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Discussion Starter #1
Short history, Z50aK1
My bike came to me in bits, in a number of boxes, so now time to put the puzzle back together.

I want to 'buzz' out my harness, perform end to end wires continuity etc. This is an original harness that has been misbehaved upon. (see below) I will use a 6 volt lantern battery as a power source. I have pretty much aligned most as it should be on the bike. I separately checked the headlamp and taillamp and they light up as should. You chaps helped me re assemble my Hi Lo headlamp switch, it now works as should. I jumped the connector for the ignition switch. The switch unfortunately is MIA however I see these are readily available.
Background; I own old British cars so wiring issues are not daunting to me. I can crimp, join, solder, heat shrink etc.

Questions;
I will assume negative earth?
The frame of the bike of is the earth continuity?
Where can I buy correct gauge & colour wire? Male & female end terminals/bullets as well?

I am open to any & all advice for best way forward.

Thanks in advance

Bruce
 

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Never have been able to figure where to get the exact insulating covers for the female connectors, as they were something that was melted on, but the rest of the connectors that they sell are spot on. They also have the black sheathing for the engine wire harness, and the four plug connectors. You will want to buy the Molex crimpers. They are expensive but necessary to get the right factory style crimping. You need the 3.5 mm bullets :Vintage Connections - Motorcycle Terminals and Connectors - Vintage Connections
 

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Discussion Starter #3
Thanks for this davmo.

So these electrics are negative earth, right?

Not sure I understand "the black sheathing for the engine wire harness, and the four plug connectors. ".

The connector(s) for the ignition switch is in place as well as the one for the dynamo and the battery. Am I missing a harness for the motor? or is this as shown below?

B
 

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Yes, negative earth. Yes, that is the sheathing (should have called it the engine pigtail.) The plug replacement I was referring to is the one on the end of the engine pigtail and where it plugs into the harness. I think they may have the plug for the key switch as well.
 

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Why not just buy a new harness?
Old British cars? Screen name of Derrington? Any connection there?
 

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Discussion Starter #7 (Edited)
Great input all, greatly appreciated. 👍
My goal is originality where possible.
My harness as shown in my original post of this thread is quite complete and in good order. It needs some simple lovin' but nothing short lengths of proper wire and few terminals wouldn't cure.
The electrical kits shown appear to be all inclusive and a bit over the top for my needs, one little bike. I may just buy a small pack of bullets/female sockets etc. to complete what is missing on my harness.
I located a wiring schematic that matches what I have as a harness. I was able to buzz out the wires and find continuity where I think should be. :cool:
I will need to order up a key switch to verify functionality. Fortunately there is a parts outlet not far from me.

More questions;

1) Do the lights front & rear remain on when the electrics are powered up, either key on or engine running, (not my case right now)
2) Reading through some of the threads on this forum, I see mention of a 'kill' switch on these bikes. I do have one in my box of bits, however this appears to be aftermarket, or perhaps DIY? (below)
I don't see a provision of this kill switch on the schematic. Thoughts?

@ Gary s

1950's Jaguar, Riley, 1970 MG etc. One sports a Derrington cylinder head. No old British bike of Derrington fame in my garage unfortunately. Is this the connection we are looking for? Are you into old British mechanics? I owned an old Norton Atlas when I was a kid. I think I pushed that bike home more than I rode it. ;)

Thanks again in advance for the help provided and to come.

B
 

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1) No, lights (head, rear, instrument (AC)) come on after starting the engine. Neutral, brake light and blinkers are DC and powered by the battery.

2) On a standard monkey you kill the engine with the ignition switch.
 

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Make sure you buy the K1 version keyswitch...it's a one year only part.
There is NO kill switch for a K1...the keyswitch does that job.
Your K1...if it's the common US Z50A...will not have blinkers, neutral light etc.
The taillight and/or brake light MIGHT work with only a good battery installed...engine not running. I'm not sure about that tho. Maybe someone here knows.
 

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Discussion Starter #10
Kirrbby,
Thanks for this, I will bin the kill switch.
Yes, no blinkers, or instruments. A headlamp, a tail light and HiLo switch, simple rectifier and what I believe is switches on the brake cables and a straightforward harness.
I need to buy a correct battery but haven't got that far yet. I am verifying circuits continuity using a 6 volt camping lantern battery.
Presently I am trying to proof the wiring harness on the bench. So far I am feeling good that the harness is sound and I am following a correct wiring schematic.
I am aware of the 1 year only key switch from other discussions we have had here so pretty sure I am getting the correct one.

Thanks again

B
 

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Those ARE brake light switches in the cables. You should also have a high beam indicator light in the HL bucket.
Sounds like you are right on top of it all.
Get a sealed battery, instead of the leaker. You already have the wires for it.
 

