1981 cb750k starting issue.

[Piute]

        Sorry late looker Mine was bad too,(stay away from d.o.h.c. advice)
       but was the 1st thing I checked and left off the 1 in and on the lever only,
      still has to be in neutral to start I like knowing that when I kick it that it's not
      going to jump or fall due to being in gear,

[barelycompetent]

I thought about that shiny, and Piute I also thought about bypassing it and moving on lol.  My chopper has to be in neutral to start it so Im in the habit of making sure Im always in neutral when I start it, so it wouldnt be a problem with the honda.

[Todd4077]

I just found this forum and registered.

Off the bat I am guessing a bad solenoid 1st up.  Another probable and likely culprit - the starter. I also read about the starter buttons being a problem and based on a couple of starts early on have that in mind too.

Where can I get a solenoid and starter for my year if if comes down to those? I see pre 80s in the few searches I've run. Automotive I am fairly good with, mostly Jeep but motorcycle stuff is new and I thought I'd learn.

The 81 CB750K I have is my first motorcycle and I finally got it home after it sat at my parent's place a couple hours away close to where I found it. Only 5900 on the clock.

Anyway it is in good condition. It was prepped for storage just before the owner died years ago. It was sold to me by a brother of his. People who know a lot more than me that have seen it like it.

I put a fresh battery in it after getting and it cranked right up after off the trailer a couple months back. It has a few other minor age related problems that were mentioned and I will get to them. After that it sat in a building but got started every couple of weekends.

Yesterday I put a fresh charged battery and it was slow to spin over although all the other electrical came up. Then it flatlined electrically. For a second I thought I smelled something which was not quite a burned electrical but kind of odd. No smoke or anything else obvious. It turned late so I rolled back inside.

I hooked the battery in this evening and still flat. Wiggling the area around the solenoid and reseating the connector got power restored. However the starter is slow but constant.

How much surgery is it to pull the starter to bench test assuming solenoid and switch test good? Evenings this week I will clean contacts/connectors and do some more tracing and testing with a meter and light. Fuses look ok. I will put fresh ones in, got plenty of new ones.

Here it is from a month or so ago idling.

https://www.youtube.com/watch?v=cfp_ixZlB-M

The tank is supposedly wrong for the year.

[Rodgil]

Hi Todd, It is very easy to remove the starter. That will give you a chance to make sure all connections are good. Download the FSM (Factory Service Manual) from the link on the home page. It is excellent (unlike some) and will tell you everything you need to know.

[Todd4077]

A new solenoid finally arrived after being lost in never-never land of the local UPS store which is another story. It's Honda OEM.

Mucho better all around. Finally ran for the first time in weeks. Electrical is stable so far.

Carbs are next. Not much of a carb rebuilder in even automotive. Seen a few supposedly professional rebuilt ones on Ebay and they are under watch. Tires are needed, the ones on it are dry rotted from sitting in storage in the previous owner's building.

I have front brakes now. I was looking and working in the wrong place mostly.

A semi-retired guy friend of one of the neighbors saw me working on it and dropped by. He had a few vintage Hondas. I told him the front brake saga. I really wasn't planning on doing front brake stuff late last evening but it happened.

After trying some of the usual caliper stuff I read about, he had a different idea and no telling when I would have thought about it.  I also found out that I knew about motorcycle brakes than I thought. I took out the collapsed rubber diaphram/seal and cleaned out the chamber.

After he asked a few questions and looked at for a minute, he noted that one of the two holes never opened when cycling the lever. A tie wrap from a bread loaf and some poking yielded many air bubbles.

To make a long story short, the brakes took a bleeding and I have a firm brake. If it weren't for him, no telling how much time and money I would have spent fighting it. A mechanic could have ripped me and I doubt I'd known.

[Re-run]

There is lots here about the brakes. The hole he was talking abotu is a common spot to plug up. It just happens and a small poke is all it takes. However, removing the piston in the master should be done every so often to clean the corrosion out of there. There are lots of little tricks over the years with these brakes.