Topic: 73 cb500

[cornfed89]

Hello all Im new to the forums and recently picked up a cb500 under the assumption it needed a new starter. I picked it up from a lady who had bought it for her BF and they apparently parted ways while she was having it fixed up at a shop for him. Sooooo naturally I spoke with the shop owner who verified all it needed was a starter as he had checked the compression and rebuilt the carbs put new plugs and wires on it etc...soooooo as the story goes I bought a new starter and assembled it put in a dead battery from my 4wheeler and put it in and hooked jumper cables up to my truck now I cant get it started for more than 30 seconds itll backfire and sputter then die. I pulled all the plugs and wires and am getting spark on every cylinder EXCEPT#3 I tried a proven plug and wire on that cylinder and still nothing. Also I noticed that different exhaust pipes heat up differently ex. cylinder 2 is piping hot while cylinder 4 is luke warm. Im at my wits end with this thing it almost seems as if the timing is off or something maybe he didn't sync the carbs after rebuild because the bike needed a starter I don't know if that would cause these symptoms though. when I pulled the plugs cylinders 1 and 3 had unburnt gas in them as well. I appreciate any help with these issues this is my 1st project bike as all my others were always newer and maintenance went as far as oil changes and plugs. However I am looking forward to getting this thing goin and having something different from the mainstream riders. Thanks again for any insight!

[Bankerdanny]

Sounds to me like you need to go through your ignition system.

I would be systematic about it. Start at the points. Check all the connections and make sure that the wires are attached to the right sets. Check the connections at the coil, particularly any bullet connectors. Check for continuity to make sure there are no breaks in the wires. You can remove the plug boots from the wires, trim off about 1/4 inch, then reinstall. While you are at it you can test the resistance at both the plug boots and the coils themselves.

Make sure the point gaps are right and checl the static timing.

[rb550four]

Spring for a battery.

[Honda550k]

You mentioned he replaced the wires. What wires did he replace?

[LesterPiglet]

I would start by doing the 3000k tuneup. Who knows what's gone on before?

[Duanob]

The bike won't run on a dead battery, you need to spring for a new one. before you do anything else.

[cornfed89]

even if its hooked up to a running vehicle? I will go get a battery this evening though and the plug wires and plugs where just replaced and carbs rebuilt. Ive been putting off the points and timing as honestly I don't know how to check it. Ill definatly try a new battery and trim back the wires as stated if nothing else I can take it to my buddies and have the timing checked and carbs synched. I appreciate the suggestions guys if anyone thinks of anything else holler like I said im new to these older bikes but from the looks of things ill be learning a lot 

[Bankerdanny]

Do not hook your bike up to a running car. That is a fast track to a fried electrical system. A car altenator puts out way to much power for a motorcycle system to handle. Jumping from the battery with the car off is fine, but DO NOT use a running car.

Plug wires are not replaceable with stock coils.

[Honda550k]

Check to see if the plug wires are connected properly to the coils. I once got caught on the rain, I next day I go and start the bike one cylinder is misfiring. So I check the connection where the plug wires are to the coils and there was water build up causing it to short.

I have Dyna coils and dyna plug wires.