need help with a 70's cb550. can help? come on in...

NYSpeed Automotive
1

my roomate bought a ratty old flat black 70’s (not sure exactly what year) cb550 last summer. it was a fun bike to scoot around on and ran fine.

the battery died so he charged it off of his car. he hooked up cables and went inside. he came back out 15 min later or so to find that the cables had slipped, and the power was grounding out on the frame. not a good look.

i know absolutley nothing about motorcycle charging systems. is there a main relay or somethign he could have fried? the bike wont even hold a charge now…

any ideas? thanks guys

2

Will it turn on at all? Any indicator lights? Why was the battery dead in the first place? Did anything smell like smoke?

It’s not uncommon for the alternators to go on them. I had to replace the alternator rotor on my '81 CB650. What I’m getting at is if the only problem is that the battery won’t hold a charge then the problem might just be a dead battery and/or alternator.

3

he was jumping it because he hadn’t ridden it in weeks. and he said he has tried to jump it again and no lights at all.

fry how hard is it to swap an alternator on one of these? and how much is the part? ive done alts on tons of cars, but never a bike…

4

jumping a motorcycle battery with a car battery = not good. the bike battery is more than likely shot.

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IIRC (And it’s been about 10 years) you don’t take off the whole damn thing like you do a car. You’ve got the rotor, which is basically a big magnet, spinning inside the stator, which is basically a coil of wire. IIRC I took the cover off, pulled the stator off, and had to use a pulley puller to take off the rotor. Then got a new rotor for $80 from somewhere in Ohio or something. I think it’s supposed to be pressed back on but I had good luck with a hammer and a block of wood. Fuck it’s been a long time.

The CB550’s a 4 cylinder right?

6

So he had lights, then came outside to a sparky mess, then no lights?

But start with checking all the fuses. Fuse panel should be under the seat. There may be a voltage regulator/rectifier under a side cover worth smelling for that burnt plastic smell. Look around for relays under the side cover too. Take a look at the battery too. Is the fluid level in teh cells even?

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fry saved me from typing a lot here… good times

what he said… check the fuses too… it might be something as simple as that…

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Jumping off of a car battery is fine if the car is not running. I’ve done this several times and never had a problem . Seems like fry covered what to check already, if you need a hand checking it out post up and I may be able to assist.

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TEST BEFORE YOU REMOVE
get a DVOM and test the stator to see if there is any issues with it.
also you could have toasted your regulator, as it is in a different spot if i am correct

check the stator for resistance
do a diode check on the regulator should have flow one way/ flip the leads should have nothing the other

11

LOL oh les beast :pat: