Re: CB750K Starter Button Fix? (right hand switch)

Posted by LukeM on Jun 16, 2010; 7:49pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/CB750K-Starter-Button-Fix-right-hand-switch-tp893333p900815.html

I took a look at the FSM for 79-83 CB750s, and on page 238 of that PDF it shows a DPST switch for the start button.  That means a single pole momentary switch won't work.  It looks like one half of the switch energizes the solenoid, and the other half supplies power from the battery to power the solenoid.  You'll also see a 30A fuse in line with the start switch.  Might be overkill, but they used that value for a reason.

Engaging the start switch appears to get 12v from the battery, so it'll loop through the switch, provide power for the solenoid, and finally close the low-current side of the solenoid.  This engages the high current side from the battery to the starter, and from there, things go whir and hopefully VROOM until you release the switch.

Either that, or it's all magic somehow.  I'd feel safer just getting the appropriate factory switch from the dealer, or EBay, and using that. Less wiring and modification, and they've done the engineering already.

Luke M