Your motorcycles and mine

rsv1cox wrote:You sure put that Suzuki over the road Tee Bee, I love the Yukon picture and the mudder.  Wish I still had my first Honda S-90 George, then I would probably not be going through this.  Hard part is done though, mostly cleaned up waiting for a wiring harness and reassembly.

Bob, hindsight is always 20-20. There are a lot of things I still wish I had but don't.

rsv1cox wrote:The S-90 is just parts.  The PO had hacked the wiring harness to bits.  I will have to replace the whole thing.  Anyone know what this part is fed by the red, yellow and pink wires?  A first I thought it was the rectifier but it's not.  It's hard mounted to the frame under the seat.



Mark had the right idea, ensure that it runs first then restore.  I took the opposite approach. Bob

Bob, you've got a collectible, and as such, the approach you are doing of being totally committed means you'd see it through the end regardless, no?

Hondas seem to be very consistent on their wiring, or so I've gathered. Here is the wiring diagram for the early CL70 motorcycle / scooter:

George's Google Share Drive: CL70 Wiring Diagram (GIF file)

According to it and my intuition, it is the solid state silicon bridge rectifier. Some time in the late 1960's, they started coming out with silicon diodes to replace the seleniums. It could be that what you see is a newer part in silicon that superseded the older 1950's selenium.

My 1971 CB100 had an orange finned larger selenium bridge rectifier. Back in 1980 as a college student, that rectifier lost a diode in the bridge. Factory part for a college student was too expensive. I did a little research, replaced it with a 50 PIV (peak inverse voltage, i.e. the break down - failure starting max voltage), 25 Amp silicon bridge rectifier from Radio Shack for under $6 or so. I snipped the wiring off the selenium rectifier assembly, soldered the wiring harness to the new silicon rectifier. Drilled out the 2" long mounting stud for the old rectifier. Then put a bolt through the center hole of the new rectifier, and mounted it to that tang under the seat. That tang also acted as a heat sink for the new rectifier.

Radio Shack still has the 50 PIV 25 Amp bridge rectifier for $2.84 if you can still find an open Radio Shack (or order on line):

https://www.radioshack.com/products/50v-bridge-rectifier

Fired up the bike, voilà! Now the bike alternator was charging the battery. The only regulator on these simple 6 volt systems in the internal resistance of the wet cell battery. Talking about the stability of silicon, my CB100 still uses that silicon bridge rectifier 35 years later, good stuff.

Oh, and a WARNING! Never run the bike engine with the battery out of the circuit. Without it, the alternator puts out enough voltage to blow the rectifier assembly, light bulbs, ignition coil and capacitor.

Here's a link to a lot of old Honda wiring diagrams, free download:

http://www.classiccycles.org/1852/597922.html

You might find a wiring diagram close enough to suit. These single cylinder small bikes had a very simple electrical system. Can't say specifically, but you may be able to adapt a new aftermarket retro wiring harness from another model to suit yours. There is a bike shop in Thailand that has an S90 wiring harness for $17.90 + $15.00 shipping to US. I don't vouch for its genuineness, you'll have to look it over and decide.

http://www.ebay.com/itm/LG269-HONDA-CS90-S90-CL90-MAIN-HARNESS-WIRING-CA-/262290213045



For my CB100, I've ordered a number of parts both locally from where I could, overseas from Hong Kong and Singapore. In the Far East they still keep these old bikes running. For it and my former 1987 Suzuki LS650 Savage, ordered some NOS parts place in Netherlands:

https://www.cmsnl.com/

Got a few odd ball electrical parts from a small motorcycle / scooter parts outlet: dratv.com Beatrice Cycle