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#64441 - 05/30/10 10:14 PM Electrical Issues
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
I bought this bike over a year ago now and still haven't gotten over 10 hours riding time from it. Mostly from my lack of knowledge on bike engines. I have done some reading and research and hopefully with a few questions answered I can get this running asap.

The bike is a 1990 Yamaha XT225 and it's pretty much sat for 4-5 months now without being started (I have turned it over every month at least though a fair bit to keep things moving around while I work out how to start it).

I have the manual, but there are some other questions which I need to find out. I'll list the testing procedure I did below.

1. Fuse - ok
2. Battery - Car Battery, 12.8V (Fully charged - I can connect this to a charger at 13v or so to test when I go to start it if it makes any difference. I found the serow didn't like to start from the motorbike battery on 12v or just above, even with the new battery.)
3. Spark Plug - Person at the bike shop gave me a DR8ES plug, I'll get a DR8EA tomorrow, however I have a bit more than a spark plug problem with this no spark issue...
4. Ignition Spark Gap - Can test that when I get the new plug and other things in order first
5. Spark Plug Cap resistance was in specification
6. Ignition Coil resistance was 0.9ohm so close enough to the resistance values listed (It's about 15C outside) (0.56-0.84 @ 20C)
"Secondary coil resistance - Plug lead to Earth = 7.34kOhms (Specification - 5.68-8.52kOhm)
7. Main Switch - Red - Brown and Black - Black/White have continuity
8. Engine Stop Switch - One wire coming off with Red and Black and Blue... is this the Start switch wiring?
9. Neutral Switch - I'm sure the neutral relay is the same Sky Blue cable... if so there is ground continuity there. Green light comes on when the main switch Red and Brown wires come on
10. Sidestand switch... where is this!?!? - Possibly the thing in my picture, see attached.

11. Neutral Relay - now I had some problems with this... I tried to get the bike started and figured the relay had an input and connected a negative to two others. I connected these three cables and it sparked a tiny bit, nothing like a massive battery spark. Then my neutral green light went out.

Now temporarily I have been crossing the Red/Brown cables to start the bike since I lost the key. When I do this the green neutral light comes on and I can push the button and start the bike. Since I zapped them wires in (11.) the green neutral light doesn't come on now...It went off as I touched them, and then I disconnected the Red/Brown cables, the battery power, and even the light/instrument<panel>. Then re-connected it and still no green light. Wonder what I screwed up there now...

12. Charge coil resistances
<Step 1> Brown and Green leads = 441ohm (Spec -> 584-876ohm)
<Step 2> Yellow - Frame ground = Didn't get a reading... connections were good and tried over a minute here and there (Spec -> 20-30ohm)

I noticed no voltage rise when I had the bike working at idle, however I have been told I had to rev it for the volts to go up. When I first got the bike if I stalled it (happed alot because of the rubbish carby) it wouldn't start again (yes this sucked in the middle of nowhere, a few times... once I pushed it through about 2km of boggy sand, took me a couple hours). I replaced the battery and carb was tuned ok enough and it seemed ok after that to a certain degree. (I replaced the carb now, but gotta get it running to tune it!)

13. Pulser Coil Resistance - 848ohm (Spec -> 656-984ohm)

I guess my main questions in summary are:

11. What did I fry?
12. Is the charge coil the motorbikes "alternator"?

... and anything else anyone could kindly point out. I would be greatly appreciative of your time and endeavour to give back as much as I can.
I have worked on cars alot, and have good knowledge there... I'm just learning motorbikes now =(
_________________________
1990 XT225

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#64466 - 05/31/10 09:06 AM Re: Electrical Issues [Re: ]
sear Offline
Platinum Member
*****

Registered: 03/26/10
Posts: 854
Loc: Adirondack Park, New York
caveat:
I'm not a mechanic, and have little experience with in-depth motorcycle repair.

I gather one of the concerns here is getting the bike's charging system functioning.
Quote:
"I have been told I had to rev it for the volts to go up." nd

That's where I'd start.
Dial it up to ~4K RPM or so. If you get no indication of alternator output, then I'd suspect mega nailed it with the "regulator rectifier" (excellent pic mega!).

I don't have experience with such components in motorcycles. But in cars, simply reversing the polarity with jumper cables can blow out the diodes (or whatever), and the alternator becomes a doorstop.

And though I don't have the technical details, I've heard that not only can polarity reversal cause problems; but that a severely discharged battery (or a battery with problems, perhaps such as a shorted cell) can function as a short, and also cause problems with the delicate electronics in the "regulator rectifier". [I gather it can demand more than the alt. can provide (akin to a short), and mayhem ensues.]

Generally I'd exercise extreme care not to allow electrical surges in the system, apart from simply engaging the starter motor.

