Wiring help - '72 CL 450

Muddy4DSM

New Member
I'm kinda new around here but I'm working on a 1972 CL450 that's been sitting for about 2 years. Clean carbs, clean tank, new battery, fresh oil - for the most part, I think all the basics are there. I hooked up the battery last night, the headlight and front signals are working just fine(rear fender/lights are off the bike right now), as well as the horn and the starter button works.

As I pushed the starter button to get the bike running, the starter motor turns great - nice and solid but the motor's not sounding like it wants to start at all. My next step was to take off the headlight and see what's up with the wiring - check for anything loose, unplugged, whatever. Everything looked ok except for a couple little "jimmy-rigged" plugs I found...

1) The first one was a ground that comes from the right control through the headlight back to the rear brake switch. I found it on the diagram, no biggie (off ignition switch right in the middle of the page), and according to my Fluke meter it's continuous. What I didn't follow was that there was a red wire plugged into the connection between the 2 black wires that ran out the back of the headlight and was zip tied to the ignition switch section of the main harness. I have no idea what it's supposed to go to, why it would be there (can't find it on the diagram), but for some reason I'm thinking it's a makeshift ground that maybe works with the ignition coil or something leading to the not starting. It has a newer butt end connector on it so it's not factory. No idea on that one.

2) This is the other one that has me confused. Within the headlight there was a green/yellow wire TAPED to a brown wire. The brown wire looks like there's an end of it (on the diagram - right above the horn) that doesn't connect to anything so that's not a huge deal. The bigger question was the green and yellow wire that has to do with the front brake switch that's not attached to anything. Both wires had factory end connectors on them. Any idea where I can find the front brake switch and attempt to figure out where the other end of the green/yellow wire is if there even is one?

3) The last one I found which may be causing ignition problems is the green wire I found right near the condensers. I can't really find it on the diagram, but it appears to have an original factory wire plug on it but it ends about 2-3 inches outside of the harness. The diagram says it has something to do with the tail light, but I don't understand why it'd have a break in the wiring (from front of the bike to the back) right in the middle. I have a strange feeling that should be attached to something...

My last question may be a simple one and hopefully it will help pin point my electrical issue. Is there such a tool that has a light that hooks between the spark plug wire and the plug itself to let me know if there is a spark going through the wire? I looked through Autozone's website without much luck since I have no idea what it would be called. Has anyone seen these before? Know where to get them and/or how much they run?

I want to get this lil beast running before I take it apart, but I don't really want to take out the whole harness to figure this stuff out if I don't have to.

Thanks guys!

(wiring diagram attached)

CB-CL450(5speed).jpg
 

diesel450

"Fast with a past"
DTT BOTM WINNER
You can check for spark to the plugs by taking the plug out and then putting the cap back on the plug, then ground the threads of the plug to bare metal (the cylinder head will do, but not too close to the plug hole in case gas comes out) Then use the kick starter and turn the motor over, you should get nice blue spark arcing across the plug gap. If not then you have an issue. You can use a multimeter (volt meter) to test the wire cap if no spark. Check to be sure you have spark at the points first and that they are gapped and timed correctly. If you don't have a timing light you can rig up a static timing light with a 12 volt lamp and some test leads then follow the instructions in the clymer manual. I used the indicator lamp in the head light bucket and it worked fine.

Hope this helps,

Scott
 

Muddy4DSM

New Member
Well I tested the coil and condenser in accordance with one of my manuals (Clymer I believe) and I think I narrowed down the problem. The coil tested out fine, but when I tested the condenser it came back that it was shorted. Looks like that's the culprit for the no-start issue (at least for now). I'll pick one of them up off of ebay and then go from there.
 

Muddy4DSM

New Member
Muddy4DSM said:
Well I tested the coil and condenser in accordance with one of my manuals (Clymer I believe) and I think I narrowed down the problem. The coil tested out fine, but when I tested the condenser it came back that it was shorted. Looks like that's the culprit for the no-start issue (at least for now). I'll pick one of them up off of ebay and then go from there.

replaced the condenser and the points and still nothing... not really sure what direction to turn next :(
 

Flugtechnik

My bike is not transportation, it is a respite
I personally like the Glenns wiring diagram better, available here: http://www.oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class

3) Yes, there is a green (ground) wire that ends with a female plug near the condenser. It does not connect to anything. You can see it just above the "winker relay" in the Glenns diagram.

2) The front brake switch on a CL is in the Right hand control lever, in the hole right behind the brake cable. When you pull the lever, you should be able to see it in the crack that opens up. The wires are not bundled with the other ones from the RH control. It runs on the outside of the bars and into the headlight. #9 on the parts fiche.

HJ0906W0093035.gif


1) Don't know what that is. Black is hot, Green is ground. The PO may have added a wire for an accessory.

Check to see if you are getting a spark like diesel450 said. If your engine is painted, find some bare metal. Try it a couple times. You can use the starter instead of kicking it. If you try it in a couple spots and don't get a single spark, let us know and we can go from there.
 

Pettrit

New Member
I
Well I tested the coil and condenser in accordance with one of my manuals (Clymer I believe) and I think I narrowed down the problem. The coil tested out fine, but when I tested the condenser it came back that it was shorted. Looks like that's the culprit for the no-start issue (at least for now). I'll pick one of them up off of ebay and then go from there.
It's helped me :)
 

crazypj

Split personality, I fake being smart
Make sure points are gapped properly and also the insulating washers are in the correct places. Make sure wires are not shorted to ground at points plate or cover. Green with yellow tracer is usual on 'switched grounds' or alternator connector but I think the yellow trace was discontinued on later parts?
 

idahofrank

New Member
Seconded to what PJ said. In over twenty years as a MC mechanic (most during the "points" years) that was by far the most common reason for no spark.
 

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