Replacing wiring?

For better or for worse I have bought a used wiring loom for my Convert. It is yet to arrive, but it is said to be good and complete - fingers crossed! Anyway my loom is a complete mess around the headlamp, indicators and switch gear. Wires have been cut, moved, joined and generally butchered.Where joined it is always to a different colour wire mainly due to foreign switches beeing added and as the Convert has lots of gizmos, many have been altered, cut or generally fiddled with over its lifetime. So, what I have are swiches fom something else, which are modified to fit and don’t work properly.Do I try and replace with Guzzi switches, if I can find them, or something like the Honda VT switches mentioned in the “wanted” section (V50)? As for the loom, is it easy to replace, or do I need to strip loads of bits off?Is it possible to replace the front section at a socket or some such so I don’t have to strip it all out? I hate electrics, and dodgy wiring is just making life even worse trying to track what’s what

On my T3 there is a block connector under the tank which would separate most of the rearward stuff from the front once disconnected.Your Convert may be the same.
I don’t mind looking at your electrics later in the year but I’m very busy at the moment and I don’t find sorting wiring something I can do in a hurried frame of mind. I do have an '81 convert with fairly unmolested electrics so I’ll take a look next time the tank is off.

Normski2012-10-07 20:55:03

I chickened out of the very job you are facing and called in a professional. Getting someone to build me a new loom was expensive but all the wires from the switchgear (Triumph T595) was stripped out and replaced with the colours that matched the loom making it all fit for purpose for the next 30 years.I did watch this being done and I learned that it isn’t impossible to do if you take your time but it helps if your good with a soldering iron! Try and determine what wires do what by testing the electrics and then draw your existing loom from that. Most of it will be obvious but some will need figuring out. You can always then fit the new loom section by section to keep it all manageable and bask in the satisfaction that you saved yourself a shed load of money!!

The Convert has some things on it unique to the Convert for instance the side stand cut out switch which is HUGE also there is a cut out switch in the clutch but the clutch can be replaced without said switch.

IF you are not good with electrics my advice is to get it sorted by someone who is. Personally I would NOT buy an old loom, the wires are by now getting corroded IE the copper wires will no doubt have gone black as well as old wiring is often dodgy.

To rebuild a loom with thinsulate wires is not that difficult,…get a large bit of chipboard, or ply wood

Lay the old loom onto it and mark the colours and where the wires go

Place pin nails in strategic places ie where wires T off

lay the new wires along and round the pins leave a fair bit of spare wire, NOTE the connectors

Wrap the loom with self amalgamating OR fabric tape OR buy the shrink sleeving

Fit it to the bike

Fit the correct terminals. Most lay people and some pro’s will leave a “gooseneck” of wire at the terminal end where possible allowing for a re termination

THIS takes some time and you will need to buy coloured cable, terminals good side cutters and good quality crimps as well as shrink fit sleeve

Look at polevolt or Towzatronics for the bits OR get someone who knows Guzzis like Towza to do it for you.

At this point you CAN use better items like

Sidestand switch
Clutch switch
Wire in fog/spots
indicators in mirrors
even keyless ignition
electronic ign

Ex Smoking Biker had his Spada re done by Towza and is very pleased with it

The newer cable is slimmer and far better than the old rubbish used as OEM back in the 70-80’s

There is no easy way around the 15 way multi block and other multi block connectors but you can make sure they are done as well as they can be.
guzzibear2012-10-07 21:27:35

What is a ball park figure for a professional job?

