Motorcycle Forum banner
1 - 12 of 12 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 ·
I have a 81 Honda CM400C and I’m having some issues. When I plug in the battery all the lights works and everything but when I push the ignition button nothing happens?
 

·
Premium Member
Joined
·
5,772 Posts
So, you don't even get a click sound from the starter relay when you push the button? If you do hear a click, the starter relay is bad, or the starter motor won't run. No click, and you will have to trace the wiring.

You should have a wiring diagram, or schematic, usually found in the service manual. The starter relay, or solenoid, needs power to switch the large battery cable to the starter motor, so there is a path from the battery and through the starter button switch and starter relay coil. In this path, there may be a safety switch, or two, to prevent cranking the motor if it is not safe to do so, like it is in gear. The diagram will show what, if any, safety switches there are, like a switch on the clutch lever, or a relay controlled by the neutral switch and side stand switch. My old CB450 has none of these, and the relay gets coil power directly from the battery; the other side of the coil goes directly to the starter button, which grounds the wire when pressed. Simple, easy to figure out. OTOH, my Suzuki Boulevard powered the starter button from the run/stop switch, which is powered from the ignition switch. From the starter button, it goes to a switch on the clutch, so the clutch lever has to be pulled in for it to go any further. From there, it goes to a relay, which is turned on if the bike is in neutral, or the side stand is up. From that relay, the power then goes to the starter relay to crank the engine. Way more complicated, so many more things to test.
 

·
Biker
Joined
·
1,624 Posts
So, you don't even get a click sound from the starter relay when you push the button? If you do hear a click, the starter relay is bad, or the starter motor won't run. No click, and you will have to trace the wiring.

You should have a wiring diagram, or schematic, usually found in the service manual. The starter relay, or solenoid, needs power to switch the large battery cable to the starter motor, so there is a path from the battery and through the starter button switch and starter relay coil. In this path, there may be a safety switch, or two, to prevent cranking the motor if it is not safe to do so, like it is in gear. The diagram will show what, if any, safety switches there are, like a switch on the clutch lever, or a relay controlled by the neutral switch and side stand switch. My old CB450 has none of these, and the relay gets coil power directly from the battery; the other side of the coil goes directly to the starter button, which grounds the wire when pressed. Simple, easy to figure out. OTOH, my Suzuki Boulevard powered the starter button from the run/stop switch, which is powered from the ignition switch. From the starter button, it goes to a switch on the clutch, so the clutch lever has to be pulled in for it to go any further. From there, it goes to a relay, which is turned on if the bike is in neutral, or the side stand is up. From that relay, the power then goes to the starter relay to crank the engine. Way more complicated, so many more things to test.

Kind of funny in a way. . . anyone who is even learning about riding is going to be told,
"The kix stand goes up make sure it is in neutral before you start it. want to REALLY be safe?
don't ride it. Any bike I ever rode had none of these things. I would say though that having
headlight come on when ignition is, is a very good idea.
 

·
Biker
Joined
·
1,624 Posts
I am thinking the neutral sw. is on the ground side of the relay coil, when tranny IS in neutral,
most likely the neutral indicator lamp is across relay coil as well. When relay coil is energized,
relay contacts complete circuit from clutch lever switch where power first went to after the
engine run switch was turned on.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #5 ·
I just replaced the solenoid because I just got this bike as a project bike. The original owner said it turned over but never started. Today I hooked in the new solenoid and tried it out. Would it be possible that the problem is that I'm using a lawnmower battery instead of a motorcycle battery because I could connect the starter motor straight to the battery and it would turn.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #6 ·
So, you don't even get a click sound from the starter relay when you push the button? If you do hear a click, the starter relay is bad, or the starter motor won't run. No click, and you will have to trace the wiring.

