Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.
Sticking starter
Q: The starter won’t disengage on my Honda CB550. The instant you turn on the key, the starter motor starts to turn. What’s wrong? Is it my starter button? — Kurt Limesand/via email
A: It may be the switch in the handlebars, but there is also a strong possibility that you have a stuck starter solenoid. I’d start by disconnecting the thinner signal wires to the solenoid and turning the key on again. If the problem disappears, the starter button circuit is shorted out. If the problem persists, your starter solenoid is stuck and will need to be replaced. MC
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I had the same problem on my CB400F which has a similar switch to your CB550. The button toggles between turning off the headlight and then engaging the starter motor. When you release the switch the headlight turns on and the starter disengages. The plastic housing which holds the pivoting contact can crack, which could explain why the starter keeps running if it's not the solenoid. Check out this thread on SOHC/4, the designer has made a replacement part available on Shapeways. http://forums.sohc4.net/index.php?topic=163170.0
I had the same problem on my CB400F which has a similar switch to your CB550. The button toggles between turning off the headlight and then engaging the starter motor. When you release the switch the headlight turns on and the starter disengages. The plastic housing which holds the pivoting contact can crack, which could explain why the starter keeps running if it's not the solenoid. Check out this thread on SOHC/4, the designer has made a replacement part available on Shapeways. http://forums.sohc4.net/index.php?topic=163170.0
If it doesn't crank till you turn the key it can't be a stuck solenoid as it would crank as soon as battery was connected if solenoid was stuck