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Discussion Starter · #1 ·
Hi
Recently the Starter motor on my 1972 CB450 stopped working mid crank. The solenoid clicks but the starter motor doesn't turn.
I getting 12.4 volts from the battery to the solenoid- and out from the solenoid when the button is pressed. I also get 12.4 volts at the starter motor end of the cable when the button is pressed. When I jump the starter motor directly from the positive on the battery with jumper cables in turns as it should. When I reconnect the cable to the starter motor and press the button it doesn't turn- even though I get 12.4 volts out of the cable. What am I missing??? Any help would be greatly appreciated.
Thanks!
 

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IMG_6894.jpg Try cleaning it.. the two screws and two 10mm bolts and it will come off. Once removed, lightly TAP the end cover off.. there you will see the brushes and where they make contact. The brushes wear, and become "shorter" and the springs don't have much "pressure" to push the brushes..
I discovered this about a year ago.. I cleaned it and reassembled, just this weekend it acted up again.. sounded like a weak battery and dragging .. this time I added material to the back of the brushes to aid with the spring friction..
Knowing I had done this recently done this and it came back I reassessed since I noticed a lot of "powder" (brush material). I decided to replace them this time thinking the brush material appeared to be "breaking down"...
Got a "kit" online (e-*ay).. $30 .. a bit pricey.. but I know I won't have to deal with it again.
 

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Discussion Starter · #3 ·
Thanks for the reply. The starter motor turns strong when jumped directly from the battery so I don't think cleaning it will help as I know it already works. I am getting 12.4 volts to the cable when the button is pushed but the starter motor wont turn when the cable is connected. It makes no sense to me as power goes to the cable when disconnected from the starter motor but the motor doesn't turn when reconnected.
 

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My mistake... I was half asleep last night when I replied to this thread..sounds as simple as cleaning terminal ends and possibly a relay (internal) failure.. you may have actuation but not good "contact" inside.. maybe enough to regestered voltage... but not allowing amperage to pass...,think of it like this .. if you measure voltage at a running light it will read 12v.. now look at the wire that carries that 12v.. would u use a wire that size to wire the starter motor??
Someone else here can explain how a ampmeter is used.. I can't.. so I won't..
.... late night post was due to waiting for my new "purchase" to be delivered..got in at 1am.. I'm tired.. but I'm happy!!!
 

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12v does not require much internal resistance to drop the available power. It seems from your description of the fault as though you do have a connection to the starter motor terminal (I assume that is what you mean by seeing 12v at the starter motor) that can deliver a small amount of power (Amps) that will register on a volt meter, but not be able to turn the starter which will demand many amps to turn the motor over. (According to the WSM up to 280Amps maximum, from 35Amps unloaded).

I would suggest taking off the starter motor cable and checking the terminals for corrosion and also checking the solenoid for a good connection when it actuates. Check the resistance of the switching side of the solenoid this should give 0 ohms when it is switched on. If there is a lot more resistance than 0 ohms that will be where the problem is likely to lie. Otherwise it may be teh cable itself. e
 

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Hey there, did you figure out your issues? just a few ideas, how are all your grounds? Is there a clean connection from the starter motor to the motor itself? Assuming so, what about the ground wire from frame to motor?

I'm having issues with my starter motor turning clockwise, instead of counter-clockwise so I'm searching for other posts with similar troubles. Does your starter clutch operate as it should, engage in one way, and not the other? I'm concerned if I even have the proper starter motor to fit, as I've taken it apart several times and seem to understand that it can only go together "one-way" while unable to reverse polarity and switch the motor's direction.. anyhow, hope you figure it out or have gotten it taken care of.

-M
 

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The starter motor on my wife's 450 was having "issues". Took it apart, cleaned it (full of crap).. reinstalled, worked great for a bit.. then the "issue" started again (not starting/spinning). Disassembled again.. and noticed the inside was kinda filled again with crap, not as much, but for the use, it seemed strange. The bike is stored inside....
Did a little more "digging", noticed the brushes were worn, not big deal, but this time I checked their movement in their slots. They didn't move as easy and "contact pressure on the armature also wasn't very firm.. I had to get this running, minimal down time so here was my fix....
I cleaned it again.. and payed attention to the brushes and their movement, making sure they slid easily..ALSO, I added small pieces of plastic (cut bondo spreader) and placed these between the brushes and the springs.. basically adding "material" to the brush and more "tension", in turn forcing the brushed against the armature...
It seems as though the material the brushes are made of are starting to deteriorate... I ordered a new set, havnt had to install them ... YET...
Hope this helps..
 
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