[confession:
In my teen years, when I couldn't get an engine started, I'd get the vehicle up on top of a long steep hill, get some speed into it, and then get it in a fairly high gear (3rd or 4th*); ease off the clutch, and get ready for the engine to start running on its own.
Obviously that has to be able to happen, so make sure it's in shape to do so.

* First gear gives the engine maximum mechanical torque advantage over the road. Conversely top gear (5th) gives the road maximum mechanical torque advantage over the engine.
To spin an engine, particularly a newly rebuilt one, I use the mechanical advantage of a high gear.

Good luck nd!
_________________________
2009 XT250 w/ 16T, 12 VDC socket, tank pannier, winged access screws
"Safety is no accident."

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#64469 - 05/31/10 10:27 AM Re: Electrical Issues [Re: sear]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
Thanks guys, when I can get it started again I'll test those components straight away. I am thinking of doing a complete rewiring job myself. No idea what yamaha would charge for a new harness, and I'm setting up to mature age study at uni next year so giving myself this time off to get my car/bike/other things all fixed up and finished before I prepare to be broke for four years =P

RE: the reverse polarity issue, didn't think of it like this. From what I've read so far - stator and regulator/rectifier's go, however what I might do is re-test the electrical components, then work out what a new loom is worth (as you can see this one is old and ugly) - however I'd rather make my own... then buy generic components such as regulator etc. I have put a new quality china coil in there and it seems fine, and cost me $20 or something.
_________________________
1990 XT225

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#64472 - 05/31/10 02:29 PM Re: Electrical Issues [Re: nathan_d]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
Capacitor sticking out the bottom of the reg/rec has a broken leg! I'll resolder it and seal it up, and that should solve my charging problems... now just to work out what I have fried so I can get that neutral light back on.
_________________________
1990 XT225

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#64517 - 06/01/10 03:09 PM Re: Electrical Issues [Re: ]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
In regards to reverse polarity (i'd assume thats what caused the spark and no power)

I checked the fuse, should i now check stator and then replace the reg rec anyway? Is there any way of testing the reg rec with the engine off?
_________________________
1990 XT225

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#64566 - 06/03/10 12:06 AM Re: Electrical Issues [Re: ]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
Thanks that's an awesome site. I just have to get the bike started first. I am a bit lost on which components to replace so thinking about replacing them all and just having spares.

What would fry on a reverse polarity'd bike? Reg/rec I am told since this is the thing that converts the AC current from the bike output to the DC current for the battery. So I am right to assume the current won't flow backwards through the reg rec and just fry it instead?
_________________________
1990 XT225

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#64589 - 06/04/10 12:28 AM Re: Electrical Issues [Re: nathan_d]
porklunch Offline
Member L1
*****

Registered: 04/16/10
Posts: 149
Loc: semen cuntry
that thing hanging is ur rear brake switch

test ur switches with ohm meter. bypass if bad. also the sidestand switch = kickstand switch. if its there u will know its there. if you could put ur kickstand down with bike in gear its probably bypassed already.

im not sure what the voltage from the generator going into your regulator/rectifier is. but you could get a transformer that outputs a voltage close to whatever that is and then measure the output which should be ~12v dc. Might end up a little lower because you would only be putting in 1 phase so it wouldnt be as clean of an output.


by the ohm measurement of your charge coil id say its bad. Low resistance means the insulation is worn through and making the path through the coil shorter. You could probably get it redone somewhere or buy a whole new stator.

also test that capacitor that broke off. reverse polarity on electrolytic caps ruins them. im not sure what kind of cap is on the regulator/rectifier tho.

you can check all of your relays using ur meter. apply 12 volts across the coil on the relay with correct polarity. and the contacts should close if normally open. or open if normally closed. use ohm meter to see change in contacts.
_________________________
[censored] cock lickers

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#65853 - 06/29/10 01:44 PM Re: Electrical Issues [Re: porklunch]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
Sidestand switch is bypassed.
I have to replace the capacitor tomorrow.

I had some issues with the charging cycle when it was running. Batteries would go flat and not hold charge and in the beginning when it would die up a hill I couldn't get it started again unless I hooked it up to 12.5++v, at 12.3v or lower it would turn over fine but wouldn't fire.

The bike had 20,000km's on it when I bought it and was completely standard and original owned by an older bloke who looked like he didn't thrash it. It rides really good and I paid $1200 for it, just so sad to see it has spent now a year and a half in my possession and I been out on it less than 10 times =(

My poor lonely trailer awaits.

