Re-wiring, Part 4 (Starting to build the main loom) – 28 Nov 2015

If you remember, I laid out the old, manky main loom on the bench and took off the sleeving and insulating tape so that I could draw my wiring diagram. Now I needed to put it on the bike so that I could examine how it was laid out.



This is what I came up with.

Final wiring loom layout

It’s impossible to see what’s going on in that photo so here’s my pdf document – Final V7Sport wiring loom layout. This can be zoomed in on or printed out as a poster. It’s designed to come out as a 3×3 poster using A4 paper but 3 sheets should come out blank. It’s the only way I could get it to work with my printer.

The first thing was to go back to the old loom and measure for the main sections of sleeving and to mark where groups of cables need holes to exit. The various individual wires could then be threaded through and temporarily held together in bunches with smaller diameter sleeving. This gave me my loom, incorporating my modified wiring, but without any terminals fitted.


I now needed to offer it up to the bike to be sure all the wires would come out in the right place and would not be too short. For this to work I needed my replacements for the original fuse box and starter relay in place.

This is the fuse box I’ll be using.


The original fuse box had an internal link. I couldn’t see an easy way of doing this inside the new box.


So I had to produce an external bridge cable. Note the “piggy-back” terminals at each end.



Fuse box fitted to inner mudguard. It’s not as pretty as the old one but is going to be more reliable.


I need a different starter relay and wiring to the original because I’m using a later pre-engaged starter motor.This is the old type relay.


The replacement 40A relay and its connector were fitted to the original bracket. A screw is also needed in the unused mounting hole in the bracket as the rubber cover is held on by latching over the two fixing nuts.



The switch loom was fitted so I can establish where its connections on the main loom need to be.


This loom passes through lower hole in left hand side of the frame gusset.


I went back to my new main loom on the bench and fitted the terminals to the wires which connect to the fuse box. I could then work forward checking the layout of the rest.


Having done this, I felt that the pieces of sleeve were restricting the cables and removed them to give more flexibility.


The rest of the bare loom was fitted to the bike and I checked the length of cables. Thankfully none were too short and all appeared to be in the right place. A few had to be shortened. The main loom is fed up through the other, larger hole in the left side of the frame then up to the warning lights and instrument cluster.



The speedometer and rev counter have been fitted with earth tags.


A small link wire was made to join these to the earth return for the “lights on” warning lamp. I’ll include this when main loom is made up.


More soon!


Re-wiring, Part 3 (Switch loom) – 24 Nov 2015.

My next job was to produce the other small loom which is soldered to the handlebar lights and horn switch. I’m going to use the original chrome “snuffbox” switch which is in good condition without any melted contacts. The wiring is also in very good condition apart from one point where it looks like it has got trapped and cut the sleeving and the insulation of one of the wires inside. There was also a very perished rubber “T” piece in the loom. I hunted for ages trying to find a replacement and eventually came up with a nearly identical item at Disco Volante Moto here in Wales.

I removed the old sleeving and wiring terminals after checking that the wires were plenty long enough. The damaged insulation to the horn wire was repaired with heat-shrink sleeve.

I had planned out and drawn the alterations to the switch loom.

Switch loom

As I am adding relays to the headlamp circuits, the two wires (green and green/black) which originally went from the switch to the headlamp needed to be extended and diverted back toward the main loom. I don’t really like to solder joints in a loom as they restrict its flexibility. However, here I felt it was the best option because, if I were to unsolder then resolder the contacts at the switch, there’s a good chance of me damaging it.

Two new wires then need to be brought up from the main loom to the headlamp. As these have the same colour code as the originals, I added purple heat-shrink tags to them.

The earth return for the horn circuit was originally via the switch casing to its fixing screws, the switch-fixing screws to the clutch lever bracket, the clutch lever bracket to the handlebar, the handlebar to the fork stanchion, the fork stanchion to the headlamp bracket, the headlamp bracket to the headlamp shell, then the headlamp shell to the headlamp earth wire which is grounded to the rectifier bracket. A jumper wire is then needed as that bracket is mounted to the painted frame with rubber washers! I don’t think this is a reliable way of doing things.

