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RT1 wiring question.

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Replied by MarkT on topic RT1 wiring question.

Here is the legend for the switch that should be original for your bike. Came from RT1b Rider's Manual in Tech Library. Yamaha literature can be what you'd probably call "a little dodgy" at times, so I will explain what does what.



OFF position

Connects the Black that connects to E or Earth to the Black (likely black/white in harness) that tees into the black or black/white wire from the points to the ignition coil. Grounding the points wire kills the spark.

Position I - Daytime running (before the "headlight always on" law was in place in the US)

The two blacks are no longer connected so you now have spark.

The Red (+ side of battery) connects to the Brown. Brown runs the battery powered accessories... horn, signals, brake light, (and hi-fi stereo system, if equipped.) :ROFLOL

The Green charging coil wire (daytime charge) from the stator is connected to the White which goes to the rectifier. Rectifier converts native AC power from stator to DC to be compatible with battery. This circuit charges the battery during the day.

Position II Night-time riding

The Red (+ side of battery) still connects to the Brown to power the battery-powered accessories AND you'll notice it also connects to a Blue (L). You must be a little careful here. This Blue goes directly to the taillight to power the taillight off the battery. Battery-powered taillamp became required by law in the US in about 1970 for safety. Previous to that, and in other regions of the world (Oceania for example), the taillight was powered from the engine on the headlight circuit.

The White to the rectifier is now connected to the Green/Red (nighttime charging coil) from the stator. This circuit charges the battery at a slightly higher rate with key in nighttime position.

Finally, the Yellow from the stator connects to the Blue/White. (I may be mistaken but I remember sometimes this wire is plain blue similar to how the ignition black/white is sometimes just black. On a standard harness you can't mix up the blues due to the connectors at the switch) Anyway, the Yellow from the stator powers the headlight and gauge illumination lights. Blue/White goes to handlebar switch. (There is no rectifier in this circuit so headlight circuit is AC power)

Looking at what you have, it doesn't seem to have the separate (battery) taillight circuit or the same battery charge circuits. I would get the correct switch.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
The following user(s) Liked this Post: Murf
19 Sep 2020 07:34 #31

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Replied by Murf on topic RT1 wiring question.

Many thanks Gr8uncleal, RT325, DEET, Swoop56 and MarkT. It is looking like I will have to locate the correct switch.

Berore I do that would anyone be able to answer the following question?

If white, green/red, blue/white, yellow and blue were all connected together in position II on the switch (I think I can acheive this with my current switch) would that work or not?

Many thanks, I really appreciate the help.
Last edit: 20 Sep 2020 02:26 by Murf. Reason: accuracy
20 Sep 2020 02:23 #32

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Replied by MarkT on topic RT1 wiring question.

OFF---- black----black/white blue/blue----blue/red
Position 1 red----brown blue----blue/red green----white
Position 2 red----brown blue----yellow----white----red/yellow----blue/red
Position 3 black----black/white blue----red----blue/red


Above, I've relabeled your legend to follow the Yamaha convention with regards to "position" to avoid confusion... I'm sure what you're asking is related to this relabeled legend?

My guess is you are thinking of not using blue/red at all (makes sense) and connecting the stator green/red to the switch red/yellow ?

The potential issue is that you would have two stator AC supply circuits connected directly together (green/red and yellow) which Yamaha never did as far as I know.

If you installed a Yamaha voltage regulator (following the factory service bulletin to the letter) you might be okay. Not sure though. Voltage regulator would be a good move no matter what. (Alan has probably already mentioned it)

Rather than connecting two AC power wires through the switch, I would be more inclined to bypass the ignition switch for the "battery charge" circuit. Connect either the green or green/red directly to the white bypassing the switch. Start with the green, if battery doesn't stay charged well enough when being ridden, swap to connecting the green/red to the white instead.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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20 Sep 2020 05:42 #33

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Replied by Murf on topic RT1 wiring question.

Many thanks MarkT. You are correct on what I had in mind and your version of it makes sense. I guess if I could find an European RT1 wiring diagram and parts list it would help but I haven't found one so far.
It is certainly looking like the best way is to find the correct ignition switch. Any ideas where I might find one or is it a case of looking on the bay?
20 Sep 2020 08:00 #34

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