Won't start!! Ignition problem? CA 125 / Rebel

[ajmackie]

Hi

I have just bought an '03 Hondal CA 125 / Rebel.
The kill switch seems to have shorted out the battery directly resulting in a flat battery very quickly.
I tried bump starting and jump starting and then resulted to disconnecting the battery and connecting jump pack battery.
The starter motor turns ove but engine just won't start.
Could the lectircal fault have melted some components requried for ignition?
Other than the CDI module, what else is involved in the ignition? Is the alternator rectifier used for powering the CDI module.

Plan now is to check if spark plugs spark, but just wondering what the iginition circuit consists of.

Thanks for any help.

[GearJammer]

Not sure how the kill switch depleted the original battery, unless the starter button had been pushed with the kill switch in the "Motor Off" position. I've seen kill switches that'll still allow the starter to turn but not catch, resulting in running down the battery. Have also seen other kill switches that won't allow "any" juice to flow at all...........(One of my personal pet peeves is kill switches, don't dig 'em, don't use 'em, tho' they obviously are a safety item)

Please ensure that your kill switch is in the "Run" position to make sure that it's not preventing fire-up as I'm not sure which type of k/s your CA125 has as described above.

Basic ignition circuit:

Ignition Switch activated by Starter Button
Battery
Starter Relay
Starter
CDI
Coil
Plugs

If I've got this right........Starter Button should allow juice to go from Battery thru Starter Relay to Starter to CDI to Coil to Plugs.

Once fire-up is achieved, the bike should run off the Alternator, which provides electrical current that is converted thru the Rectifier to replenish the Battery.

The CDI performs various functions, including allowing fire-up, allowing running idle, allowing ignition advance, etc., etc. The CDI can malfunction is different ways:
It might not allow fire-up
It might allow fire-up, but no running idle, in which case the bike would die shortly after fire-up
It might allow fire-up and running idle, but have no ignition advance, which means the bike would continue to run but not go over a certain required rpm.....the bike would run "flat", but it would run.

You're correct is checking for spark at the plugs as your first troubleshooting check. If there's no spark at the plugs, it's a matter of chasing it back to see where the electrical current is failing to proceed from. Examples: CDI might be preventing juice to coils, coils might be preventing juice to plugs, etc.

If you've got spark at the plugs, then I'd be inclined to at least suspect the CDI is not performing one of it's needed functions to keep the bike running properly.

(I'd also check all component connections to ensure that all connections are tight, all ground wires are in place & securely grounded. Would also check all fuses.)

[ajmackie]

Thanks for the reply.
I've located the CDI box underneat the fuel tank, so will check that out if there is no spark on the plugs.
I'm also going to check all of the cables and I was wondering how you take the seat off to be able to do this!
Does anyone know?

[ajmackie]

Also does anyone know where the fuses are located?
I've so far found 2 fuses strapped on the side of the battery holder and a fuse on the starter relay. Are there anymore which could have blown which would prevent ignition but allow everything else to work including starter motor? Thanks.

[GearJammer]

To remove seat......First remove the 2 bolts on the rear of the passenger pad, the front of the p-pad slips underneath a portion of the rider's seatpan. Once removed, it exposes the 2 bolts holding the rear of the rider's seat to the rear fender. If memory serves me right, there's one more seat bolt between rider's seat & gas tank.

For the brief time I owned the 250, the fuses that you're referring to are the only ones I remember finding. If there's another fuse box, hopefully someone will direct you to it's location. One of the fuses that you've already located is a spare. A bad fuse might not be the problem, but it's easy enough to check as part of your trouble-shooting list.

[ajmackie]

Right update time! ...
Bought a maintenance battery charger and battery is now fine!
Tested spark by removing plug and putting ht lead back on and holding by engine, no spark on either.

There's 2 connections to each coil. Each terminal had about 30-60mV on when testing to earth as I pressed the starter button, so I don't think there is enough voltage getting to the coil.
I tested the voltage across both terminals, nothing and no continuity when starting.

So sounds to me like there's no juice getting to the coils. I would have thought the CDI would put out a more substantial voltage to the coils, ie hundred volts.

Pulled CDI connector off, tested continuity to coil leads, so not broke (although interestingly the lead to each coil terminal has continuity going to the other coil terminal, so don't understand how engine can fire in an out of phase stroke to the other cylinder.
Didn't know what other inputs there would be to CDI. Guess there's a crank position sender but didn't know which input. There is also 12v on one of the connectors to the CDI, even when switched off.

Took seat off, checked all connectors were tight. Couldn't find any more fuses.

Disconnected wiring to right habd handlebar with kill switch and starter button. tested plug connector to find starter button wires and only connected starter button up. Still wouldn't fire. So guess kill switch in run position should work. Although maybe the wires are shorted between connector in junction box and CDI/starter relay.

So to conclude I guess it's the CDI, but not sure whether the fault is still there and may blow a new one?

Going to take it in to a motorbike shop to see what they can do!

[GearJammer]

You're to be commended on chasing down as much as you did. Right on!

If you had the Clymer's Manual for your Reb, it would more than likely give you the values when bench testing the coil for voltage rating. Coils work in 2 phases....the juice builds up, then the field collapses, releasing a MAJOR power surge to fire the plugs.

