1979 Ct90 Electrical Issues (1 Viewer)

[aarchie]

New owner of a 79 ct 90. I had one of these as a kid a 69, and had more fun riding than any bike I've been on since. Haven't ridden a bike in 15 years now, but was (and am still) looking forward to fun rides as an old kid now.

Headlight was reported as dead and needing replacement by seller. Was told electric was basically good. New battery is installed.

Before Purchase test drive notes:

Green neutral light did come on when ignition switch first turned on. Before starting, the brake light tested good as did turn signals.

Started easy enough. After brief warm up, drove about 1/4 mile before bike seemed to start "crapping out" losing will to run. Don't know if signals and brake lights were working during test drive.


Bike Died. Left me on side of road a few blocks from seller's place. He arrived and without getting out of his vehicle said "looks like you're not getting any juice" I guess it should have been a clue that (he knew) there was something wrong electrically other than needing a new headlight)

After a couple of minutes of effort, it started again, and it crippled the two blocks to where we started..

Anyway. Since the ride seemed to prove a solid engine with good torque, good shifting ability, good condition body... we purchased.

On arriving home I realized that the fuse was blown. Replaced it, and the bike immediately started. Started to check the lights and horn and bike died suddenly. Checked and found blown fuse again. oh oh.. Repeated process and blew second replacement fuse.

Tried some online self help first:

Downloaded manual and saw a test for rectifier - Thought this would be a good start - seeing all of the ct90 rectifier problem posts. However, it passed all continuity tests in book. (Note the rectifier does not appear to be the original. It's not the "orange" one seen in many photos online).

Since I plan to change the headlight to the DRATV offroad one, I don't know if I should install and replace all bulbs before looking for the problem. (it appears now that several bulbs in the headlight assembly are now blown - including the neutral bulb and turn signal that was working before).

I have looked at, but don't read / understand wiring diagrams, but have fantastic handle on following directions to the "T".. I have multi meter and can test IF i know specifically what I'm supposed to do. (ie - detach X from Y and attach positive lead to __ and negative to __ and take "ohm" "voltage" "etc" reading).

I'm looking for link or step by step fuse blowing troubleshooting process or guide that may help me locate where the electrical problem (or short) lies.

Thanks in advance for any tips on how to do this best (hopefully without blowing up too many bulbs or the off road headlight setup). Should I wait before installing "off road" headlight and new bulbs? Help please. Thanks in advance fior your tips.. It's greatly appreciated.

 

[lehiguy]

New owner of a 79 ct 90. I had one of these as a kid a 69, and had more fun riding than any bike I've been on since. Haven't ridden a bike in 15 years now, but was (and am still) looking forward to fun rides as an old kid now.

Headlight was reported as dead and needing replacement by seller. Was told electric was basically good. New battery is installed.

Before Purchase test drive notes:

Green neutral light did come on when ignition switch first turned on. Before starting, the brake light tested good as did turn signals.

Started easy enough. After brief warm up, drove about 1/4 mile before bike seemed to start "****ping out" losing will to run. Don't know if signals and brake lights were working during test drive.


Bike Died. Left me on side of road a few blocks from seller's place. He arrived and without getting out of his vehicle said "looks like you're not getting any juice" I guess it should have been a clue that (he knew) there was something wrong electrically other than needing a new headlight)

After a couple of minutes of effort, it started again, and it crippled the two blocks to where we started..

Anyway. Since the ride seemed to prove a solid engine with good torque, good shifting ability, good condition body... we purchased.

On arriving home I realized that the fuse was blown. Replaced it, and the bike immediately started. Started to check the lights and horn and bike died suddenly. Checked and found blown fuse again. oh oh.. Repeated process and blew second replacement fuse.

Tried some online self help first:

Downloaded manual and saw a test for rectifier - Thought this would be a good start - seeing all of the ct90 rectifier problem posts. However, it passed all continuity tests in book. (Note the rectifier does not appear to be the original. It's not the "orange" one seen in many photos online).

Since I plan to change the headlight to the DRATV offroad one, I don't know if I should install and replace all bulbs before looking for the problem. (it appears now that several bulbs in the headlight assembly are now blown - including the neutral bulb and turn signal that was working before).

I have looked at, but don't read / understand wiring diagrams, but have fantastic handle on following directions to the "T".. I have multi meter and can test IF i know specifically what I'm supposed to do. (ie - detach X from Y and attach positive lead to __ and negative to __ and take "ohm" "voltage" "etc" reading).

I'm looking for link or step by step fuse blowing troubleshooting process or guide that may help me locate where the electrical problem (or short) lies.

Thanks in advance for any tips on how to do this best (hopefully without blowing up too many bulbs or the off road headlight setup). Should I wait before installing "off road" headlight and new bulbs? Help please. Thanks in advance fior your tips.. It's greatly appreciated.

I happened upon you post by chance. I desert raced in the open expert class for quite a few years. The CT90 is at the opposite end of the dirt bike spectrum form the ones I keep around, but I happen to know some things about that bike. My father used to ride these a lot. He was forever replaceing the head light, seemed it would not run without that, or if it did, it didn't run for long. If my memory serves me at all, it believe that the headlight circuit forms a sort of quasi balast resistor. Go without and, well you already can see what happens then. Good luck.

 

[3jvj]

Start with a decent meter and a probe. You have a hot wire touching the frame. I would start wherever there appears to be issues (the headlight for example), or wherever it looks like someone has been.

I'd start by probing for continuity. Clip one lead to the frame, and start probing your positive wires. When one drops out to zero; you've found it.

I'd also start digging for a wiring schematic. It will be of some use. If I had one, I'd send it your way.

There might be some fellas here with more knowledge though.

Best of luck- Josh

 

[valentine]

Hey Archie,

Sounds like a short somewhere. I know there's lots of wires in the headlight bucket behind the headlight bulb. While you have the headlight out, I'd check those.

Have you joined the Yahoo group? There's a ton of info there. ct90 : World's biggest Honda CT-90/110 resource


There's also a CT90 forum with pretty good people. Honda Trail CT's Forums

 

[fledglingme]

buy a 5-10 pack of the same fuses. with a good one in the chamber, futz with the steering, switches, that last time blew youre fuse. when you blow the good one again, you'll know where to focus your efforts. i also love these bikes, but the cluster of wires that exit the handlebars, always seemed to me, to be a problem waiting to happen. don't buy parts thinking it'll magicly fix your problem untill you know what the problem is. i might add that the bike only has a 6volt system and headlights and other electrical things don't seem to work at the level one would think they should

 

[Tunnelratt]

Archie,
unfortunately these bikes have become as addictive to me as my FJ 40, problem is they are cheaper by the dozen, I have a handfull of them, two are 69's.
Blown fuses are are certain sign of a dead short, do as stated above with your meter, it will surface, 40 y/o bike, old wire, corossion you name it.

Two other things that really help these bikes out is a fully charged or brand new battery, if you dont have one or the other you will chase gremlins all over the place, also there is a trick we all do called a rectifier upgrade, its a replacement part that we get from Radio Shack, it makes all the difference in the world for the old electrical system.

Check out Dr. ATV for parts also the forums listed above, there is a ton of help out there, Great bunch of guys like the IH8MUD group.

Steve