Topic: installed new exhaust, now electric start doesn't work

[francesb]

Hey all,

So, I broke down and paid the car mechanic on the corner $60 to install my exhaust, the old bolts were too stripped for me to remove, and I couldn't drill out the fastener thing on the silencer. So, a reasonable amount of money well spent, bike looks and sounds much better.

Except, now the electric start doesn't work. I don't see anything that appears to be loose. What could he have done? Or is it a coincidence?

[Buffo]

what year/model

[francesb]

pffff.

It's a 73 CB750. .

[Buffo]

have you tried to start it with the clutch pulled in?

[francesb]

yeah, I tried that. It makes a slight almost-buzzing sound with or without the clutch pulled in.

[Jonesy]

Will it at least kick start? Sounds like the buzz from the starter when the battery is tired. (Just narrowing stuff down)

[francesb]

Kicks over on the first try, and the lights/horn are strong. I don't think its the battery.

[Buffo]

I have no Idea of how to fix your problem...

[Bodi]

If it's buzzing from the solenoid switch, there's a bad connection somewhere in the solenoid circuit or the solenoid itself is jammed.
Checking the small wires on the solenoid with a voltmeter will tell you which. If it has about 12V on one wire and 0V on the other when the starter button is pressed but it still isn't starting (turning over) then the solenoid is stuck.
If the solenoid gives a nice clunk when the starter is pressed and the buzz comes from the motor, you might have a motor problem but it could still be the solenoid. Jamming a screwdriver between the two big stud terminals on the solenoid will energize the motor for sure and tell you if it is fine.
The solenoid is serviceable, you can remove and disassemble it. Disconnect the battery first, there's no fuse in the big power wire and it will touch the frame when removed. Clean the contacts - the copper bolt heads and the copper bar contact. Clean and lightly lube the moving parts. Should work.
The motor has replaceable brushes but I've never seen one need them.
I suspect a wiring problem. I don't know why or how working on the exhaust would do that but strange things happen.

[clarkjh]

check the main feed from the starter to starter solenod, should be with the rest of the goodies, (fuses, rectifier, ect).  Sound like there is a short to ground in this wire.  I had the same problem on my 74 550 when I pull the left hand cover to check my oil sensor, and crimped the wire when I put the cover back on.  Also took me two weeks to find the problem.

Hope this helps.

James

[TwoTired]

Could be starter, could be solenoid as mentioned above.
Could also be the push button in the bar control, particularly if the master cylinder has leaked brake fluid into the switch housing.
Does your headlight still function correctly?  The starter and the headlight can be affected with that starter button switch.

[Jonesy]

Kicks over on the first try, and the lights/horn are strong. I don't think its the battery.

Mine did too. I looked at the battery and found one cell low on water. Everything else on the bike worked fine, but it didn't have enough oomph to roll it over.

[francesb]

thanks, jonesdp. that was the problem.

[heffay]

hoooray for jones!!!!!    we love you

[Jonesy]

No prob, glad I could help.

I love it when the cause is something simple- saves a lot of grief!