Switch wiring

[Laverda Dave]

I am currently racking my brain with the 'unique' TL125s wiring.
There were no handlebar switches with the bike and the loom was unknown, it certainly isn't a TL for sure.
I have got quite far with the rewire but I now have two problems I cannot solve.
First one is the handlebar switches. TL parts are unobtainable so I have used a XL125 for the L/H side and a CL125 for the R/H side. Both switches mimic the originals but that's it. The issue is really with the R/H replacement switch which is basically an ON/Off lighting switch only (main/dip/indicator & horn is in the L/H switch. The R/H switch has four wires coming from it, yellow/white, blue/white (these appear to be connected with a moveable contact inside the switch. These also appear to contact in the OFF position. The other two colours are brown/white & Black. These are also linked with a moveable contact and operate in the ON position.
The problem is the Honda TL wiring diagram shows the correct TL R/H switch has 8 cables coming from it even though it serves the same function as the CL replacement switch I have fitted. The real problem I have is the Yellow/white and Yellow cables from the flywheel alternator are shown to feed into the TL R/H switch as two of the eight cables. The CL switch only has the Yellow/white cable so I therefore don't know how to wire the remaining Yellow cable from the alternator into the CK switch! Does anyone have any ideas of how I can wire the 'spare' yellow cable because it's obviously needed to supply power to the lights somehow?
The second issue concerns the Silicone diode rectifier. The TL wiring diagram shows it to be wired into the battery after the main fuse (but other diagrams show it to be wired in parallel with the battery so that's confusing as well!) on one leg (the positive side of the diode) with the negative leg going again to the R/H handlebar switch (and the CL switch doesn't have this cable either! Looking at the wiring diagram the yellow cable from the alternator appears to connect with the diode cable when the headlight is switched on.
Electrics really aren't my forte, any ideas welcome!

[BigAl (Alan)]

It's going tricky this one. Try having a look at the wiring diagram for the Honda MT125 (2-stroke)...similar set up to the XL125s but the diode is fitted very close to the battery.

[Bryanj]

What you have is a charging circuit rather like old Triumphs, i assume the TL is 6 volt,
What happens is that when you turn the lights on it connects extra coils in the generator to provide power for lights, if these were permanently switched in you would boil the battery.

If you cannot find a correct switch(450 twins had a similar switch) what you could do is fit a "clipper" diode and wire the generator for pemanent full power. The clipper shunts excess voltage to earth like the 650 British bike Zener but at 6 volt not 12

[Laverda Dave]

Thank you both for your replies.
I very nearly joined the two alternator wires together (yellow/white & yellow) after watching some YouTube videos (dangerous!), I'm glad I didn't now as Bryan states, I might well boil a brand new mottabatt🙁.
Thanks for the info about the MT125 wiring Al, having looked at it closely I think you've pointed me to the answer, put the yellow cable through the silicon diode rectifier. This will save using the clipper diode I hope.
I'll report back tomorrow once I get into the garage and removed the splinters from my fingers after scratching my head all day!
Cheers
Dave

[Bryanj]

This sort of genny does cause head scratching, i will try and simplify it a bit.

Usually 6 seperate coils wired as 3 pairs each pair joind in series so 2 wires out.
1 pair always connected to rectifier giving enough to run ignition.

The others not connected so nothing comming out.

When you turn lights on the switch also connects the extra coils to the system giving a bigger output to run lights.

This is the old Lucas idea, i think the Honda may only have 2 coils in there, 1 for low power then the 2 together for full power, it does make for a complicated switch!

[Laverda Dave]

Thank you both for your replies.
I very nearly joined the two alternator wires together (yellow/white & yellow) after watching some YouTube videos (dangerous!), I'm glad I didn't now as Bryan states, I might well boil a brand new mottabatt🙁.
Thanks for the info about the MT125 wiring Al, having looked at it closely I think you've pointed me to the answer, put the yellow cable through the silicon diode rectifier. This will save using the clipper diode I hope.
I'll report back tomorrow once I get into the garage and removed the splinters from my fingers after scratching my head all day!
Cheers
Dave

Thinking about this again overnight and your response this morning Bryan (yes, it is the two coil type alternator as you describe). My only concern is if I connect the spare yellow cable through the silicon diode rectifier and thus into the battery will this method then potentially boil the battery because the power has to go somewhere? I can't ground it to earth because the bike has lights and indicators erc.
I might be over complicating things, I'll report back once I get a chance to look at what I have later.
I should have paid more attention in physics at school!

[BigAl (Alan)]

There is normally 2 generator windings...1 rectified & 1 not.
The XL250s/500s uses a combined rec/reg for charging/clock lighting/indicators/ect
I have lifted the schematic from the XL500 shop manual, hope that you can see it

[Bryanj]

If its like the 500 its different from what i described, one coil charges the battery and works ignition then lights are on ac power

[Bryanj]

Dave if you have a scematic for both switches you can send me i will try and work out a way of using the switch you have to operate wires using relays for you, my email is in my profile but you should have it anyway

[Laverda Dave]

Thanks both, heading out to the cave now and will report back.
Cheers
Dave

[Laverda Dave]

Hi Bryan.
I've sent you a mail to your email address, can you let me know if you've received it please as I got a bounce back in my inbox it couldn't be sent yet it appears as sent in the outbox!

[Bryanj]

Nothing yet mate, did you use the .org.uk address?

[Laverda Dave]

Hi Bryan.
I resent it this morning to the .org address. No undeliverable mail message sent back so hopefully it's up in the clouds on its way to you👍.