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Honda CB700SC Nighthawk S: Won't start

Definitely put the battery on a charger and see if it will hold a good charge, if not replace it. As far as finding your electrical issue, if I were you I would hold off on trying to diagnose any problems until you get the new harness in there. Who knows, just replacing the harness could solve whatever electrical issues you're having. If you're still having issues with then new harness in then dive into troubleshooting. Good luck!
 
The harness came in today!
I'm planning on trying the charged battery possibly on Saturday but the harness transplant won't be for a while with school and all.
I'M SUPER EXCITED! :loco
 
I'm having doubts

I've been staring at the harness for a while and I realized that the part my uncle hacked up might not even be a part of the harness.... so that makes me think about if it's the switch assembly that might have the short. Also, the harness came with ANOTHER Silicon Rectifier. :laughing

Maybe I should have another crack at opening the left switch to check for shorts there first before I replace the harness. :nchantr

But I'll see after I try the zombie battery. :deadhorse
 
Just because battery is not at optimal charge is not causing your fundamental problem.
So although you may ultimately need it, it is not going to further your cause in solving the issue.

If that green wire is getting hot, then positive voltage is being applied directly to it (or at least the Green/Red).

So the battery polarity was correct?
If you disconnect the green/red from solenoid, do you have the problem?
If you disconnect the Rectifier do you have the problem?
 
D'Ecosse said:
Just because battery is not at optimal charge is not causing your fundamental problem.
So although you may ultimately need it, it is not going to further your cause in solving the issue.

If that green wire is getting hot, then positive voltage is being applied directly to it (or at least the Green/Red).

So the battery polarity was correct?
If you disconnect the green/red from solenoid, do you have the problem?
If you disconnect the Rectifier do you have the problem?
Click to expand...

Understood about the battery.
I came back to it with the tinder disconnected(the shop owner noticed that the lights on the instruments were on, I must have forgotten to un-clip a connector) and the voltage at 11.7V
Wasn't sure if it was dead but removed the battery and reconnected the tinder for when I return again.

1. Polarity was correct.
2. I ran out of time so I couldn't try the the red/green wire ( plus, the battery was dead)
3. From what I remember, the problem persisted with the rectifier disconnected. Not 100%, if that was the case. What's the reason why that would make a difference? I'm curious.

Thanks for the input!

I'm going to try troubleshooting after replacing the harness when I have more time to dedicate removing all the bits of the bike. :teeth:ride
 
Progess!

HupJai said:
Understood about the battery.
I came back to it with the tinder disconnected(the shop owner noticed that the lights on the instruments were on, I must have forgotten to un-clip a connector) and the voltage at 11.7V
Wasn't sure if it was dead but removed the battery and reconnected the tinder for when I return again.

1. Polarity was correct.
2. I ran out of time so I couldn't try the the red/green wire ( plus, the battery was dead)
3. From what I remember, the problem persisted with the rectifier disconnected. Not 100%, if that was the case. What's the reason why that would make a difference? I'm curious.

Thanks for the input!

I'm going to try troubleshooting after replacing the harness when I have more time to dedicate removing all the bits of the bike. :teeth:ride
Click to expand...

I finally got a couple hours to work on the Nighthawk! :ride
Battery holds a charge, installed it with the correct polarity, held the the starter button down, and bypassed the solenoid with a screwdriver.

IT STARTS! :teeth

The clutch wire (green & green/red) insulation has partially melted off the conductor. I'm going to disassemble and solder on new cables. Or should I just buy a new switch?

While the bike was running, I decided to try out the Green/Red to Green connection. I thought maybe the short was in the switch side. Nope. The fuse blew. Regardless of the ignition position on "OFF" or "ON". but I THINK it's okay when I disconnect the rectifier. Engine starts up with and without the rectifier. So this is getting interesting, right? :wtf

I thought maybe it would be a good time to swap out the old harness. SO I unplugged everything but the rear lights and plugged everything into the new harness. No change in the symptoms.

Did I mention that I have to keep my thumb down on the starter button to keep it running?
Or that the engine starts and stays on regardless of the ignition position?
Oh, to top that off, there's a little whirring noise coming out of the case.

Tomorrow I'll clean/inspect the insides of the right switches, check the ignition switch and re-solder the left switch back onto the harness. My guess is that the harness is alright and that the left switches are okay.

Thoughts?
I could just carry a screw driver on me and never let go of the switch all the way down to SJ from SF. :teeth
 
HupJai said:
Did I mention that I have to keep my thumb down on the starter button to keep it running?
Or that the engine starts and stays on regardless of the ignition position?
Oh, to top that off, there's a little whirring noise coming out of the case.

Thoughts?
I could just carry a screw driver on me and never let go of the switch all the way down to SJ from SF. :teeth
Click to expand...

Glad you're making progress. Electrical is fun, like a puzzle where you have to make your own missing pieces.

Most times, jumping the contacts on a solenoid/starter relay will turn the starter by itself. Shouldn't care whether you're hitting the starter button. The starter button's job is activating the starter relay, which the screwdriver is doing instead. Maybe it does other cool stuff on Nighthawks though, I'm too lazy to look up a wiring diagram.

At a guess, I'd say the whirring noise coming from the case could be your starter continuing to spin, because you're continuing to hold the starter button and the screwdriver. Neither of those things should be needed to keep the bike running, and they're definitely not good for the starter or starter relay. Plus all the current drawn by the starter can do funny things to your bike's electronics.
 
bcv_west said:
Glad you're making progress. Electrical is fun, like a puzzle where you have to make your own missing pieces.

