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I recently bought a 1975 Honda CB 500T and have been putting some work into it. Left cylinder was not running correctly and overall the bike was having issues running. I cleaned and rebuilt the carbs, changed out spark plugs, put in a new battery and it runs much better now.

Known facts related to the bike-
1. Spark plugs keep getting carbon fouled(replaced them twice since I got the bike a month ago- using NGK B8ES's)
2. Bike occasionally idles extremely low and then wants to die

I am thinking the two issues may be related(too much fuel?), someone correct me if I am wrong please! I am very new to motorcycles, but I am handy and I can do most of my work on my own. How do I go about adjusting the Fuel to Air ratio so that the bike doesn't overuse fuel and foul the spark plugs? Any help is appreciated!

Side note, I purchased a Regulator/Rectifier from Common Motor (to replace the separate regulator and rectifier) and it didn't fix my charging system. Is the next step to check the stator coil? Not very familiar with how to do that or where the connectors are on the bike- any help with that is appreciated to. Thanks in advance!
 

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Air/fuel mix is the little brass slotted adjuster on the bottom side of your carb near the cylinder head.Turn in to lean, out to enrich. You can download the FSM in the manual section of the forum. Check floats and get a vacuum sync to set the carbs.
 

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First thing first. Do you have the Honda Factory Service Manual? If not then download one.

https://www.hondatwins.net/forums/5...uments/42637-cb500t-honda-service-manual.html


I would suggest open up your stator and inspect all the windings and wiring. I had a charging issue on mine as well and it turned out that one of the 3 wires from the stator was pinched on the engine casing and exposed some wire and shorted out. I replaced the wiring with new wires and shrink wrapped everything and it's been as good as new.

As for your carbs. Did you adjust the air/fuel mixture? How many turns out?
 

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A slowing idle and carbon-fouled plugs both point to very rich; if you set the float levels correctly, make sure they are not sinking.

Please describe the problem you have with the charging system: Voltages at different rpm would help.
 

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Keyster jet/needle kits can also cause it to run rich. If you can find OEM it is best to use them.
is it all stock or is the exhaust or airfilters changed or modified?
Makes sure choke is off and not moving.
Make sure carb adjustments are made on a hot engine.
is idle set at 1100? (1000-1200)
as stated check float adjustment and for leaking floats and use FSM for all initial carb settings.
 
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