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Motorcycle Repair/1973 honda cb450 k5 rectifier


Hi Bill, I noticed when re-installing my electrical components and wiring harnesses that the green wire's insuation on my rectifier is nearly melted completely through along it's length. Seems I've read somewhere (probably on the vjmc forum) that these rectifiers have been a common problem over the years. It consists of a green, red/white, pink, and yellow wires, if that's any help. Would you reccomend a aftermarket modern rect/reg replacement? Or what would be the best solution? This is a refurbishing project not a restoration. Thanks.

Steve, for the most part the charging system components work well on a stock bike. The original selenium rectifiers can be fragile and die with age, over charging or running a bike with a dead/dying battery. Also the current regulator needs to be working properly.

The new solid-state reg/rectifiers are generally a bit more reliable, if purchased from a known company.

If the little harness ground wire isn't attached to the battery ground cable at the battery, the ground system is unbalanced and may have caused the overheating of the wire. Ground lead inside the main harness ties into the turn signal units and voltage/current regulator. When you open up one leg of it, then the current backs up to the next available ground connection, which overheats the wiring.

Bill Silver  

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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