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To add to the above, The key switch is a 3 position, with 1 being the off switch for ignition and lights, 2 is ignition and brake light circuit on without engine running, and 3 is everything on except for the HL, which only comes on with engine running. I have left the bike in second position before, where the brake circuit is active, and found the battery drained the next day because the lever was slightly depressed when it leaned against the wall. This particular year model is kind of cool in that it was the only US model that was configured like their big bikes, with a battery, rectifier, and brake lights, as well as a tail light that can be run off the battery, a safety feature.
 

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Derrington and old British iron- few here in the States would know what that even is. My very first bike is the 50 you see in my avatar but my second was a Triumph Tiger Cub. Like you I did alot of pushing - made me appreciate Hondas even more and have never owned another brand. Had bought a new 79 B back in the day and after 37 years just sold my MGA Coupe. Held on to the Derrington head though you never know..... +1 on kirrbbys battery recommendation they have a longer life and seem to hold a charge longer as well. If you don't use the lights you don't even need a battery- I found a new original battery,never filled it and removed the fuse,it's there just for the look. Good luck on your build.
 

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Discussion Starter #14
This is all very educational, and I really need that. :rolleyes:
@ kirrbby
I suppose the 'leaker' you mention is a lead acid battery? Is there another kind? gel? will it fit the battery holder of the K1?

@ davmo
I appreciate you explaining the key switch positions and functions of the lights. The headlamp was enigmatic until your explanation. I was working this out from the wiring schematic I have but you made it way simpler. 👍

I think and ask for confirmation.
The main electrical earth to the frame is through the key switch?

I have a switch in the post to me now so when it arrives all will be much clearer when I plug into the harness.

B
 

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No the key switch ground merely allows you ground the ignition to shut off the bike. Some of my friends favorite trick was to unplug the ignition switch and ride off. You'd try to tie wrap that plug so it sat between the frame and gas tank so it could not be reached so easily.
 

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This is all very educational, and I really need that. :rolleyes:
@ kirrbby
I suppose the 'leaker' you mention is a lead acid battery? Is there another kind? gel? will it fit the battery holder of the K1?

@ davmo
I appreciate you explaining the key switch positions and functions of the lights. The headlamp was enigmatic until your explanation. I was working this out from the wiring schematic I have but you made it way simpler. 👍

I think and ask for confirmation.
The main electrical earth to the frame is through the key switch?

I have a switch in the post to me now so when it arrives all will be much clearer when I plug into the harness.

B
The ground contacts are at the ends of the stator coils and at the key switch. The key switch ground has to be made through the frame, and is only good if the body of the switch is making good frame contact. The kill switch connects the ignition coil wire to frame, and it passes through the motor mount ears to the engine, grounding out the stator coils, killing the engine..
 

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Discussion Starter #17
Oh dear, and once again thanks for this.
I am missing an important element to this wiring circuitry?
Fair enough, I think I understand the engine earthing to stop it running. Sort of like my leaf blower, chainsaw etc.

How about the other auxiliaries, tail lamp shows an earth to the frame? (Through the fasteners?) the ignition coil shows an earth to frame? (Through the fasteners?) The AC generator shows an earth to the frame as well. Where does the Blue wire, (earth?) from the battery connect to the frame? I thought this is through the key switch?

B
 

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Oh dear, and once again thanks for this.
I am missing an important element to this wiring circuitry?
Fair enough, I think I understand the engine earthing to stop it running. Sort of like my leaf blower, chainsaw etc.

How about the other auxiliaries, tail lamp shows an earth to the frame? (Through the fasteners?) the ignition coil shows an earth to frame? (Through the fasteners?) The AC generator shows an earth to the frame as well. Where does the Blue wire, (earth?) from the battery connect to the frame? I thought this is through the key switch?

B
The lighting coil grounds through the rectifier, which is a frame ground through the mounting bracket. The ignition coil also grounds through the frame mounts. The tail light grounds through the frame as well.
 

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Discussion Starter #19
Hello davmo
I apologize for coming across as a bit thick ,
from the wiring schematic I see the earth points,. (snap below) I also do not see an earth at the rectifier as you suggest.

I guess I was expecting to see an earth from the battery to the frame, (mass) . I only ask and want to understand because as I mention in my original post, I am bench testing the circuits of the standalone harness. I can simply join a wire to these auxiliaries to establish a path for the earth.

B
 

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My bad, you are correct, no rectifier ground at the base (I was thinking of a floating coil with a full wave rectifier, just a brain fart.) since it’s just a half wave rectifier, that means the ground will be at the stater coil.
 
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