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Discussion Starter · #1 · (Edited)
so my 1985 Rebel 250 (with 1986 engine in it) has been having trouble starting with the start switch..

starts right up when I bridge terminals.. headlights dim but no click at the solenoid. have swapped solenoids and switch.. going to clean contact points inside switch with electrical cleaner.

just wondering if anyone has a picture of where the designated connection point for the negative/ground cable goes from battery to frame?

this is on a Gen 1, 250cc


I have the rest set up good to my knowledge but I can see headlight fluctuating when I rev bike, but when I press on the cable it stops doing it.

had it elsewhere in wrong spot.
(I had it pinched between metal battery cover and metal battery box) ...

amazed it even ran headlights etc while driving like that.. after doing some research, at this point, Im thinking might just be bad ground causing it to not start with switch.

when I start it up by bridging the solenoid terminals, it starts right up and runs great.. just took it for a ride today.

dont ask me why I thought that was right but I think bike came like that. o_O

hoping someone can help me find the correct place to connect it, and then I will work on sanding to bare metal and making it a solid connection.
 

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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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When you say you bridge the terminals, you mean you bridge the terminals at the solenoid correct? If so, and the engine starts, it means you're grounding is good. Jumping the solenoid is connecting positive across to the starter motor, that's all. Did you try taking a positive wire the solenoid actuator circuit to see what happens?
It sounds like your starter switch on your right hand control maybe the problem. They get very dirty and corroded at times. I've not had this problem yet, mine are stored indoors. But the PO of 1 of mine, had stored it outdoors for about 6 years. I'm sure I'll have to clean it soon.
When cleaning it make sure you have it in a room that is wide open and clean. There's a small spring in there which can let loose with great force and get lost and you won't find it otherwise when you take it apart.
Sometimes you can just take some contact cleaner and spray it in the side of it and work it back and forth by pushing the button pushing the button pushing the button.(Sorry, I just noticed that you said that you're planning on doing this already).
 

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1987 CMX250C AC
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My guess is the starter solenoid has a ground problem..
refer to 1st generation wire diagram

Starter button provides two functions, when depressed connecting Black power circuit to Yellow/Red starter relay while disconnecting Headlight circuit thus all current is available to starter. This is why headlight shuts off when button pushed..
Product Rectangle Font Parallel Pattern

So if you follow the Yellow/Red circuit from starter switch it leads you to Relay..
Relay has a couple of grounds.. Follow Dark Green/Red grounding circuit to Left handlebar switch assembly where it connects to Clutch Lever Switch which in turn connects to Green ground circuit..
Second grounding point for starter relay is where Dark Green/Red also splits off connecting to Clutch Diode.. Light Green/Red is connected to other side of diode leading to Neutral Switch which provides ground through engine case..
 

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The more I think about it @Emil is probability correct, source voltage from switch is interrupted rather than a grounding problem.
 

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Battery neg cable ground attaches to engine case as seen in following post

A cable can be eaten away or broken under the insulation and not be noticeable, but I would look for dirty/loose connections if pressing against it improves fluctuating headlight performance..
Voltage may fluctuate with increasing rpm, 85-87 specs are 14-15 volts at 5000 rpm
Rectangle Font Parallel Art Pattern
 

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Discussion Starter · #6 ·
The more I think about it @Emil is probability correct, source voltage from switch is interrupted rather than a grounding problem.
so you think it could be the wire from switch to solenoid? whats the best way to re-wrap my harness if I cut it open? leaning towards the $10 amazon starter solenoid. I have a beautiful harness from the 2001 but was trying to avoid that.. however it would be less of a cluster-F if 20 years newer.. I believe I would have to switch out battery box and fuse holder.. any other differences? I ordered my H4 connector, but im waiting for Jacks to be back in stock with the newer style housing. the headlight is way too dim stock.
 

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Make sure it's in neutral. Then try taking + from the battery to the side of the solenoid where the yellow/red is attached.
Does it crank? If so, it's either the start button or the wiring between.
Leaning more towards the start button as these are well known to have corrosion issues.
 
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Discussion Starter · #9 ·
Make sure it's in neutral. Then try taking + from the battery to the side of the solenoid where the yellow/red is attached.
Does it crank? If so, it's either the start button or the wiring between.
Leaning more towards the start button as these are well known to have corrosion issues.
I did try your suggestion today.. running small jumper wire from positive battery terminal, to the solenoid terminal with red and yellow wire coming from it.. and it starts right up..
I also cleaned 2 different switches I have internally with contact cleaner and tested both while I had the junction box open, to no avail..

However; I did find this small scuff on the wire just behind the bullet connector for solenoid (harness side) and wondering if this would be enough to interrupt the current.
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just wondering if anyone has a picture of where the designated connection point for the negative/ground cable goes from battery to frame?

The ground goes from the battery terminal directly to the engine casing.
 

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Since it started right up, the solenoid is good. Keep following the wires with a voltmeter & you'll find it. 👍
 

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Discussion Starter · #12 ·
Since it started right up, the solenoid is good. Keep following the wires with a voltmeter & you'll find it. 👍
I know this should be pretty basic test, but I would just attach the black voltmeter lead to any ground?
and then red/pos volmeter probe at different points along the red and yellow wire?
which way should I work? from solenoid to switch?

how to I tap the positive wire midstream with voltmeter probe? and I will need to test the red and yellow wire with key on and the start button depressed, correct?
 

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If you can clip on to the negative terminal of the battery it would be best. But clipping on to a good solid point in the frame would also work, or even the engine block.
As far as the yellow/red wire, the point where you have that bare spot, you can test there with the button pushed to see if you have power at that location. If not, the next point would probably be in the Rat's Nest of a junction in the front of the bike behind the headlight. If you still don't have power there & the headlight works, it's the switch.
 

