72 honda CL100 stator replacement?

scrambler · 07-19-2012, 01:34 AM

I have a 1972 Honda CL100 Scrambler that has, you guessed it, electrical problems. I've done a lot of work on this bike, replacing most of the electrical, rebuilding the engine, blood, sweat, tears. IT runs quite nicely, usually starts within three kicks, drives like a champ BUT the battery doesn't get fully charged. What I'm reading is that these bikes weren't designed to have the headlight on all the time, that it can't keep up with recharging the battery. If I go on short rides then plug in the battery tender, the bike will be ready to go the next day, however, if I take it on something longer I run the risk of draining the battery and getting myself stranded.
The stater is the one thing I've done nothing to. Some out there talk about getting a replacement but that costs up to $175 or more. Others have hinted at a process that re-magnetizes my existing stator. Does anyone out there in internet land have any experience solving the problem of the little stator that couldn't?

Doug Northey · 07-19-2012, 08:47 AM

hi;
two things control the output of the stator on these 100's.Engine RPM,and magnet strength.The first two tests on the stator should be(in this order)check resistance between the stator wires.On many of the older bikes that would be yellow-white-pink coming out of the stator,and on newer ones yellow-yellow-yellow.Anyway resistance between them should be around 3-6 ohms,and check them from each wire to ground.To check for ground short use a good ohm meter(or good lighted contnuity tester).No continuity to ground should be present.If continuity to ground is found the stator is bad(a very slight grounding will cause the battery to discharge slowly while riding).A good rule of thumb has been if the battery goes down while the bike is parked (not being used) look at the rectifyer.If the battery goes down while riding,look for a no charge or stator short.
The magnet in the rotor is another story.If the magnets get weak(and over many years they can)the system just can't charge enough to keep up.No reliable tests have come from honda to test rotor magnet strength.We have had to rely on comparrison to a known good unit or common screw driver test.The screwdriver test is you take a screwdriver and hold the end near the magnets and see how fast and hard the screwdriver is pulled to the rotor.Compare this to a good one and remember the feel.Sounds cheesy but works.Remember that these little bikes didn't break even(charge) till almost 5,000RPM.So when one rides these bikes on the street it is a constant battle to remember to use the brake light and the signal lights with care(they draw more than the system puts out).Back in the 70's I always had people who complained about low batteries on these bikes.So I started riding o demo back and forth to work(60miles a day) for a month to see if I could duplicate the problem.I could,by setting at a stop with the brake applied,or sitting at a light with the brake appied and the signals on the battery would be low in no time.I tried to educate the owners on battery life and how to manipulate the system to keep the battery up.Some did good and others didn't.I used the demo for two weeks and had no battery problems.
Anyway I hope all this has (or will) help you with your bike.

scrambler · 07-23-2012, 09:17 PM

Thanks Doug for the pointers. I will have to figure out how to test the output on the stators per your directions and see how it does. I should've mentioned that this bike is actually a 125 thanks to a bore job/bigger piston head.
I also discovered today that my tail light bulb was actually a 12 volt so I bought the appropriate 6 volt replacement. I'm wondering if trying to find LED light bulbs for the tail and turn signals might help. I just want to be able to drive across town without getting myself stranded.

skyhawk · 08-28-2012, 06:36 PM

A LED will work for your brake and tail light, it will not work for your blinkers without modification. SuperBrightLEDs.com will most likely have something that will work for you at a reasonable price. I put blue leds in my old yamaha instruments and it looks pretty cool at night.
There is a way to use LEDs for the blinkers but your existing relay will not work because it works off of resistance, and leds basically dont have any. If you like I can seend a link from a diffferent board... they are doing it on 12v newer bikes.

letsgocouchman · 05-01-2013, 02:26 PM

i had the same problem on my 71 CL100. never did find the problem though. ended up selling it before i had the chance.

