Relay upgrades for '79 GS850G

[sarathchandars]

As I carefully extracted the existing wiring harness from my '79 GS850 I found that there are no relays barring the one for the starter motor (not counting the turn signals because it serves a different purpose). I'm planning to include relays for horns (I'm planning to install new hi-low pair), headlight (one relay for on-and off that power the headlight light and tail light on/off, and another for switching high-low beam) and replacing the starter relay solenoid with a more modern one variant.

I traced down to few options (I may change the brand/models but the ratings of the items below should be the same)
1. Horn pair: https://www.amazon.com/gp/product/B004Z0WGZS/ref=ox_sc_saved_title_9?smid=ATVPDKIKX0DER&psc=1
2. Headlight hi-low switch: https://www.amazon.com/gp/product/B004Z0WMHK/ref=ox_sc_saved_image_1?smid=ATVPDKIKX0DER&psc=
3. Headlight on/off: https://www.amazon.com/gp/product/B00BJLIB9G/ref=ox_sc_saved_image_2?smid=ATVPDKIKX0DER&psc=1 (this will be series with the relay above, so hi-low beam can work in conjunction with the on/off switch)
4. Starter relay: https://www.amazon.com/gp/product/B004Z0WMHK/ref=ox_sc_saved_title_1?smid=ATVPDKIKX0DER&psc=1 (the main circuit will get energized when ignition is on, so all lights and accessories can be on, but when the starter button is pressed, it will changeover to the starter circuit cutting off all lights; I'm looking for a 40A version and will use it if I get it)

Does anyone with experience modernizing the electrical of these bikes have any comment/advice on these?

Separately, I'm looking for avenues to overhaul the turn signal system as well. I found the note on bikecliff's website and found one for replacing the turn signal relay. But there is an aging control unit that I don't mind replacing if there are options to make it more modern. Any suggestions?

Thanks in advance!

 

[Nessism]

"Comment/advice on these"

Your bike will run to 100,000 miles in stock form with just standard maintenance. Adding relays is the answer to a problem that doesn't exist.

My opinion, before you go adding splices and cuts into your harness to add these relays, clean all the connectors, and refresh the harness in general. That will pay off in clean running, and make most of the mods you propose, unnecessary.

 

[sarathchandars]

Hi Ed. I value your advice! The unfortunate thing is that the turn signal is shot (I checked that all bulbs are fine) and the horns are missing, more worryingly there are no wires for the horns! Lastly the upgrade done by the previous owner for Dyna ignition has so many splices and just electrical tapes without connectors. Lastly, to examine the harness as per stock specifications, I took it out as carefully as I could, and found that few connectors are breaking off exposing the terminals. So it looks like I’m in for some reasonably extensive work so I thought I’d factor in some upgrades. I may not get to everything both because I may not have time or money or both, but preparing an inventory of everything.

this is before I get to the engine that smokes and smell like It’s burning oil.

 

[Burque73]

Hi Ed. I value your advice! The unfortunate thing is that the turn signal is shot (I checked that all bulbs are fine) and the horns are missing, more worryingly there are no wires for the horns! Lastly the upgrade done by the previous owner for Dyna ignition has so many splices and just electrical tapes without connectors. Lastly, to examine the harness as per stock specifications, I took it out as carefully as I could, and found that few connectors are breaking off exposing the terminals. So it looks like I’m in for some reasonably extensive work so I thought I’d factor in some upgrades. I may not get to everything both because I may not have time or money or both, but preparing an inventory of everything.

this is before I get to the engine that smokes and smell like It’s burning oil.

That sounds like a real mess. Would you like an unmolested harness? I have one from a '79 850. You may still wind up replacing some brittle or broken connectors, but at least the wire is all there.

 

[sarathchandars]

Hi Roger, very kind of you to offer. I'll still need to modify it "slightly" to support the Dyna ignition system. Does your harness have a turn signal system? If not, I will still have to (sort of) dig into the harness to make it work. The ideas that I had initially shared are actually relatively simple to implement with a modern blade fuse box. But the urgency depends on getting the turn signal system up and running... I haven't yet brought my multimeter out and stored the harness in a box. But once I get through the carbs and seal the airbox I'll get to the harness. Winter is coming

 

[Burque73]

No, I'm afraid the turn signal system is gone. I just have the main loom.

https://flic.kr/p/2qwtSzW

 

[salty_monk]

I ran basically the whole bike through a relay at one point... It's a bit of messing around but not hard to do & takes out most of the usual weak spots in an old loom.

