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Discussion Starter #1 (Edited)
Stripping down my new-to-me 1973 TR7RV in preparation for a rebuild. Good news, I found the frame numbers and they match! Anyway, a few minor questions so far, before I get into the serious work of

How could I tell if the frame has original paint? It's been in someone's garage for 29 years and he didn't paint it. Needs some touch-ups, so if not original I'll paint. If it is, I'll do a few touch-ups and leave it alone.

Are there supposed to be large welds on the hoop under the seat, about a quarter of the distance from the main frame? Looks like someone cut it and then changed their mind to me, but maybe it came that way.

Wanted to test the electrics and decide on a new loom. Which brings me to, positive grounded to the frame? Really? Right-hand shift, powered frame, opposite day in the Triumph design shop I guess. I was wondering why the PO had so thoroughly taped up the frame ground. Don't get me wrong, I dig it. Anyway, mine came without the negative end and fuse. What inline fuse amprage is recommended? Also, assuming it works, is it ok to repaint the rectifier, since it's flaking pretty good?
 

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The weld blobs should not be there. Thats a classic place for amateur "bobbing" of the frame. Mine was completely cut off just behind the shock mounts...
Yes these bikes are positive earth and none the worse for it.
If the frame had been powder coated you could tell, the frame number would be hard to read for one thing. 20A fuse should be plenty, some people run less. I think the standard was 25A. Keep the fuse rating as low as you can.
 

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I would replace the standard fuse holder with one of the blade type ones as used on modern bikes and cars.
If I were you I would also run a solid state regulator rectifier, electronic ignition ( I prefer Wassell) and a single coil with dual output.
That's my personal preference and others will prefer original points.. Also the electrical components on mine were so beaten up I thought I might as well replace the lot.
by the time you have finished you will know your electrical system inside out!
 

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Discussion Starter #4
Thanks. It does look like a reversed bob job, but been there awhile. I'll grind them down while I'm at it. I'm not worried about positive earth, just bemused. I prefer to run points and leave the original electricals alone if I have a decent charging voltage with the headlight on. It'll be awhile before I can check that though.

Update, I found the other end of the fuse holder, which is also red. Hmm, two red wires on the battery :). I will try a 20A and see if I get any magic smoke.
 

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In the early days of electrical systems, positive earth was pretty much the norm in europe (well the UK at least) and not just on motorcycles. Alleged to be due to the electrolytic effect on the brass radiators of the time but that may just be a myth.
As for right hand gear change, this derives from the early handchange gearboxes. Most people are right handed so it was easier to change gear with your right hand, especially with the rudamentry clutches of the time. When foot change came in the foot mechanism just stated on that side. It was only with the Japanese that lefthand foot change became std.
 

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Discussion Starter #6
In the early days of electrical systems, positive earth was pretty much the norm in europe (well the UK at least) and not just on motorcycles. Alleged to be due to the electrolytic effect on the brass radiators of the time but that may just be a myth.
As for right hand gear change, this derives from the early handchange gearboxes. Most people are right handed so it was easier to change gear with your right hand, especially with the rudamentry clutches of the time. When foot change came in the foot mechanism just stated on that side. It was only with the Japanese that lefthand foot change became std.
Thanks for the info. I'm idiosyncratic (or just idiot) enough to be thoroughly entertained by the differences from the norm. If nothing else it'll make stealing the bike that much tougher.

I blew the fuse immediately, as I mostly expected I would. Lots of cool fall nights ahead for continuity testing. I quit wasting time and started on the engine. Oil drained and fasteners soaking up PB Blaster overnight, watching Plewsy/Lunmad videos to pass the time.
 

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I blew the fuse immediately, as I mostly expected I would. Lots of cool fall nights ahead for continuity testing. I quit wasting time and started on the engine.
Not a good sign.Are you sure you connected the +VE terminal to the red ground wires?The best place for a fuse is also at the ground side of the battery.
 

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Even Harley Davidson had right side shifters. Early Sportsters are an example.
If you have 2 red wires to the battery it's been bodged! I'd recommend a new harness.
You can keep the points if you like but I'd still go with a solid state Regulator/Rectifier.
 

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Discussion Starter #9
Not a good sign.Are you sure you connected the +VE terminal to the red ground wires?The best place for a fuse is also at the ground side of the battery.
I'm certain, though the fuse is on the negative side, which appears to match the wiring diagram.

It's been bodged for sure. Will look into a solid state r/r and a new loom today as well, probably simpler to replace it entirely than undo all the crimps and tape on it.
 

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Originally the fuse was on the -VE side of the battery,but there are advantages if you fit it to the +VE side.

If the fuse blew immediately,suspect a blown zener diode which has become short-circuit.Disconnect the wire from the zener (at timing-side air-filter case),and the short-circuit may go away.You could safely start up if you have points ignition,but the voltage will get high when you rev the engine.At 3000 rpm it would be safe if the headlight is turned on.

A rectifier/regulator may be cheaper than a new zener.
 

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Discussion Starter #11
Originally the fuse was on the -VE side of the battery,but there are advantages if you fit it to the +VE side.

If the fuse blew immediately,suspect a blown zener diode which has become short-circuit.Disconnect the wire from the zener (at timing-side air-filter case),and the short-circuit may go away.You could safely start up if you have points ignition,but the voltage will get high when you rev the engine.At 3000 rpm it would be safe if the headlight is turned on.

A rectifier/regulator may be cheaper than a new zener.
I don't see anything resembling the pictures I got when I googled zener diode. Clearly I have a lot to learn here, will apply myself before asking further questions.
 

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The zener is normally on the filter case,just in front of the battery.Look for a large brown/blue wire with a big female spade terminal.
If you already have a rectifier/regulator fitted,the zener is probably removed and the wire taped up.The stator wires from the primary case would lead to the new rectifier/regulator box,instead of the old rectifier.

If you have a rectifier/regulator,check the polarity.The red wire from it will be grounded,if the bike is still +VE ground.
Some owners,in their "wisdom",wire these regulators -VE ground.It can cause confusion and damage if the colour codes in the harness remain unchanged,because red is commonly accepted as +VE.

Electrons flow from the -VE terminal through a circuit to the +VE terminal.The frame is not normally termed "live",regardless of its polarity.It does become a part of the ignition circuit,as does the battery.It's not a part of any lighting circuit,or hopefully,any charging circuit.There are dedicated ground wires to handle that,and the frame is not a necessary part of the circuit.
 
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