dx500 idles great but won't accelerate
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  1. #1
    Junior Member Dne007's Avatar
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    dx500 idles great but won't accelerate

    Hi, I'm dne' I'm working on my brothers 80 CX500. When he bought it, it idled great, but wouldn't accelerate/cough sputter but never achieve over 2-5k rpm. I contacted Chris at Sirius and bought all parts to overhaul the carburetors, new plugs. The old spark plugs were black with soot, gas fouled. After all the work of cleaning the carbs, and new parts, the bike pretty much does the same thing. It idles great, but rolling on the throttle~ it's rough and difficult to get it to go 'vroom'~! He's getting new gas for it because I said so. lol I thought sure the carb overhaul would take care of it as the carbs were missing the adjustment screws under the carbs. Compression with a warm engine, throttle wide open will produce about 150psi from about 10 revolutions.

    Removing the spark plug wire one at a time while running, wire on the left side the engine will drop in rpm greatly as I would expect, but removing the plug wire on the right side almost makes little difference, actually idles better with the Right plug wire disconnected from the spark plug. I could really use some advice about now. I had searched the forum and seems like I should replace the ignition coils/plug wires? But I don't see where to buy them.
    thanks!
    dne'

    these are kind of older pictures now. The carburetors before overhauling them was just showing the adjustment screws missing.
    http://cx500forum.com/forum/asset.ph...5&d=1493340329

    http://cx500forum.com/forum/asset.ph...5&d=1493340036
    Dne'

    '80 CX500 cafe racer (current project)
    02 Derbi GPR 50 (current project)
    73 Triumph TR6
    67 Mustang coupe
    59 Chevy apache
    03 KTM 525 supermoto
    05 DR250se


    www.Classiccarsandtools.com

  2. #2
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    first try new plugs

    then better do the stator test to rule out stator and pickup issue

    tName:  stator test.jpg
Views: 68
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    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


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    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

  3. #3
    Junior Member Dne007's Avatar
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    Thank you

    Thank you, I will do that soon!

    Quote Originally Posted by murrayf View Post
    first try new plugs

    then better do the stator test to rule out stator and pickup issue

    tName:  stator test.jpg
Views: 68
Size:  74.3 KB
    Dne'

    '80 CX500 cafe racer (current project)
    02 Derbi GPR 50 (current project)
    73 Triumph TR6
    67 Mustang coupe
    59 Chevy apache
    03 KTM 525 supermoto
    05 DR250se


    www.Classiccarsandtools.com

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  5. #4
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    Sounds like weak spark and mostly on the right cylinder. To test swap the wires and see if it changes.
    AKA Eric
    1982 GL500 Silver Wing Interstate
    I would have no time to ride if I had to do all the routine maintenance and cosmetics suggested, I chose riding (within my reasoning).

  6. #5
    Junior Member Dne007's Avatar
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    Thanks Eric, just a quick question, I went to remove the spark plug wires, do they just pull out, or unscrew? I don't want to ruin them, even if they're bad. and if the wires prove to be bad, where do I purchase plug wires?
    Dne'

    '80 CX500 cafe racer (current project)
    02 Derbi GPR 50 (current project)
    73 Triumph TR6
    67 Mustang coupe
    59 Chevy apache
    03 KTM 525 supermoto
    05 DR250se


    www.Classiccarsandtools.com

  7. #6
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    I'm not familiar with this bike model but most bikes run 2 coils per cylinder or 2 per 4. I'd suggest swapping them at the coils, they won't reach from the heads without being a major headache if that's what your thinking. You'll have to pull the tank but you can gravity feed the carbs with anything. I "IV" dripped a 79 Honda civic wagon for 7 miles and got it home.
    AKA Eric
    1982 GL500 Silver Wing Interstate
    I would have no time to ride if I had to do all the routine maintenance and cosmetics suggested, I chose riding (within my reasoning).

  8. #7
    Senior Member
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    You cant replace the plug wires on a cdi bikeYou replace the coil with attached wire
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

  9. #8
    Junior Member Dne007's Avatar
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    Well, I bought a set of used ignition coils/wires from ebay. So, we'll see what happens. Thanks!

    Quote Originally Posted by murrayf View Post
    You cant replace the plug wires on a cdi bikeYou replace the coil with attached wire
    Dne'

    '80 CX500 cafe racer (current project)
    02 Derbi GPR 50 (current project)
    73 Triumph TR6
    67 Mustang coupe
    59 Chevy apache
    03 KTM 525 supermoto
    05 DR250se


    www.Classiccarsandtools.com

  10. #9
    Junior Member Dne007's Avatar
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    Numbers 3 and 7 did nothing on my digital VOM. The battery was still hooked up but the key wasn't on; so I didn't know whether to have the battery connected or not? It's easy enough to do. I'm not an expert; more like a sub novice when it comes to measuring ohms, but I feel I got the correct readings from meter.
    But I don't know how to translate the findings? I feel like I need to follow some of the wiring to make sure it's connected.


    1) RH low speed coil 118
    2) RH High speed coil 102
    3) RH Adv Pulser didn't register
    4) LH low speed coil 118
    5) ground
    6) LH high speed coil 98
    7)LH adv pulser 0 nothing registered
    8) source coil high speed .451
    9) source coil low speed .357
    Dne'

    '80 CX500 cafe racer (current project)
    02 Derbi GPR 50 (current project)
    73 Triumph TR6
    67 Mustang coupe
    59 Chevy apache
    03 KTM 525 supermoto
    05 DR250se


    www.Classiccarsandtools.com

  11. #10
    Senior Member
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    you have some stator issues and maybe headed to a rae san or maybe ignitec

    plug your results in here

    https://motofaction.org/motorcycles/...l/stator-test/
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

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