and checked the brake light, and no light lit 
I checked the 10 amp fuse and it was OK, so with no more time available that morning I rode on for the day a bit nervously if anyone was riding close behind..
That evening I pulled the battery, to find it all swollen and out of shape , Thats that fkd I said
After the week long event I got time at home to go searching for the "fault"
It turned out that the dynamo must have woken up and after riding about for the day the cutout must have stuck closed
The battery discharged into the dynamo and burned it to a crisp, the wiring was not affected or the 10 amp fuse did not blow!!
Whatever the resistance of the dynamo was it was high enough to not draw enough current to blow the fuse and low enough for the wiring to handle ? but still cooked the dynamo????

As Marelli dynamo's are only 30W and secondhand ones cost a mint, as do modern replacements I fitted a Lucas 60w
as they are the same diameter and have the same shaft taper as the Marelli it was straight forward,
I made a plastic adaptor and a small bracket to fit the Marelli end cover onto the Lucas, added a DVR2 and new battery. All has been good since

John

[Richard Hinton]

If you have stripped the the top end down and got to piston level, then you should be ok. you may need some tools tho to rebuild eg a comb for the push rods can take 1 hour or all day. but I always take pictures in the process sometimes useful. Get a manual for some info I have a Haynes but really is crap but it does contain some settings etc.

[limeyrob]

Its important to stop as soon as you are unsure and post pictures and questions on here.  I've seen too many engines ruined by people pressing on when they should have stopped and asked.