81 CB750K

[jbrightwell]

Hello to all!  Im new to CB750's but bought an 81 K model anyway.  The new starter relay (solenoid) that I bought has a "B" at the 10 oclock position and an "M" at the 2 oclock position.  The way the old one was, the "M" terminal went to the battery and the "B" terminal went to the motor, but the old one was not labeled.  Does this sound right or was it hooked up backwards?  B for battery and M for motor?  I dont want to fry the thing .  Thanks, all help is appriciated - JON

[jbrightwell]

Well - seems like a lot of questions have been answered on this forum and I sure learn a lot by reading them.  Someone must know the answer to my question about the starter relay.  In the picture the wire going to the positive side of the battery (red) is connected to the terminal marked "M", and the other wire (black) is connected to the terminal "B".  All I am asking is - is this correct or backwards?  Thanks - JON

[shinyribs]

I would say that you are correct with B for Batt and M for Motor. But I've never seen a solenoid that is not reversible anyway. You're good to go.

[jbrightwell]

I was wondering about the reversable possibility.  I sure thank you for that info I was a bit worried about frying something.  The whole thing was that the last owner lost the key and instead of buying a new key or even a complete switch - he hot wired it with a toggle!  Stupid is as Stupid does...

[Cabreco]

If the wire polarity is accidentally reversed, nothing is damaged.

[sgtslag]

I was an Electronic Technician for 3+ years (Computer Technician for 22+ years).  To answer your question, a solenoid, which is what a relay switch is, has no polarity at all.  Essentially, it is a coil of wire, which, when power is applied, generates a magnetic field, closing a set of contacts (which delivers power to the Starter Motor, in this case)

Sometimes manufacturers will mark the contacts with different letters, or +/- (users can panic if they don't know which wire goes where, so this is done as a little bit of handholding...), but for a solenoid, this is irrelevant.  Regulators/Rectifiers are a different animal, and their contacts cannot be reversed.  Cheers!

[jbrightwell]

Ive got my new ignition switch installed.  We know the black and red wires to the solenoid are on.  I have power to the side with the wire to the battery of course.  But I have no power on the other side of the solenoid.  There are four wires that plug in at the solenoid, I plugged those in as they were on the old one but that might not have been right.  Is there a specific spot for each of those 4 wires?  There is a 20 amp fuse on there and its good.  Bad solenoid maybe??  Thanks again all.  JON

[jbrightwell]

I should have mentioned this is an aftermarket solenoid which I know is a no-no but it was available.  It definitly makes a difference which wire goes where on this one.  Maybe not so much for the solenoid itself as sgtslag mentioned here, but for those 4 wires that plug into the solenoid it sure does.  I took it off and hooked up everything bass ackwards and the beast is ALIVE!!  OK not running but the old 4 turns over and all four new plugs have spark!!  This might not be much of an epic moment for all of you but for me its major.  I can start putting clean carbs back together and then clean out the old gas tank.  Thanks all!

[Piute]

  I'm not much help with d.o.h.c. ,But you keep working with the manuel you'll get it.
                   Many here have those type of engines, Welcome ..Have fun..piute..