Most times, jumping the contacts on a solenoid/starter relay will turn the starter by itself. Shouldn't care whether you're hitting the starter button. The starter button's job is activating the starter relay, which the screwdriver is doing instead. Maybe it does other cool stuff on Nighthawks though, I'm too lazy to look up a wiring diagram.

At a guess, I'd say the whirring noise coming from the case could be your starter continuing to spin, because you're continuing to hold the starter button and the screwdriver. Neither of those things should be needed to keep the bike running, and they're definitely not good for the starter or starter relay. Plus all the current drawn by the starter can do funny things to your bike's electronics.
Click to expand...

AHA! Makes sense. :cool

The screwdriver is only touching the contacts as the engine cranks. After I get the engine going it doesn't need to stay in place. Sorry for the confusion!

Also, it whirring noise does not stay, I actually only notice it when the ignition is "ON" for a shirt period.... I think. :teeth

Also, for everyone's convenience (and my benefit), wiring diagram is the last attached photo on post #1! :D
 
If the green & green/red wires still get hot on the new harness and is not connected to the hacked harness, would that mean that another component is the blame? So maybe I shouldn't be looking for a short but a faultily part. From the diagram, it looks like the starter button is connected to a bunch of things. When I push the starter button, the Yellow/Red and Red wire are connected but the green (what I'm thinking is the solenoid wire) and yellow contact points don't connect. Am I missing something here? I tried to put a load on the Re/Green & Green wires so the fuses would some popping(I'm running out). But the short and load still don't get the starter button to get the solenoid to work. The solenoid is supposedly new but I can't get the thing to work. Any thoughts would be greatly appreciated. :ride
 
I am thinking that what you are trying to do is probably one of the most difficult troubleshooting tasks on a motorcycle there is, and although I know that feeling of "I've almost got it!", you might want to trade services or some $$ to someone who REALLY knows what they are doing, and get it done. You will say, shoot! Thats what I was going to try next!, but really, a pro knows the method for this stuff. You got great heart for trying, for sure, but sometimes its time to just get it done.
For a newbee, you are trying to do a very complicated thing. No BS.
 
I got it running!

channelcat said:
I am thinking that what you are trying to do is probably one of the most difficult troubleshooting tasks on a motorcycle there is, and although I know that feeling of "I've almost got it!", you might want to trade services or some $$ to someone who REALLY knows what they are doing, and get it done. You will say, shoot! Thats what I was going to try next!, but really, a pro knows the method for this stuff. You got great heart for trying, for sure, but sometimes its time to just get it done.
For a newbee, you are trying to do a very complicated thing. No BS.
Click to expand...

ChannelCat, you're abundance of straightforwardness and kind words is much appreciated. I got the bike running today. :thumbup

I did research prior to purchasing the bike with my buddy and should have gone with my gut. The generic solenoid has the leads oriented flipped. To test this, I used some conductors with spade connector crimps and the bike started right up. :rofl



It's been really frustrating but I'm glad I've learned a lot from everyone's suggestions and efforts... even my uncle's. :x I now feel much more comfortable with working on the bike and next up with be the oil, spark plugs and carb (most likely in that order). :party

To think I'll need to spend $80 on harnesses and button assy to solve what I could have done with a pin remover. I'm going to rearrange the orientation by removing the conductor leads and place them according the generic solenoid.

Here are some resources that reminded me of my solution:
http://www.grizzlycentral.com/forum...hting/35442-starter-relay-solenoid-101-a.html
http://www.hondashadow.net/forum/72...versal-aftermarket-starter-solenoid-help.html
 
Ah, shit. If you'd have taken a picture of the solenoid, I could have told you a lot sooner.

We ran into this years ago on the CX forum when people were buying that solenoid type on e-bay and their bikes suddenly "stopped working."

I have that exact solenoid on my Eurosport.
The Honda connector just gets turned 180 degrees and slides right in if you cut off the locking tabs.
 
Last edited:
Sharky said:
Good job working it out.
Click to expand...

Thanks! :teeth

Tim-That CX Guy said:
Ah, shit. If you'd have taken a picture of the solenoid, I could have told you a lot sooner.

We ran into this years ago on the CX forum when people were buying that solenoid type on e-bay and their bikes suddenly "stopped working."

I have that exact solenoid on my Eurosport.
The Honda connector just gets turned 180 degrees and slides right in if you cut off the locking tabs.
Click to expand...

Hahah Yeah I figured that after the fact... but the plug on this particular aftermarket solenoid won't accommodate the connecter backwards, even after I cut the taps off. :thumbdown
But I'll unplug the pins and switch it that way. Just have to make sure that I swap it back if I come by an OEM or sell the bike. :thumbup
 
I would add that Nighthawks are awesome bikes. Worth fixing. Bulletproof engine, relaxed ergos, and very affordable.
 
Motorcycle Cannot Start

Yes, I have a 2011 cbr205r and is having the same problem.

The YouTube showed that the starting components are battery, starter switch, solenoid/relay and starter.

The dealer tested my new battery for free. They said the battery is good by looking at the battery tester.
They also checked for capacitance discharging from the battery. They measured the battery and waited for about 15-20 minutes. They took the reading again. If the voltage is lower, this means something somewhere is drawing current. This is without starting the engine. My battery does not have this problem.

This is my 1st time working on my bike/motorcycle on this issue. I am trying to learn and troubleshoot the right way and seeking help.

Thanks
 
Larry,
You might want to describe exactly what is or is not happening with your moto.
Based on what you said so far, no way to help.

Does the bike turn over?
Does it have spark?
Any recent damage?
 
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