07-19-2012, 01:34 AM	#1
scrambler Motorcyclist Join Date: Jun 2011 Posts: 9	72 honda CL100 stator replacement? I have a 1972 Honda CL100 Scrambler that has, you guessed it, electrical problems. I've done a lot of work on this bike, replacing most of the electrical, rebuilding the engine, blood, sweat, tears. IT runs quite nicely, usually starts within three kicks, drives like a champ BUT the battery doesn't get fully charged. What I'm reading is that these bikes weren't designed to have the headlight on all the time, that it can't keep up with recharging the battery. If I go on short rides then plug in the battery tender, the bike will be ready to go the next day, however, if I take it on something longer I run the risk of draining the battery and getting myself stranded. The stater is the one thing I've done nothing to. Some out there talk about getting a replacement but that costs up to $175 or more. Others have hinted at a process that re-magnetizes my existing stator. Does anyone out there in internet land have any experience solving the problem of the little stator that couldn't?

07-19-2012, 08:47 AM	#2
Doug Northey Verified Join Date: Nov 2010 Posts: 62	cl100 stator hi; two things control the output of the stator on these 100's.Engine RPM,and magnet strength.The first two tests on the stator should be(in this order)check resistance between the stator wires.On many of the older bikes that would be yellow-white-pink coming out of the stator,and on newer ones yellow-yellow-yellow.Anyway resistance between them should be around 3-6 ohms,and check them from each wire to ground.To check for ground short use a good ohm meter(or good lighted contnuity tester).No continuity to ground should be present.If continuity to ground is found the stator is bad(a very slight grounding will cause the battery to discharge slowly while riding).A good rule of thumb has been if the battery goes down while the bike is parked (not being used) look at the rectifyer.If the battery goes down while riding,look for a no charge or stator short. The magnet in the rotor is another story.If the magnets get weak(and over many years they can)the system just can't charge enough to keep up.No reliable tests have come from honda to test rotor magnet strength.We have had to rely on comparrison to a known good unit or common screw driver test.The screwdriver test is you take a screwdriver and hold the end near the magnets and see how fast and hard the screwdriver is pulled to the rotor.Compare this to a good one and remember the feel.Sounds cheesy but works.Remember that these little bikes didn't break even(charge) till almost 5,000RPM.So when one rides these bikes on the street it is a constant battle to remember to use the brake light and the signal lights with care(they draw more than the system puts out).Back in the 70's I always had people who complained about low batteries on these bikes.So I started riding o demo back and forth to work(60miles a day) for a month to see if I could duplicate the problem.I could,by setting at a stop with the brake applied,or sitting at a light with the brake appied and the signals on the battery would be low in no time.I tried to educate the owners on battery life and how to manipulate the system to keep the battery up.Some did good and others didn't.I used the demo for two weeks and had no battery problems. Anyway I hope all this has (or will) help you with your bike.

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07-23-2012, 09:17 PM	#3
scrambler Motorcyclist Join Date: Jun 2011 Posts: 9	Thanks Doug for the pointers. I will have to figure out how to test the output on the stators per your directions and see how it does. I should've mentioned that this bike is actually a 125 thanks to a bore job/bigger piston head. I also discovered today that my tail light bulb was actually a 12 volt so I bought the appropriate 6 volt replacement. I'm wondering if trying to find LED light bulbs for the tail and turn signals might help. I just want to be able to drive across town without getting myself stranded.

08-28-2012, 06:36 PM	#4
skyhawk Verified Join Date: Jun 2012 Location: Mineral Virginia Posts: 47	A LED will work for your brake and tail light, it will not work for your blinkers without modification. SuperBrightLEDs.com will most likely have something that will work for you at a reasonable price. I put blue leds in my old yamaha instruments and it looks pretty cool at night. There is a way to use LEDs for the blinkers but your existing relay will not work because it works off of resistance, and leds basically dont have any. If you like I can seend a link from a diffferent board... they are doing it on 12v newer bikes.

05-01-2013, 02:26 PM	#5
letsgocouchman Motorcyclist Join Date: May 2013 Posts: 11	i had the same problem on my 71 CL100. never did find the problem though. ended up selling it before i had the chance.