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Starting my 1981 Honda CB750C

2284 Views 10 Replies 2 Participants Last post by  esspee51
I am trying to get my Honda CB750C started after many years in storage.I don't think it had been serviced for storage but just parked in the garage. The owner died and I inherited it.

I have removed and thoroughly cleaned the carbs, changed oil, replaced hoses and coil pack. When trying to start it only one cylinder fires.

Any suggestions would be appreciated.

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Well, it's too new for points so that's out. Have you tried new plugs? How far did you disassemble the carbs? Check the compression in the cylinders that aren't firing.

I removed the carbs and completely disassembled and cleaned. I haven't tried plugs or wires yet but that is next. compression is good.

Thanks for the response.

Let me know what you find out. See if the other cylinders are getting spark.

It is sparking in all cylinders, the spark seems a little weak though. I will be trying new plugs and wires so I guess we will see whwt happens.

I'm not sure if I have all the fuel lines hooked up right, when I brought the bike home most of the lines were not connected or missing completely.

Can some body help me out with a diagram of some kind?
There should be only 1 fuel line, it's probably 5/16" or 3/8" diameter. The other is probably a vacuum line that opens up the fuel valve. One thing that will cause a weak spark on a bike is a low weak battery or a dragging starter. It takes away energy from the battery tryin' to turn it over that it doesn't have a enough left over for a hot spark.
Starting CB750C

I have a coil pack containing two coils with two outputs each. Is there a certain sequence they fire? I believe the firing order is 1-2-4-3 is that correct? What order should they be connected to the coils.

Starting CB750C

Does anybody know of a site on the internet where I can find a diagram or picture of the fuel and vacuum lines on the carbs?
You got the firing order right. I don't know of any online fuel and vacuum diagrams, sorry. I would pick up a shop manual for the bike if I was you, even a Clymer or Haynes manual would be a huge help.
Thanks for the information. I have a clymer manual, but of course it has everything except what i need at this point. I plan on checking the library this weekend.

Thanks again fo all your help.
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