However, improving this earth is difficult as there’s no way to put a soldered connection on the chrome switch casing. The best I could do was to add a wire with a tag to a fixing screw inside the switch.


A 3.5mm solder tag was nice and snug, requiring the screw to be wound through it but, is at best, optimistic as a long-term solution. I did test continuity between the switch case and the end of the cable with my meter. At the moment it’s very good.

I used “bullet” connectors on the headlamp wires. Plugs on the switch wires to the relays and sockets on the load wires from the relays to headlamp shell.


Re-wiring, Part 2 (Charging loom) – 23 Nov 2015.

I thought I would start with the easiest loom first. This is the one that links the alternator, rectifier and regulator. I had already decided I would use 2mm² cable for this.

First I dismantled the old loom with its oxidised wires, cracked insulation and dodgy terminals.



I decided to reuse the body of the three-way connector for the regulator and used a bit of stiff wire to release the terminals. I had bought some “with latches” ready. I also managed to find a replacement for the “long grommet” used where the cables exit the alternator housing. I’ve had this stashed for a while. I think I got it from somewhere in The States.

Copying the old loom was easy but, crimping the connectors was not! I’m still having problems with my damaged wrist and hand. My ratchet tool for uninsulated terminals needs more strength to use than the one for the insulated type and was flippin’ tough going. It was why I had to use those horrible red insulated things when I did some jobs on The Fire Bike a while back. Never mind. I persevered and slowly got the job done then went to soak my hand in cold water!




I added the extra wire as planned in case I upgrade to the later, more powerful alternator at some point – it’s the grey one wrapped in amalgamating tape at both ends. Replacement rotors for the original low-output alternator don’t seem to be available any more.

Re-wiring, Part 1 (Planning) – 22 Nov 2015.

As I said last time, I like wiring. I know that electrical work frightens a lot of people. Some of whom wouldn’t think twice about undertaking any sort of complicated mechanical job. As a child I liked making circuits with batteries, lights or buzzers and went on to wire model railway layouts, build radios, amplifiers and other small electronic projects. This is not my first total rewire.

I find it all very absorbing and I spend ages working everything out. I’ve held off posting anything here until now as I wanted to make sure that any diagrams would be right.

The first thing I did was to examine the various original wiring looms from the bike. These are;

  • The main loom. This runs from the instruments back to the fuse box under the seat. It possibly went all the way back to the tail light but, if it did, mine has been split.
  • A switch loom soldered to the lights and horn switch.
  • A charging loom linking the alternator, rectifier and regulator.

The last two are easy enough but the main loom is more complicated. Although original, my loom has been wrapped in insulating tape (by me) many years ago. Here is a composite photo of what I had.


I had labelled all the connections before removing it from the bike. Now I cut off all that horrible sticky insulating tape and kept the shape of the loom by holding it together with cable ties. I was expecting to find cracked insulation and dodgy connections and did. However there were some soldered joints and broken wires as well. Not my work.



Having done this, I was able to draw a diagram of the loom and then a schematic wiring diagram after consulting the one in my manual. As usual the colours didn’t quite match up. This is what I came up with. There are no direction indicators.

Original V7Sport wiring diagram

As it’s hard to see what’s going on in that photo, the same wiring diagram is here in pdf file format V7sport original wiring diagram and can be saved and printed as a four-A4-sheet-poster (2×2) if your printer can manage this sort of thing.

I am going to make some changes from the original.

  • Two relays will be used for the headlamp main and dip beams. This prevents the switch contacts from being melted and becoming unreliable. I don’t know if this used to happen with the original bulb but, it’s definitely a problem as soon as you upgrade to an H4 halogen. The modification also reduces the voltage drop at the headlamp giving the best light output.
  • I am going to use a later pre-engaged starter motor as fitted to bikes like the 850T3. These are gentler on the starter ring gear although they must weigh nearly double the original. This means a different wiring layout for the relay.
  • I shall also include an extra wire in the charging circuit between the alternator and rectifier which will remain disconnected. This is so that I can change to the later higher output type if I want. This needs the extra connection.
  • Finally, I’m going to run an earth return wire from the front of the engine block connecting the earth points together and finishing under the seat. This means I should not have to carefully scrape paint from frame fixings to get good earth return connections. It takes very little extra effort.