Luckily my wife doesn’t ever come on to this forum so I can tell you what it cost me. I used Ferret (see Classic Bike Ads section)as he comes to your house and does the work in your own garage. Besides the uprated switchgeaar I also wanted the fusebox replaced with a modern blade fuse one.The cost…£835 which is a lot of money but I had already decided I am keeping the bike for many years and it therefore made a good investment. Two years on I am really glad I did. The electrics have been completely reliable, with easier starting and brighter lights and frankly I no longer ‘worry’ when I make a long trip about whether it will make it and that feeling is priceless. BTW - bike is a 1980 LM2

took mine to towzer in Nottingham
total rewire not a original wire on the bike all done in the modern thin wiring
all new kawasaki switchgear
everythingwith high load on it supplied by a relay so switchs only carry control circuit load
cat one alarm supplied and fitted
no ignition switch all done off the remote and alarm circuit
acsessory socket -marine grade where the ignition switch was
all new resetable blade type thermal overload trips
all new led idiot lights and holders
nice little socket to plug in the towbar
Indicator mirrors wired in to circuit
done in 3 seperate harnesses
1 charging
2 main wiring
3 ignition
and fitting of the euro electric high output alternator supplied by me
cost me £850for the rewire switchgear and the cat one alarm

I am a person capable of the job , but no way could i get it so neat and tidy

well worth the profesional costs and i will be happy to show off the result and reccomend towsers services

ee54]What is a ball park figure for a professional job?[/QUOTE]

The only bike fusebox which has given me problems is the modern blade fusebox on my V1100 sport.
The 28 year old fusebox in my LM3 has been fine. I think all the fuses are origonal.
Having said that if the bike has had previous artfull bodger owners a complete rewire on a bike you intend to keep makes sense.

Agree with Baldini, I helped Eddie Cox put relays on his dads Spada lights. He now rewires Nuclear power stations at the drop of a hat.

Yes but Nucular power stations are most likley never seen italian wiring

I putta dis bit here and twist dese two bits together and presto, all issa fine. Trust me.
Ahhh, another grappa Luigi?
Luigi, Luigi, whay da rosary anda da white face wid der water running down?
Eet ees not so hot in here ees eet?iandunmore2012-10-09 10:46:14

I made my own loom on the bike, and then took it off and covered it with shrinkwrap. It was not a difficult task as I have a coloured wiring digram (there are links on this site) The other thing I did was a small sketch of each electrical component (relays, alternator, switches etc) showing the terminals, their numbers (if any) and the colour of the wire going to it. Now with the wiring diagram and the sketches I can take off any component and know how it is wired when it goes back.

The main reason for the rewire was to add relays to the headlights but when I started taking it all apart I found some previous botches. I was lucky that I had a load of coloured wire in small drums chucked in a skip on a site by the lift installers, so I could match the standard wire colours. For connectors I found a supplier of the original 15 pin type connectors and used those throughout, You can get 3 and 4 pin ones too. I put new connectors to the rear light so I could take the rear mudguard off, and also to the electronic ignition in one of the side tool boxes, these mods make taking the engine out easier.

I’m not an electrician, the biggest help for me though was an A3 coloured wiring diagram.Chris750s2012-10-09 10:53:41

Yes the A3 laminated wiring diagram with some non laminated ones you can write and draw on when working on an unfamilier system are priceless.

Just to add that if you do DIY, you must have good wire termination connections, either properly crimped or if in doubt, soldered.

I can fully understand the advantages of modern components and wiring and if money were no object, that is the way I would go. I don’t need half of the wires on my loom but identifying the ones I need and the ones I don’t is a pig because of the bodges.I just had a central heating oil delivery refused because they found a crack in the top of my tank, which now means a pretty hefty bill I’m sure!To be honest, I don’t know what to do now. I think I’m going to have to do the job myself, though I know it really needs a professional’s attention. It will be a case of undoing some of the worst mess and seeing if I can make it better, there are just so many wires that seem redundant now!

Print off a coloured wiring diagram at A3, if you can’t easily get that done, send me your address via PM and I’ll send you one. Next step is to identify what everything does. This will be made easier with the coloured wiring diagram, but you will also need a continuity tester, either a multi meter set to resistance (Ω ohms) or a battery and a bulb (or buzzer) so that when you complete a circuit the light comes on, this way you can work out what is connected to what. You could also use tape and biro to mark the wires until you are sure what is what. Mark any previous alterations from standard you find on your wiring diagram for future reference.


