Topic: Circumstances Have Caused Me To Diviate Slightly From My Previous Course

[bill440cars]

        Several of you have told me that I need to concentrate on ONE bike at a time and quit trying to work on several at one time and you all are right, of course. However, this deviation is quite warranted. You see, I now have in my hands, a clear title for my 80' CB750K and it being the most complete and (hopefully) the easiest to get going properly, I need to get it on the road. All of a sudden, it won't crank over using the electric starter (and that' all it's got). It will still need a paint job, but I mainly want to get it running and worry about a paint job later on toward the end of the summer. I also need to change the fork seals and work on the front brake caliper (it seems to hang now and then). Now, I know that this is one of those DREADED DOHC jobs and that is why it's here in this forum. After I get these things cleared up on this one, then I'll get back to the 74' CB450K7 and actually start a thread on it. Now, I DO have a manual on this bike, but any input that any of you might have that would help me to get this bike squared away sooner, would be appreciated.

                                    Later on, Bill      

[kghost]

If you need a starter bill I may have one in the dead engine pile.

I have about 3 -5 of the DOHC engines that I wound up with in a "NO you can't take just the SOHC engines you have to take them all" deal

[Aaron J Williams]

I would begin at the starter solenoid and check for power. If the big cable from the battery has power then check the small power wire that activates the solenoid while pushing in the starter button. If you have power there then check for power at the starter. Also, there is probably a switch at the clutch lever that won't let the starter spin unless the clutch is pulled in and/or bike is in neutral. I think that switch controls a little safety interlock box which actually powers the solenoid. Best idea is to sit down with your wiring diagram and trace out the starter circuit so you can figure out how it works. Then you will know where to test the circuit to find the failure. Corrosion in connectors and switch contacts is pretty common and can cause your symptoms.

[bill440cars]

If you need a starter bill I may have one in the dead engine pile.

I have about 3 -5 of the DOHC engines that I wound up with in a "NO you can't take just the SOHC engines you have to take them all" deal

          Hey Tim, glad to know that one of my "Brother's" has  pssobly what I might need.   I'll be talking to you.

                                   Later on, Bill    

[bill440cars]

I would begin at the starter solenoid and check for power. If the big cable from the battery has power then check the small power wire that activates the solenoid while pushing in the starter button. If you have power there then check for power at the starter. Also, there is probably a switch at the clutch lever that won't let the starter spin unless the clutch is pulled in and/or bike is in neutral. I think that switch controls a little safety interlock box which actually powers the solenoid. Best idea is to sit down with your wiring diagram and trace out the starter circuit so you can figure out how it works. Then you will know where to test the circuit to find the failure. Corrosion in connectors and switch contacts is pretty common and can cause your symptoms.

          Thanks for that Aaron, you are right. I DO need to get the wiring diagram out, check it out real well and start check this sucker out. Appreciate your input on it too! Little rusty on the "Troubleshooting" part, but I've got to get after it though.

                             Thanks again,  Bill

[bryanj]

Bill the starter circuit is very similar to the SOHC with safety interlock. just check out all the connections/switches in the system.
Dont remember any particular problems with starters, just alternator brushes.
Somewhwere i have the genuine honda book for that, let me know by PM if there is any particular info you need and i will scan and email---to big to do all of it!

Nother thing is really dont like gas thats been stood about, any more than 5 days and you have to drain the carbs

[bill440cars]

Bill the starter circuit is very similar to the SOHC with safety interlock. just check out all the connections/switches in the system.
Dont remember any particular problems with starters, just alternator brushes.
Somewhwere i have the genuine honda book for that, let me know by PM if there is any particular info you need and i will scan and email---to big to do all of it!

Nother thing is really dont like gas thats been stood about, any more than 5 days and you have to drain the carbs

           Thanks for that Bryan, I haven't had the chance to get into it just yet. Trying to get me some work space in my garage  and it ain't easy. We've been having quite a bit of rain in the past few days (or so) and I have to move some things out of th garage in order to do some rearranging. If I can't figure out the problem and feel like I need that info, I'll let you know. It's nice to know that that particular info is available too! I appreciate it.


                                  Later on, Bill  

[tbpmusic]

Bill -

I have a '79 750K sitting in my garage (tailend is slightly different than yours). I unloaded it from the truck a year ago and haven't touched it since. Clear title in my name. It's almost complete, but not even roadworthy.
I have no idea why I picked it up, as I'm more of a Twin guy. I guess I thought it was historically significant, first of the DOHC Fours, a line that continues even today.
I'd sell it in a heartbeat if I could find anyone who wants it (apparently no one but me).

Anyway, though I am NOT knowledgeable about the DOHC Fours in particular, I have been hanging around people who are.

The good news is that there is big-time interchangeability between nearly all the DOC Fours of that era, regardless of engine size. Guys swap out running gear/body stuff all the time - plenty of cam-swapping and engine stuff too.

The "bad" news is that I don't know anything about them, really, so I'm not much good to you. I do know it's a BIG Heavy engine, compared to what I'm used to, you need a rolling floor jack to get it out. Doesn't seem particularly user-friendly to me, in a fix-it context. PIB bucket and shim type tappets. No kick start, as you noted. Basically 450 carbs with a whole bunch of crap grafted on to make them work worse.

bill2