So this is my new schematic diagram.

Modified V7Sport wiring diagram

Once again this is available as a more readable pdf to download here Modified v7sport wiring diagram.

Wiring will be in 1mm² and 2mm² thin wall cable. The heavier type will be used mainly for the charging and ignition circuits. 1mm² will be ok for the rest.

I have got on with actually producing the new wiring so will be back with part 2 soon.

Slowly getting there – 5 Nov 2015.

I’m back again so soon.

Replacement tacho cable.

I’ve actually had this a little while. If you remember, I couldn’t get the cable I had bought previously to fit as it appeared to be too long. Luckily I was right in thinking this was the problem. As you can see, the difference in length isn’t much – 548 instead of 588mm.



The new cable has a small “kink” at the top but now I’m happy with how it fits.



Air filters.

I had taken the air filters off while I fiddled with something else – the breather box I think – so, I thought these might as well go back.


I temporarily hung the rear mudguard and tail light on with cable ties. This is for doing the wiring without the seat fitted. That’s actually everything on the bike apart from fuel tank, fuel lines, seat and wiring.



Wiring is next. I do like wiring!


Electrical components – 4 Nov 2015.

More progress with “Rhino” the V7Sport.

Over the past week I have fitted every bit of electrical equipment I could find to Rhino. This is without any actual wiring being done so that I can then build my own loom cable by cable.



The light unit will have to be changed. I really like the look of the old type of lamp with a “tripod” mounted bulb shield but, this unit dips the wrong way for UK roads and is for an old style bulb. I want a halogen unit. I’ll probably buy the same Wipac unit that I fitted to the “Fire Bike”.


Starter button.

The original has been fitted to the brake lever. It looks a bit rough.


Starter relay.

I removed the starter motor temporarily so that I could mount the relay bracket over the neutral switch on the gearbox.


The terminals on the relay had to be bent so that they would clear the solenoid on the starter motor.



Then I remembered that I don’t need this massive relay with the later starter motor I’ve fitted in place of the lightweight original. A smaller universal one will be enough. I’ll still be able to hide it up under the original rubber relay cover.

Regulator and rectifier.

These both mount on brackets which fit to the top frame rails and to the front of the frame above a cross tube.


The crimp on tag is just there to remind me which of the rectifier mounting screws is the earth.

In the next picture you can see that the front mounting bracket is offset. This is important because the mounting tabs on the rear bracket are the same width as those on the frame rails and both go to the right of the frame brackets – not both inside or both outside.



Ignition coils.

These are the original coils. They’ve been tested and appear to still be fine.


Each coil has similar mounting hardware.


One is mounted on a frame bracket down between the cylinders.


The other below the top frame rail.



The twin horns.

These are mounted to the front of the frame on sort of laminated brackets. Each horn is on three thin strips. The contacts on one horn are paired so that the other can be wired in parallel. You can just see the front mount for the regulator in this photo.


I run the wires round behind the frame bracket.


Under-seat light.

Yes, that’s right, the V7Sport has an under-seat light. This is designed to illuminate the fuse box when the seat is lifted. Less kind folks have said this is because of the less than reliable Guzzi electrics. The bike hasn’t had one during my ownership but, when I saw this reproduction, I thought “why not?” There were two holes in the right hand tool box to fit it to.


Fuse box.

I still have the very rare original fuse box which goes on the top of the rear mudguard’s fixed plastic section.


This fuse box has been the source of most of the electrical faults I’ve had in the past. Any others have been due to bad grounding (earthing) of components. Anyway, I have screwed it in place for now.

My choice is to dismantle and rebuild the fuse box completely or substitute something more modern. The original has the benefit of doubled terminals and internal links that make the wiring easy. The downside is that the fuses (the old ceramic type) and contacts get loose or corrode and cause bad connections. There are signs of melted plastic and once when I went over a particularly bad bump a fuse jumped out of its holder. As I write this the more I’m coming round to the idea of replacement in the interests of usability. I can always keep the original “in case”.