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Changing Alternators

9.9K views 55 replies 5 participants last post by  flitecontrol  
#1 ·
So as the title says I am changing alternators. I have an 83 cm250c. I rewired the entire bike head to toe. not the first bike i have worked on but I was also a diagnostics car mechanic for over 10 years so i know what I am doing lol. anyways the alternator crapped out on my bike. i want to buy a new one but for $200 its just not in the cards right now. i did however get a free alternator for a (known working) 2000 honda rebel. This one has one less wire coming from it then the original. is there anyway to make this work or am I S.O.L.?
on a side note i was able to rebuild my starter clutch with springs i purchased from harbor frieght in a kit for like $5.00 just an F.Y.I.

PS. bike was running and just not charging. i plugged the new one in just to see but i didnt even get spark. i am confuse because the alternator shouldnt have anything to do with spark, or are bikes that much different then cars? let me know. thank you
 
#2 ·
are you changing the entire stator?
Have you tried replacing voltage regulator?

there are 3 functions to stator and flywheel combination..
3 phase AC charging current sent to rectifier/regulator which are the three yellow circuits..

A Red/Black AC circuit supplying 100-400vac to CDI as well as a ground

than there is separate pulse generator coil with Blue/Yellow and Green/White wires located externally from flywheel whose magnet triggers pulse causing CDI to fire the spark plug coils..

the Rebel ignition most resembles magneto type system used on most reciprocating aircraft engines.

btw it has been found the 2nd generation 96-2016 Rebel stator is larger than 85-87 Rebel so your 2000 replacement may not fit inside the CM250 flywheel.
 
#3 ·
voltage reg. is brand new. as is the pulse generator coil. as for the magnets i was removing the flywheel and as i went to unscrew them they were shattered to bits. previous owner couldnt get the flywheel off so he hit it with a hammer... i was able to get new, thinner magnets in there with the same force pull as the previous original magnets.
the 3 yellow wires shouldnt matter which pin they are in, correct (differentiating between the years and models)? as for the red/black wire should serve the purpose that the old alternators white and blue wires were used for. in the wire diagram it shows that the white wire and blue wire are connected in the alternator only seperated with a resister. with that being said, should i be able to just connect the red/ black wire to a white and blue wire granted i put a resister in there before the cdi?
 
#5 ·
I think most of us are just overwhelmed by how many things could be wrong. I'm just trying to think about where to start. I've never heard of anybody replacing the magnets in the flywheel, have you done that before? I think it would be better just to replace the whole flywheel.
 
#6 ·
I don't have the money to spend on a new flywheel nor will i anytime in the relatively near future. I have not done it before though i am pretty sure it will work, but what's a better time to see if it could work then now. Like i said though they are just smaller (thinner) magnets with the same force pull as the others were, but my issue is with the electrical portion of it for now, if it can't be done then the bike(my only means of transportation at the moment) is doomed to stay put until i get out of the financial dilemma i am in right now
 
#7 ·
Most of us have been there between a rock and a hard place before when it comes to money and transportation and taking care of our needs. A lot of understanding about that one.
I'll let the skilled people give you answers. I don't pretend to be as skilled as many of those that reply.
 
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#8 ·
Most of us have been there between a rock and a hard place before when it comes to money and transportation and taking care of our needs. A lot of understanding about that one.
I'll let the skilled people give you answers. I don't pretend to be as skilled as many of those that reply.
Okie dokie. Thanks for the response though
 
#9 ·
I've pondered about the placement of yellow charge coil wires in the past whether phasing is important or not..
honestly I'm not familiar with the 8 wire CDI operation of CM250T i see in wiring diagram..
I see Blue, Green, White, Pink, and Light Blue circuits from stator.
No indication is made which does what in the diagram I have.. nor do I see resistor between Blue and White..
Can you post an image or scan of your wire diagram?
This is a cutout from the CM250T charge/ignition wiring I have to go by. As you can see the alternator internal windings wiring leaves a lot to be desired..

Image


this is what I have to work off of for Rebel alternator

Image
 
#13 ·
yea I just picked up that CM250C wiring diagram elsewhere while looking up the CM250 CDI.. I found most were 7 wire rather than in the 8 wire wiring diagram I had..

your Blue and White wires are not interconnected with a resistor, that is a winding and appears that CDI is supplied with a 2 phase charge as flywheel magnets pass over the two separate windings..

No dumb questions here only uninformed do it yourselfers searching for answers. i'm not familiar with this setup doubt you can make Rebel stator work even if your flywheel magnet replacement is working..

Image
 
#15 ·
Does this CM250C stator look like yours?
I find at least one used 31120KB4005 CM250C stator on eBay

It differs from 1st generation Rebel stator in that it has 2 larger windings opposite to one another to power CDI..

Image


1st gen 85-87 Rebel only has One large winding powering CDI
The 2nd gen 96-2016 stator has two windings to power CDI placed beside each other.. The 2nd gen stator is slightly larger in diameter and makes physical contact with 1st gen flywheel which isn't good..