Once you have a good idea of where all the wires run, or don’t, you will be able to work out what is required and what is superfluous. Then you will be in a much better position to decide if the loom needs to be replaced or just tidied up, or if you need profesional help. In the past I have produced A3 coloured wiring digrams for friends using a photocopier, tipex, biro and coloured felt pens! Now I have a computer and it is a lot easier. One friend with a Z1 Kamakazi left his rebuild for a year as he could not work out the wiring, after I sorted him out a colour diagram, blown up from his Haynes manual, it was running in a couple of weeks. DIY is the cheapest way ahead, the components are not dear and the circuits are not complicated, the problem is working out what does what, colour helps millefold!

As to your tank, could not the crack in the top be covered with fibreglass, as it is the top I asume that the oil won’t leak out, but rainwater might get in. How about a ply and roofing felt cover/lid over the tank?

Good luckChris750s2012-10-09 15:16:50

Agree with most of above.
Work out how much the material would cost including minimum lengths of the different wire etc.
Then add 50% for errors etc.
Then see how close it is to £850.00.
I have rewired a bike once, in the army.
I was many times afterwards congratulated on having a complete set of vehicle wireing colours when most settled for half a dozen.
The army also generously supplied all the connectors etc, and my time.
It is not difficult but you need the tools, equipment and space.
It is very satisfying when you get it right.iandunmore2012-10-09 15:43:26

best bet think about what you have and break it down into groups
charging circuit
ignition circuit
everything else

on ebay ther is a seller kojaycat also at

he does basic colour laminated A3 wiring diagrams they are somtimes a basis for the range of bike but in the past i have found them decent enough to use he also does wire etc to whatever lenghth you need and even does a wiring kit with lots of different colours etc

Totally agree, having a coloured wiring diagram beside the coloured wires on the bike make it easy to see what is what.

They are available here for nought and are bike specific as Baldini has posted

All you need is an A3 colour printer, and I have one, and a laminater so buy me laods of beer and the whole club can have one! Chris750s2012-10-09 16:31:09

On the org bike there are 18 different colours to the wiring

You Can follow the org colours fairly easily which will make it easier to sort out at a later date

As I said get a large bit of cip board or plywood at least 6ft long and 4ft wide and place the loom you get onto it then figure out the spread of wires, a bit like a tree.

Mark the ends and colours carefully and from the diag figure out what they do.

Pit pins(thin nails) along the main spine length and at each branch and do a spread of pins where the individual wires all come out at the same place

Measure the length of wire protruding from any main loom

Work out either the sleeving you need or buy either the self amalgamating tape OR the fabric tape, available from classic car wiring places

Count how many and the type and size of the terminals and buy enough plus 5 spares…YOU WILL use them

Good crimping pliers and solder and soldering irons are a must

Take time using the spare loom you have ordered

ONCE you have figured out what you have got THEN work out any modifications ie different fuses/ relay block as opposed to the realays all over the place

If you get a relay BOX and to be fair smaller relays work out where they will go and THEN modify the new loom to suit the mods.

It is very very difficult to get around the headlamp connectors 15w and 12 w New ones with pins are available from Vehicle wiring products not difficult to do with a steady hand but will need soldering and I used silicone to seal the ends to save problems.

I BET you will find black wires under the insulation especially the wires going to the rear lights and indicators

At one time I did make looms for generator sets run by standing engines but the engine s were anything from HUGE Cummins or Rolls Royce to tiny 2 cyl listars…The principal is the same as they still had ign switch and instruments and all the things like oil pressuer water. other senders rev counter and instrument lights altenators etc IF I can help you I will be pleased to try.

I just did a quick search here are a couple of pointers

Just type in
“How to make a motorcycle wiring loom”