"There is also 12v on one of the connectors to the CDI, even when switched off.".....This part has me wondering. I could obviously be wrong, but it would seem that with the key turned off, there shouldn't be any voltage being sent to the CDI.

Could there possibly be a problem in the Ignition Switch itself ?

Considering that this is an '03, it sure would seem unlikely that either the CDI or coil would have gone south yet. Possible, yes, but just seems less likely.

It's your call as to whether or not you wanna chance trying this, O.K. ? When I first acquired the '85 250 Reb, wasn't getting any fire-up with the Starter Button, so I turned the key to the "On" position, then jumped the Starter Relay terminals with a screwdriver that had an INSULATED handle to prevent SHOCK.....bike fired right up! In my case, I believe the ultimate problem had been a compromised battery not having enough juice to make it thru the entire circuit, but by-passing a lot of it by directly jumping the Starter Relay did the trick until I got a new battery shortly afterwards....and I'm also hearing that your battery is good to go now, yes ? At least 12.5V when just reading the battery with bike turned off ?

[GearJammer]

Was thinking more about this & first off, wanted to apologize in that I forgot you had a 250 rather than the 125, but apparently the design is close enough so that it wasn't an issue.

The source of the prob still remains to be found, but wanted to offer some basic theory here...

On the Triumph chopper, I have no electronic ignition (no starter or starter relay) and I'm running without a battery, so it's a very basic system. There's an alternator/stator connected to the crankshaft. Using the kickstart lever, that turns the crank, which positions the pistons for proper compression needed for fire-up, but the turning of the crank also generates electric current thru the stator windings to excite the coil & allow ignition. Once running, the crank is turning under power, the alt/stator keeps providing the needed juice.

Coils themselves in a dormant state are relatively sedate. It's the coil windings inside that take in electric current & then amplify the current to a tremendous level, the field collapses & releases this JOLT thru the spark plugs.

For electronic ignition, such as on the Rebs, the Starter (which also has windings) provides the power to turn the crank to position the pistons for proper compression & fire-up. An alternator attached to the crank then continues to provide the needed juice while the crank is turning under power after ignition........Starter engages, crank turns, ignition is achieved, starter disengages, alternator picks up the continued necessary slack.

When the battery on my Reb was in a weakened condition, the Starter Button couldn't get enough juice thru the circuit to activate the Starter, which is why jumping the Starter Relay by-passed the weakened battery & allowed the Starter to engage as there's a certain amount of electrical energy stored in the Starter itself. Once running, it stayed running due to the current generated by the alternator, but I had to replace the bad battery in order to be able to use the Starter Button as designed.

Again, not saying this is the case with your's unless your battery is in a borderline state of charge. A fully charged battery is approx. 13.5V, but a baseline reading of 12.5V should be more than sufficient for the Starter Button to do it's thing. If not, then it's still a matter of chasing this down.

[ajmackie]

wow .. thanks for the very detailed reply! You've obviously put a lot of thought into it and i'm very grateful.
I don't think the battery power is a problem. The battery is holding 13.5v after charging so it seems to be fine. In fact there is so much pwer in the recharged battery that now when i press the kill switch (shorting the battery), the fuse blows on the starter relay fuse. Wished that had happened in the first place! Obviously wasn't enough power in battery then.

I think it's strange too that there is power to the CDI when off. I'm beginning to suspect some loose wiring that is causing chaos!

One thing I am wondering is that if the starter relay is in series, possibly on previous short circuit, current has melted part of it and is allowing power through to starter but not through to CDI when required?
As far as I can make out there are 2 main terminals on the starter relay ... 12v in, 12v switched out (to starter)? Then there's are 4 more terminals which I presume comprise of 12v out for when the ignition is on but not starter, starter button and ground and maybe a miscellaneous connection. Just wondering whether power is not correctly getting switched to CDI.

I have booked it in to a local garage. So hopefully they will be able to fix the fault. I really reckon it's just a wire that is loose/shorted as my mate who had the bike before me never had a problem with the kill switch shorting out the battery.

Thanks for the help, will keep you informed.

[ajmackie]

Oh yeah ... if the 'coils' located after the CDI are like a transformer and not a capacitor, then there should defo be voltage across the 2 termials. So defo CDI / loose wire! Thanks again!

[GearJammer]

You're definitely on the right track. Thanx for clarifying that the battery is definitely up to snuff. With the Starter Relay fuse blowing, it's more than likely a loose terminal connection, loose wire, bare wire or loose ground wire somewhere between Ignition Switch/Starter Button (actually could be in the control switch that houses Starter Button/Kill Switch, etc.) & Starter Relay. Would also have hope that the fuse itself is taking the hit & sparing any components from damage. Since the Starter Relay fuse is toasting, I'd be inclined to start there & work backwards in the circuit. Guess there's an outside chance of an electrical fault BEYOND the Starter Relay that's kickin' the juice back at it, but again, chances are it's somewhere in the circuit before/to the Stater Relay & dead-ending there. Good luck & please do keep us posted.....

[GearJammer]

Another thought to add to the list of confusion, LOL!

Might be a bad Starter Relay entirely..........or a bad Regulator/Rectifier......a compromised Reg/Rect might be sending TOO MUCH juice thru the gate.....Electrical probs are always an adventure, but you'll nail it down ;)