 

[oldGSfan]

I gained 1.5V putting a coil relay in (but added a failure point). I may have accomplished the same by going through the whole path like Ed says (and he's probably right). But it works and the bike fires on the button better than any I've ever had.

Relay yeah!

 

[sarathchandars]

Thanks folks! This is encouraging. Over the weekend, I tinkered around a bit more and found more issues in the existing loom (I'm surprised there wasn't an inadvertent ground short!). Can any of you comment on the type and rating (not exactly the model may be) of the relays that I had suggested in the initial message?

I've seen that cycleterminal.com has interesting options. Any experience there?

Also, where can I get wiring? I don't trust Amazon for automotive stuff...

 

[850 Combat]

I got a 1979 GS850 for free once. I was planning on buying it, then the seller thought he blew it up, and gave it to me for for when he was moving. It turned out that it had a bad coil and ran on two cylinders. It had a couple extra quarts of oil in it too. I switched some coils wires around then it ran on the other two. The thing that got me about that bike was so much of the electrical was one year only. It had a totally different turn signal set up than other 850 and 1000Gs I had. Ignition, of course, and on and on. I could see doing some things different than factory on it. One of my 1000G, a 1981, PO had a modified harness for some anti theft stuff. He used single filament wire and crappy switches. I bought a used 1980 wiring harness and used that. It needed an upgrade for the running lights in front but that was pretty minor. The manual has a really clear section on routing the harness. I didn't look at it though. It would have been a bit better if I had. I do like to use soldered connections and shrink on stuff like that. I hope its better. Even on the stator wiring. If the stator fails, cutting and repairing those three wires is easy, and who hasn't seen overheated connectors between the stator and R/R? 1979 has separate Rectifier and Regulator, as I recall. I am in the habit of adding some redundant grounds too.

I would consider trying to source a 1980 or 1981 wiring harness and turn signal controller. Maybe 1982 or later, but those had a different frame. Maybe more slight differences. I have a little rack with small reels of suitable wire in various colors, but I don't recall where I bought it.

Good luck.

By the way, Nessism's knowledge and advice is always excellent. I find that on those fours, my personal preference for a rider is the CV carbs. The much easier throtlle pull is nice on long rides. I never thought I would say that.

 

[Who Dat?]

I don't trust Amazon for automotive stuff...

And yet, you are getting all your relays from Amazon?

 

[Grimly]

And yet, you are getting all your relays from Amazon?

Buy Bosch, if it can be ascertained to be genuine.
Heck, I go down to the local scrapyard and grab a few genuine Bosch from time to time, rather than put up with unreliable cheap tat.
So far, not had a used Bosch fail.

 

[sarathchandars]

And yet, you are getting all your relays from Amazon?

They were just ease of pulling out links. Surely not buying from there. I'll find auto parts suppliers who have these items in stock.

 

[sarathchandars]

Does anyone the rating of the starter motor relay? I don't know that the rating of the relay I'd suggested works because I don't have the baseline.

 

[Grimly]

Insofar as I know for most fours, starter solenoid about 80-100A max rating, but for big twins it might be twice that.
For example, car starter solenoids are typically dealing with 200A and upwards.
A lawn tractor solenoid is often used for an easy replacement on these bikes, so that gives you some idea of the range you need.

 

[sarathchandars]

That is super helpful, Dave. Clearly what I chose isn't going to work. So I'll be on the lookout for something of that rating. Rest of them seem relatively straightforward.

 

[dgates1]

Couldn't you just install a normally closed relay to the fuses that you want to turn off? Relay action fed from your starter button.

 

[sarathchandars]

Thanks Dave. I also received a response from ricks motorsports who make aftermarket start motors and on their dyne, their starter motor measured 0.75kW at 12.9V. Which means the relay would have to be at least 60A. While one can argue that the engine might not require all the power it is better safe than sorry and go for a relay that is beefier than my suggestion above. I thought the data might come in handy for others.

 

[dgates1]

Thanks Dave. I also received a response from ricks motorsports who make aftermarket start motors and on their dyne, their starter motor measured 0.75kW at 12.9V. Which means the relay would have to be at least 60A. While one can argue that the engine might not require all the power it is better safe than sorry and go for a relay that is beefier than my suggestion above. I thought the data might come in handy for others.

The starter already has a dedicated relay that connects directly to the battery. A new one is available for under $70.

Unless I'm missing the purpose of this relay you want for your starter?? You're just looking to disconnect other loads while pressing the starter button, right?

 

[Nessism]

The bike already has a starter relay. Don't add another into that circuit. Some people add a relay to feed voltage to the coils. That's, arguably, the only relay that will be beneficial.