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1969 Honda CL70 Scrambler! My old dirt bike returns!

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  #1  
Unread 04-10-2011, 05:22 AM
Bob Bob is offline
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Default CL70 issue

Hey Smithers,

I have a 73 CL70. It has just in at the mechanics, and passed safety. However i am having an issue with it. When i ride the bike, and try to open up the throttle, the engine dies, but it runs at 1/2 throttle. When i turn on the signals, the engine dies, same with turning on the horn (the horn makes no sound). I make sure the battery is charged when i ride it, but when i am done riding, after 20-30 minutes, the battery is completely dead.

I feel it is an electrical issue. Any thoughts?

Also, the battery is grounded to the bike (ie the negative lead is directly connected to the metal frame of the bike), but i see in the wiring diagram the battery's negative terminal should be connected to a green wire. Will this cause a problem?
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  #2  
Unread 04-10-2011, 07:30 AM
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Hi Bob good to see another CL70 getting back on the road! Great bikes and everyone sees how useful they are and realizes they are valuable bikes.

The ground is definitely your biggest problem and needs to be corrected before any further troubleshooting. The ground from the battery typically goes straight into the wiring harness plug. This negative signal is grounded to the frame at the tail light and also the rectifier so it was not grounded to the frame at the battery compartment from Honda. They wanted to make sure the battery ground went to the rectifier first which requires a very strong signal -well as strong as a 6V battery can produce. The rectifier controls all the juice that the bike gets so you need to make sure that you find that wire that goes to the rectifier and connect it to the ground side of the battery. Or you can grab your own wire and find which terminal is the ground on the rectifier and connect that to the battery outside of the original harness. It's not a bad idea to connect the battery ground to the chassis but it's not necessary.

When I was young I noticed that when I cleaned up some of the connectors and soldered a couple connections that the electronics worked much better. So I just soldered everything together at that point... turn signals, horn, everything. People might say that's not good cause what if you have to replace something? Well I'll cut the wire and solder on a new one! But I've NEVER had to replace anything on the bike besides the battery (which I use connectors for the leads). And the bike runs awesome, starts easy and the lights are twice as bright and horn twice as loud as when I got the bike way back then.

Let us know how it goes. I'm sure the electrical signal is being degraded between the horn, lights and switch. But at least if you take care of the ground the rectifier can do it's job and the battery will charge and the engine should run better.
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Unread 04-10-2011, 08:32 AM
Bob Bob is offline
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Hello and thanks for the quick response.

I took my battery from charge, measured the charge at 6.20 V. Not fully charged, but i tried it out. I rewired the battery back to the green 4 way connector coming from the rectifier. I turned the key on, the head light took some of the battery charge down below 6 volts, started the bike up, and the battery continued to drop in voltage. ie, the bike is not charging the battery.

Do you have any thoughts? I have another complete parts bike, so if i need to change parts i can.
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Unread 04-10-2011, 09:19 AM
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You probably have a short somewhere. Look for discolored wires or feel around all the wires to see if any of them are warm/hot. These wires typically turn brown when they get really hot. You probably just have too much resistance in the whole system which is a result of corroded connectors all over the place. I can't see what kind of condition the bike or wiring harness is in so I can't say for sure. But you could just have a short somewhere which will drain the battery. Try taking off all the connectors from the rectifier and unbolting the unit itself and reconnecting everything making sure all the connections are free of corrosion and shiny. Check where the tail light connects and also the headlight. Maybe try disconnecting all of that since it's not crucial to the bike running. Since someone has connected the ground terminal to the frame with a wire they probably were trying to make it run because something else was wrong that they never fixed.

Then you have to resort to tracing every single wire in the harness looking for the cause/short. Some people have replaced the rectifiers with success but I have never seen one personally malfunction. I think they were successful because of a bad connection they replaced. You could also cut out all the connectors and solder all the wires together. Other than that replace the whole wiring harness.

I have never seen any component fail to cause an electrical symptom like you are describing. I think it's a connector problem or short which is caused by wired rubbing on the frame or rubbing against each other!

And last but not least you could also replace the battery completely with a brand new one since they are so cheap. If your battery is a little old I would probably just toss it and buy a new one. I have seen them sell for $15. Electronics are tricky. You just have to spend a lot of time looking things over really really closely.

Last but not least you could also have a problem with the ignition switch. It is a mechanical moving part that COULD potentially break. I would simply unplug the two wires and put them together and run the engine to see what happens. There are only two wires going to it and I just connect the wires myself on mine. Keep in mind you must unplug these wires when you part it (turning the switch off) so the battery won't drain from sitting there.

Last edited by Smithers; 04-17-2011 at 10:46 PM.
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Unread 04-10-2011, 10:39 AM
Bob Bob is offline
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Smithers

First thing first this week i will do is pick up a battery.

Electronics are not my strong point however. How do i check for a good ground if i use a multimeter?

Thanks again
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Unread 04-17-2011, 04:47 PM
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Default cl70

So my battery works after a recharge.

I can get it up to 50 mph based on the speedometer. however the battery is only at 4.5 V after about 15 minutes riding. any thoughts? this is after i charge it to 6.5 volts. no shorts that i can see
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Unread 04-17-2011, 10:48 PM
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So did you connect the ground wire like in the wiring diagrams or is it just connected to the frame?
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Unread 04-18-2011, 04:08 PM
Bob Bob is offline
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Here is what i have so far,

I can't find a short, the battery is still not charging off the bike. I grounded the battery back to the rectifier and still the same issue. I think that it is the alternator at this point as the rectifier seems good. I'll have to bring the bike in to a garage to get the alternator looked at.

to bad, as on a full charge the bike screams!

but 15 minutes later the battery is at 4.5 volts
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Unread 04-18-2011, 09:15 PM
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Damn I wish I could check it out in person for ya. Hmmmm.. checked the alternator coil wires? If they are pinched or have been in the past then there's a problem for you. I would hate for you to take it to someone and pay them to find some broken wire somewhere. : \
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Unread 05-19-2011, 08:28 AM
Bob Bob is offline
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Hey Smithers,

I have been thinking about something. Since i can't pinpoint the electrical problem, what is your opinion on swapping engines. I have a working cl70 engine in my basement on a complete cl70 same year etc...

let me know what you think.
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Unread 05-19-2011, 10:02 PM
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You have a complete and running 1970 model CL70? Or were you thinking of just swapping just the engine in and seeing it it's the engine or the harness that has the fault somewhere? It's a pretty quick swap that might just help you determine things faster. Not a bad idea.
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Unread 05-20-2011, 03:31 AM
Bob Bob is offline
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I'm going to do the swap today.

to answer your question, i have two CL70, both same year model. One i had repaired at a motorcycle place (currently on the road and having electrical issues) the other will be the bike that i'll take the engine from.

I'll let you know how it goes.
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  #13  
Unread 07-27-2011, 04:55 PM
Bob Bob is offline
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Default battery issue

Smithers,
Here is an update. I found an area were there was a short occurring. i seemed to have fixed it. Also the swapped engine is running really well. Over all, most of the time when i charge the battery, the charger immediately shows a full charge when i plug it in. I think that the problem has pretty much been solved. The bike has become my daily driver. cheap on gas and parking is free for motorcycles at work.

Thanks for the help
Bob
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Unread 07-27-2011, 08:02 PM
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Great to hear! Luckily these little guys don't have too many wires so all that is needed is some patience and a good flashlight to look things over carefully. Now go rack up some miles on that bike. I can't wait for the day I have some time to work on mine and fit some new street tires on it.

Ride safe try to keep the front end down.
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