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In the junction box behind headlight you should find a 6 pin/prong connector containing circuits you want to investigate..
Test the by inserting multimeter probe into backside of connector.
Black will be energized when ignition turned on..
Brown/Red as well as [Brown/White (Brown/Blue)] are both powered by Black circuit when ignition switch turned on, so they should be powered up too.

Yellow/Red will only be energized when start button pressed..
Yellow/Red runs from junction box connector to starter relay.
Rectangle Slope Schematic Font Line
 

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Discussion Starter · #15 ·
In the junction box behind headlight you should find a 6 pin/prong connector containing circuits you want to investigate..
Test the by inserting multimeter probe into backside of connector.
Black will be energized when ignition turned on..
Brown/Red as well as [Brown/White (Brown/Blue)] are both powered by Black circuit when ignition switch turned on, so they should be powered up too.

Yellow/Red will only be energized when start button pressed..
Yellow/Red runs from junction box connector to starter relay.
View attachment 114987
update: I used a 12v circuit tester on yellow/red wire both on inside of starter switch and where it meets the starter solenoid, while hitting switch,
and they both lit right up.

I have also tried 3 different starter solenoids. I have 3 starter switches on hand..
have tried 2 so far, and cleaned the contact points inside the switch as well as well as the solenoid itself, and the ones inside the fuse box.

I discovered that my harness ground wasnt even connected, so that fixed the headlight fluctuating... I fixed the frayed wires. going to get the H4 housing from Jacks and use that to make brighter.

regardless, it still hasnt solved the problem.
I got some 7.5 amp fuses and now have those on hand.. but I blew the 15 amp one, and have been putting the 7.5 ones in its place temporarily.
they naturally have been burning up alot, but would that affect the starting at all?

** I basically have power at both ends of the yellow/red wire, and based on the test we discussed above, it sounds like solenoid is good. and my ground connections would have to be good or it wouldnt start when bridging terminals, correct?

So where does that leave me?
I'm guessing switch itself, the switch ground?
keep in mind I have already tried 2 switches so far.
 

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I have 3 starter switches on hand....

keep in mind I have already tried 2 switches so far.
Just so we're talking about the same thing, you replaced two of these? I'm not trying to be smart, I'm just wanting to make sure that we're on the same page.
The other thing that I'm curious about is when you say
**basically have power at both ends of the yellow/red wire, and based on the test we discussed above, it sounds like solenoid is good. and my ground connections would have to be good or it wouldnt start when bridging terminals, correct?
So you have 12VDC when pressing the starter button at the solenoid on the yellow/red wire? I'm wondering if it's what the guys at work used to call 'ghost voltage'. Meaning that a highly resistive circuit will read the correct voltage until it's under load. It still sounds like a poor connection either in the wire or on the button switch.
 

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Discussion Starter · #17 ·
Just so we're talking about the same thing, you replaced two of these? I'm not trying to be smart, I'm just wanting to make sure that we're on the same page.
yep, unfortunately.
had to go through the junction box and everything. ended up having to take apart every connection inside and then pack it all back in, twice..

so kinda hoping someone can give me an idea of where to go next since there is power at solenoid and switch as far as red and yellow wire goes.

I also checked the black wire connection and it had power with ignition key turned.

solenoid does not click when I hit start button, but the lights do dim, and the bike starts right up if I bridge the terminals or if I jump from + battery terminal to the red/yellow terminal of solenoid.

(from what I have collected from this thread, being able to start it these methods means my ground connections and my solenoid are both good)


Im thinking that leaves switch and thats about it?

Im sure it could be solenoid ground.. if so, cant I just tap into the ground wire and manually ground it or tap it into another ground wire?

prefer not to cut my entire harness open if all my grounds are good.

I have one more switch left to try, but I checked and cleaned all my internal connections on both switches with contact cleaner pretty thoroughly, I thought so anyway.
 

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Well one thing you could do is if you have a whole brake light from a Rebel, you can attach that to the yellow/red lead at the solenoid location to the green/yellow, & see if the brake light comes on brightly. (Of course grounding the dark green lead from the light 1st). This should be an approximate equivalent to the solenoid load. If it won't come on, or does but very dimly, you still have a poor connection somewhere, most likely at the button.
 

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Discussion Starter · #19 ·
Just so we're talking about the same thing, you replaced two of these? I'm not trying to be smart, I'm just wanting to make sure that we're on the same page.
The other thing that I'm curious about is when you say

So you have 12VDC when pressing the starter button at the solenoid on the yellow/red wire? I'm wondering if it's what the guys at work used to call 'ghost voltage'. Meaning that a highly resistive circuit will read the correct voltage until it's under load. It still sounds like a poor connection either in the wire or on the button switch.
I just used a test light, but I do have a voltmeter. so tomorrow Im going to test DC voltage at that point on solenoid..
here are a couple pics on my solenoid connections and the inside of my switch after a bit more cleaning...
I put some down in behind the Start button, like alot, including the lil piston it moves in and out with.
going to let it dry.

Let me know if anything stands out in the pictures.


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Discussion Starter · #20 ·
Wheel Tire Car Land vehicle Vehicle


got a windshield on it now 8)

this not starting with the switch thing is the only issue.
I have since swapped rear turn signals for newer-gen-style (bigger)..

I have an entire 2001 Rebel 250 wiring harness thats in great shape and solenoid/battery box to go with it but I want to rule out everything before doing that.

Does anyone know if the two harnesses have any differences besides the solenoid / battery?
 
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