I'll get a quote on a stator tomorrow and just see if I can resolder another capacitor in the regrec. Then after the stator, or maybe at the same time depending on how long it takes, I'll get a new reg/rec. Hopefully that should be most of the problems.
Thanks alot for your help, I really appreciate it. I'll update soon.
_________________________
1990 XT225

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#65921 - 06/30/10 05:04 PM Re: Electrical Issues [Re: nathan_d]
halimaw Offline
Junior Member

Registered: 03/12/08
Posts: 3
Loc: philippines

xt225 got a 3 phase alternator and a 3 phase rec/reg. our rec/reg has a 5 connection 4 pin socket(3 connection came from engine alternator and a connection going to battery) and a body ground. at idle speed your voltage rating should be slightly below 14v and 14v at full load. from your case It's either you have a faulty stator/alternator or a busted/faulty rec/reg. hope this will help.
_________________________
bwahahahaha

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#65922 - 06/30/10 05:08 PM Re: Electrical Issues [Re: halimaw]
halimaw Offline
Junior Member

Registered: 03/12/08
Posts: 3
Loc: philippines
oh i forgot to tell you the above image is schematic diagram of our rec/reg. from rectifier to regulator side. except for the (to switched batt. connection) that should go "to batt." connection.
_________________________
bwahahahaha

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#75330 - 01/29/11 04:07 PM Re: Electrical Issues [Re: halimaw]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
Well six months later again Im having another crack at it.... I figure I'll just keep spending money on replacing the old parts.


12. Charge coil resistances
<Step 1> Brown and Green leads = 441ohm (Spec -> 584-876ohm)
<Step 2> Yellow - Frame ground = Didn't get a reading... connections were good and tried over a minute here and there (Spec -> 20-30ohm)

I figure the charge coil is buggered because when I removed it, it was a bit black. Going to replace it this week. I think I got it sorted now, the manual has most of the details to fix this type of problem and get it running at least.
_________________________
1990 XT225

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#75338 - 01/29/11 09:01 PM Re: Electrical Issues [Re: nathan_d]
Drew-NY Offline
Junior Member

Registered: 08/16/10
Posts: 60
Loc: Liverpool, NY USA
Hello Nathan,
I think I can help with your problem, let's give it a go.

If I understand correctly you have two problems. It no longer runs because it doesn't have spark and back when it was running it wouldn't keep the battery charged.

The starting system and ignition system are independent. They share a few parts but electrically they are separate.

I assume there are no problems with the starting system. The starter motor cranks the engine OK?

There are two key wires to check concerning the ignition system and a no spark condition. The black/white and blue/yellow wires at the CDI module.

1) The black wire with a white tracer goes to the ignition key switch. This wire must be open circuit to allow spark. When the key switch is off the wire gets grounded and kills the spark. If you don't have the key and you are trying to start the motorbike by jumping the red wire to the brown wire then you must disconnect the black/white wire either at the key switch or at the CDI pigtail.

2) At the CDI module there is a blue wire with a yellow tracer. This wire must be grounded to allow the CDI to provide spark. If the blue/yellow wire is not grounded then check the following parts: sidestand switch, neutral relay, engine stop switch. The sidestand switch is located above the bolt that mounts the sidestand to the frame. It must be closed when the sidestand is up. This is the part responsible for killing the engine if the rider puts the transmission in gear but the sidestand is still down(a safety feature). If the blue/yellow wire has any voltage on it then there will not be any spark.

Under the left engine side cover is the CDI magneto / alternator. This assembly does three things: 1) provides the energy to the ignition system to make the spark at the spark plug. 2) provide a timing signal so the spark occurs at the right time. 3) provides power for the charging system so the battery won't go flat.

The brown, green and yellow wires are the ignition charging coils for the CDI module. These two coils provide the power to create the spark at the plug. The white and red wires are the pulser coil to signal the CDI module when to send the spark to the spark plug. The three white wires are the alternator output to the rectifier/regulator unit to charge the battery.

In your post about the yellow wire measurement you didn't get a reading? Did you mean it was open circuit to ground or shorted to ground? If you have the left engine cover off look for a black wire that comes out of the copper windings to a ground screw somewhere. Measure resistance from the yellow wire to the black wire that is supposed to be grounded. I would be surprised if any of those coils were burned up. A magnet spinning around outside them can hardly create enough energy to burn the varnish insulation.

The capacitor on the rectifier/regulator is for electrical noise filtering. I would not expect that to have any adverse effect on charging the battery.

Andrew
_________________________
2008 XT250, 2005 FZ1, 1981 GS750, 1978 KZ400, 1973 RD350

I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts.
-Abraham Lincoln

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#82693 - 06/02/11 07:40 AM Re: Electrical Issues [Re: Drew-NY]
nathan_d Offline
Junior Member

Registered: 05/30/10
Posts: 16
Loc: Perth, WA, Australia
_________________________
1990 XT225

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