Image


you might get spark by connecting just the Blue or White lead to Red/Black stator wiring.. I wouldn't count on it though.. would also be concerned about damaging a good CDI
 
#16 ·
That's exactly what i was looking for. Yes i do have the second gen stator but it does not make contact with the flywheel because of the magnet mod i did. As for the wiring. So either white OR blue correct? Not both connected to the red black? The regulator im only half concerned about. It's still under warranty and i know they'll accept it if i do fry it. Thanks again. Right now im cleaning my garage, something I've held off for a while. But when i have a minute or two ill tinker with it and let you know
 
#18 ·
No I don't know of stator rebuilder though I came across this one in the past
Ricky Stator - Stator Rewinds or
I've seen others listed on internet searches

several 1st generation owners have looked for replacement stators when theirs gave up the ghost, I know of no one who had theirs rebuilt..

Not uncommon to need replacement of obsolete stator..
the Honda Twins forum has DIY threads
as well as threads about dual windings powering CDI
Check Recommended Reading threads listed at bottom of pages

I think I would connect Red/Black to a single circuit, Blue first than try White.
 
#19 ·
Thanks a bunch. I didn't have a chance to get to it today but i did look at wiring diagram comparisons. Technically if i change the cdi as well then there shouldn't be a single problem with wiring at that point. It would eliminate the blue and white wires
 
#20 ·
yes a 2nd gen CDI would solve the wiring problem..

I've been using this 2nd gen aftermarket version on 87 Rebel since 2017

you can read writeup of adaptation to 1st gen

the ground and side stand safety interlock can be connected together
Image
 
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#21 ·
Ok so i was able to acquire a known working cdi for relatively cheap. I don't have the time at the moment to wire it up but tomorrow I will. As soon as I have it hooked up I will let you know how it goes. So to recap I have a 2000 rebel stator in my 83 cm250 and the flywheel has thinner magnets installed so the stator can fit. Next step is to wire up a 2nd gen cdi (from a 2003 rebel) to the harness and if all goes well, i won't die.... (joking). Wish me luck!
 
#41 ·
So I kind of have an issue getting the bike back together.
Good luck.
I too learned a bit more about winding a stator..
if it ever comes to it, I'll closely observe which direction the windings are wound
Hey bud, I have a question about the cdi. So since I have the original stator once again , is it possible to hook up that second gen cdi to it? If so my problem is with the wiring. First off the connector to the cdi is lost. I don't know where I set it down. But on the picture you sent it shows that the 2 pin connector has a red and black wire coming from the exciter. On my stator I do not have the red and black. My stator has 3 yellow then the white and the blue wires. I know you said connect the ground to the kick stand wire but which one should be the exciter?
 
#23 ·
I have a different question about your cm250 if you don't mind? That has a center stand does it not? Do you think it'll fit a rebel?
I've been watching this thread with much curiosity. I hope all goes well with your repairs.
 
#24 ·
Yes it does have a center stand, but to be perfectly honest I do not know if it would be a direct fit. Im sure with a little fabrication you could get it to fit if it doesnt at first but that goes without saying. and I dont know if its just my bike or if all the cm250s are like mine but to get it on that stand is a huge pain. twice ive caught my foot between the center and side stand when getting it on the center.
 
#25 ·
Thank you. I ordered you CM250 Center stand. I'll have to make sure I design it such that my foot doesn't get caught 😋!
 
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#27 ·
Raising the side stand before putting the bike on the center stand will get it out of the way, but shouldn't be needed when using proper technique. How to get a motorcycle on and off the centerstand - YouTube
[/QUOTE]
i bought the bike used and cant put the cented stand down when the other one is up. I couldnt figure out why. i know how to do it on other bikes, this one is a special case though heres a before and after of the bike
Image
 
#29 ·
Looking forward to see the pictures of the changes as they happened.
 
#32 ·
well i am sorry to disapoint everyone that was a part of this, but today I went to donate plasma and while i was out someone broke into the garage and stole the bike, my tools, and anything else of value. so right now im back to square -1. only thing my cameras saw was a truck with no license plate and some people wearing hoodies
 
#34 · (Edited)
It wasn't you that gave the disappointment.
So sorry! This world is getting worse everyday.
Police have any ideas or hopes for recovery?
Someone was obviously watching close by. Check your camera for a few days prior. You may have caught the criminals on camera casing your home previous to this.
I know my brother did with his cameras. He posted their likeness on the outside of his house. The man was looking straight at the camera.
 
#35 ·
I have blink cameras so they only get about a minute at a time. I have an idea of who it could be but it's not like I live in the safest neighborhood to begin with... so who knows, maybe they can't fix the bike and they leave it somewhere. Doubt it. But wishful thinking. Thanks again everyone
 
#36 ·
Well good news and bad news. Bad news is bike was recovered. Not by police but found on the side of the road. Not sure what they did aside from ruin my day but almost everything seems intact besides the seat missing. Luckily I got a spare. Now for the good news. I was able to get some money together from a side job to buy the parts I actually need for the dang thing. Keep a look out for a page called " there is no I in parallelogram" just kidding itll be called "someguys cm250"
 
#45 ·
I was thinking about the recent debacle when the bike was stolen. I was wondering if you had the steering locked if they'd have still taken it. Anything to make it harder. We all know that thieves HATE anything that makes work. Thieves are lazy, that's why they try to make money off of someone else's work.