You should have a wiring diagram, or schematic, usually found in the service manual. The starter relay, or solenoid, needs power to switch the large battery cable to the starter motor, so there is a path from the battery and through the starter button switch and starter relay coil. In this path, there may be a safety switch, or two, to prevent cranking the motor if it is not safe to do so, like it is in gear. The diagram will show what, if any, safety switches there are, like a switch on the clutch lever, or a relay controlled by the neutral switch and side stand switch. My old CB450 has none of these, and the relay gets coil power directly from the battery; the other side of the coil goes directly to the starter button, which grounds the wire when pressed. Simple, easy to figure out. OTOH, my Suzuki Boulevard powered the starter button from the run/stop switch, which is powered from the ignition switch. From the starter button, it goes to a switch on the clutch, so the clutch lever has to be pulled in for it to go any further. From there, it goes to a relay, which is turned on if the bike is in neutral, or the side stand is up. From that relay, the power then goes to the starter relay to crank the engine. Way more complicated, so many more things to test.
I just replaced the solenoid because I just got this bike as a project bike. The original owner said it turned over but never started. Today I hooked in the new solenoid and tried it out. Would it be possible that the problem is that I'm using a lawnmower battery instead of a motorcycle battery because I could connect the starter motor straight to the battery and it would turn.
 

·
Premium Member
Joined
·
5,772 Posts
I just replaced the solenoid because I just got this bike as a project bike. The original owner said it turned over but never started. Today I hooked in the new solenoid and tried it out. Would it be possible that the problem is that I'm using a lawnmower battery instead of a motorcycle battery because I could connect the starter motor straight to the battery and it would turn.
So, no click of the new part? Or, does it click once, but not run the starter motor? If there is no click, you need to go over the wiring, to find out why.

A lawnmower battery should be able to click the solenoid, even if it is not strong enough to run the starter motor; the lights would dim or go out if that is the case. Since it is capable of cranking the engine, it should, even if it won't start, when you press the starter button. Cranking but no start is one effect of a battery that is too weak, because the Voltage drops too low while cranking to generate spark.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #8 ·
So, no click of the new part? Or, does it click once, but not run the starter motor? If there is no click, you need to go over the wiring, to find out why.

A lawnmower battery should be able to click the solenoid, even if it is not strong enough to run the starter motor; the lights would dim or go out if that is the case. Since it is capable of cranking the engine, it should, even if it won't start, when you press the starter button. Cranking but no start is one effect of a battery that is too weak, because the Voltage drops too low while cranking to generate spark.
Yea there is no click and there is no spark. I haven't checked the fuses yet though, would that cause a problem?
 

·
Premium Member
Joined
·
5,772 Posts
Yea there is no click and there is no spark. I haven't checked the fuses yet though, would that cause a problem?
Got a Voltmeter? The solenoid has four terminals: two large ones, and two small. In my '70, one of the small terminals is connected to the key switch, and will show battery Voltage when the key is on, as does the other small terminal until the starter button is pressed to ground it. Later models had the starter button powered from the run/stop switch, and the other terminal of the solenoid connected to ground. In this configuration, there would be Voltage on one of the small terminals only when the starter button is pressed (key on, of course). The run/stop switch would get its power through a fuse; in the 450, there is only one fuse, but newer Hondas have a few more, with one for the ignition and starter circuits.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #10 ·
Got a Voltmeter? The solenoid has four terminals: two large ones, and two small. In my '70, one of the small terminals is connected to the key switch, and will show battery Voltage when the key is on, as does the other small terminal until the starter button is pressed to ground it. Later models had the starter button powered from the run/stop switch, and the other terminal of the solenoid connected to ground. In this configuration, there would be Voltage on one of the small terminals only when the starter button is pressed (key on, of course). The run/stop switch would get its power through a fuse; in the 450, there is only one fuse, but newer Hondas have a few more, with one for the ignition and starter circuits.
I'll try the voltmeter test and yea there are 3 fuse's and one is leading to the starter button and also to the solenoid.
 

·
Premium Member
Joined
·
5,772 Posts
I'll try the voltmeter test and yea there are 3 fuse's and one is leading to the starter button and also to the solenoid.
I found a few wiring diagrams for the 400 with electric start, and they show the neutral and clutch lever safety switches, as well as a fuse for the starter button. The clearest one shows the solenoid is either grounded by the clutch lever switch, or the neutral light switch through a rectifier (diode). So, if the neutral light is on, or you pull the clutch lever in, it should crank, provided the fuse is good.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #12 ·
I found a few wiring diagrams for the 400 with electric start, and they show the neutral and clutch lever safety switches, as well as a fuse for the starter button. The clearest one shows the solenoid is either grounded by the clutch lever switch or the neutral light switch through a rectifier (diode). So, if the neutral light is on, or you pull the clutch lever in, it should crank, provided the fuse is good.
I actually didn't try that, surprisingly
 
1 - 12 of 12 Posts
Top