Question about 1981 Honda CX 500 B

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Hi, This is probably a simple question but it has me baffled. I bought a cx500 1981 custom last week and I have had a couple of teething problems. The main one being that she looses power - at full throttle she only goes at about 80kph. One of the spark plugs had black deposits, as I understand, a problem with air/fuel mix. I have changed the spark plugs but still have the same problem. I have been stripping down the twin carb to clean today, and have noticed that one of the needle jets(piston needle jet?) is loose and the other is rigid. There was some dirt in the carb, but the spark plug that was black matches the same side as the loose needle. Could this be the problem? what would be the solution? I have tried doing the needle set screw up but it won't tighten any more. Is this problem normal? Is it a problem? Any help would be gratefully recieved.

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  • sacha_marles Sep 26, 2009

    Hi, what about the needle is this normal?



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You definately have a fuel problem .
clean your tank first as deposits in the tank might have made way to the carbi .
the fuel/air mixture is one thing but your bike may have also oil burning issues .
try first by making sure the carbies are clean , fuel tank clean , the air mixture adjustment is tricky but usually screw the air mixture screw on the carbi all the way in and undo it 1.5 turn back and no more .
try that first and see how you go . the vaccum menbrane in the carbi may be defective too and may have to be changed .
have a look at all that and see how you go

Posted on Sep 26, 2009

  • chris Sep 26, 2009

    the needle will always move slightly and i would not worry about it .

    try all the previous ideas that i gave you as the needle will travel into a seat and will not affect the performance of the bike .



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