Topic: New Project CB750A - where to start?

[nhixson]

I was just given a 1977 CB750a from my father. He bought it a few years back with the intention of restoring the bike. He has several other projects going on right now and does not have the time. Long story short, the bike is now in my garage. It does not run, but the engine is not seized up. It needs quite a lot of work. I would love to restore this bike to its former glory, but am feeling a little overwhelmed by the amount of work involved. I guess I am looking for a place to start. Any suggestions?

[raymond10078]

Here's what I did:

• First, I removed the plugs and used a battery charger to spin the motor over verify that I had oil pressure.
• Then, I moved on to check compression.
• From there, I checked the points - made sure I had spark.
• Then I tried to "start" using starting fluid.
• If the engine tried to start or ran for a short while (no real money spent yet), then I removed/rebuilt the carbs, fuel system clean/flush/install filter, new battery, 3,000 mile tune-up, etc.

Download the service manual from this site.  Lot's of folks here to help!

[nhixson]

The carb is off the bike, it needs to be rebuilt. My father nearly had the bike starting about a year ago, but the carb was all gunked up. I have 4 rebuild kits, but have yet to start on rebuilding it. MY concern is the electrical system. The previous owner installed a faring on the bike to make it look more like a Goldwing. My father took it off. The front of the bike where the headlight goes is a mess of wires. I know engine people that can help me with mechanical issues, I know body people that can help with that. The electrical issues have me a little concerned. I think that I am going to rebuilt the carb, charge the battery and see if I can get it to start. At least that way I'll know if there are any mechanical issues with the engine that I need to address.

[dave the welder]

somewhere there is a place to download wiring diagrams for your bike.everything is color coded for each circuit.just take your time and all will be good

[raymond10078]

Download the schematic (see top of this web page).

All of the wires are color coded - and it really isn't hard, but patience is required - just do one wire at a time.  When going from wire to wire - just determine where the wire comes from (which "loom").  Some will come from the main harness, some from the speedo, some from the gear indicator, some from the right control, etc, etc.

From the schematic - the connections circled are in the headlight bucket (the main two plugs are their, too).

[nhixson]

Ok, so I have the wiring schematic, now for my next question. Im considering tearing the bike down to the frame and rebuilding it from the ground up. I'm not really in a hurry to get it running, so I have the time to do it. Is this an advisable course of action? The logic behind this is that completely stripping the bike will give me a better understanding of what needs to be fixed, replaced or refinished. Any suggestions would be appreciated.

[dave the welder]

personally I would get it running to make sure everything works.then if the mood strikes tear it down.this way you will know it worked before you tore it apart so it should work after reassembly

[Grnrngr]

Making it run first will give you a much better idea of what works, what doesn't, and what needs to be fixed. If I had torn mine apart and then put it back together first, I still would not have known the trans was bad, so, while I do need to pull the motor and rebuild the trans, the top end is good, and there is nothing wrong with the rest of the bike that requires a complete teardown. Best of luck, and post some pics!!

[jonnycakes]

If it was my  bike, I would rebuild the carbs, get new plugs, points, condensers and battery. Change the oil and filter and then ride it.  A restored Hondamatic is worth 3-4 thousand tops. 

[JimS63]

I agree with jonnycakes, if you tear it down and rebuild it completely, you may have way more money invested in the rebuild than what the bike is worth. Just get her running safely and ride it!