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Carb adjustments

Discussion in 'The Garage' started by ExSquid, May 2, 2019.

  1. ExSquid

    ExSquid XS650 Member

    Greetings my fellow XSers. I'm really happy to find this site.
    So here is the problem. I put on a new coil, wires, plugs. Rebuilt the carbs after a long Wisconsin winter. I was trying to adjust the air/fuel mixture. I started the bike, warmed it up and pulled the left plug wire. I went to adjust the A/F mix and the engine didn't shut down when I turned out the screw all the way. Put the wire back on, readjusted the screw to 2.5 turns out from bottom. restarted the bike and pulled the right plug wire. Engine dies. Another half turn out, plug wire back on, start engine, right plug off, engine shuts off. I have spark at the plugs. So I think its the pickup coil but I'm not sure. I don't know if there is a procedure to test it. I guess it doesn't matter because a pickup cannot be found, ANYWHERE!
    PLEASE HELP!!!
     
  2. grizld1

    grizld1 Grumpy old man Top Contributor

    Welcome, Squid.

    If the motor doesn't respond to fuel screw changes it's often an indication that a float or float valve is defective. There are two OE ignition systems and many aftermarket ignitions found on XS650s, and 5 different carburetor designs. We'll be glad to help you if you'll help us with a bit of information. BTW if your bike has an electronic ignition you should never pull a plug cap on a running engine. If you click the Tech button and scroll through the menu, you'll find links to free downloads of the XS650 Garage USA Carb Guide and factory parts and service manuals.
     
    MaxPete, TwoManyXS1Bs and Jim like this.
  3. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    First off.... welcome sailor. ;) You didn't say what iggy sys you're running.... but all electronic (you mentioned pickup) systems I'm aware of for the XS use the same pickup to fire both cylinders. So if one cylinder runs, you can rule the pickup out right off the bat. You had the carbs apart. Check there. And.... you replaced the coil wires..... check them.
     
  4. ExSquid

    ExSquid XS650 Member

    Thanks for the quick response.
    Okay, I will pull the carbs again and dip them in my ultrasonic carb cleaner. So what do I look at to know what OE ignition system? All kits I've gotten for the carbs have been the 34 Mikunis. The only reason I pulled the wires was that the Clymer manual said to.
     
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  5. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Give us some pics of the iggy system and the carbs.
     
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  6. ExSquid

    ExSquid XS650 Member

    Thanks Air Force. I'm happy to join.
    As far as I know, I'm running the stock, standard ignition from 1981
     
    Jim likes this.
  7. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yeah.... ex flyboy here... :rolleyes:
    The stock TCI coil doesn't have replaceable plug wires. So at minimum you prolly have an aftermarket coil... I'd look deeper if I were you.
     
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  8. grizld1

    grizld1 Grumpy old man Top Contributor

    Re. pulling wires, US models of the XS650 used breaker point ignition up to 1980, and that's what the main section of the Clymer manual refers to. They didn't bother to clear things up in the section on 1980 and forward models.
     
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  9. grizld1

    grizld1 Grumpy old man Top Contributor

    A pass through the ultrasonic cleaner won't tell you what you need to know re. float function. Level the bike, slip some clear tubing on the drain valve under the float bowl, open the valve, set the petcock on "Prime," and observe fuel level in the tubing. If it rises higher than the float bowl flange, you have one of three problems: bad or dirty float valve, float level set too low, or float not floating (brass floats can develop holes).
     
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  10. ExSquid

    ExSquid XS650 Member

    The damn Feds and their "lean out the carbs so things have no power" philosophy. I had a heck of a time getting the plugs out of the A/F screws.
     
  11. ExSquid

    ExSquid XS650 Member

    I have the fibre floats.
     
  12. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

  13. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    Welcome exsquid - Green Bay is a long way from the ocean!

    I’ve read your thread and I wonder if all of your high voltage lead connections are solid (coil-to-plug wire and then plug wire-to-plug cap).

    I’m not sure what sort of coils and caps you have, but a lot of them have a screw-in type connector for the high voltage wire. Basically, if you look down into the connectors on the coil, you will see what looks like a small wood screw down in there. The spark plug cap will have the same thing down inside the plastic body. I tried to find a photo but couldn’t.

    Anyhow, you trim the spark plug lead to have a square end and then you trim back a 1/4” of the insulation and splay out the little conductor strands so that it looks like the photo below (image courtesy of forum member 5Twins, who has photos of everything).
    4B976E7E-3F8B-48B2-9A53-D3438571C6EB.jpeg
    Now, screw that bare wire end onto the wood screw while pushing it in. Secure the connection with the little rubber ferrule (see below and perhaps seal things with some dielectric grease) and then lock it down with plastic cap-nut - and Wah-Lah!
    ACE663F5-0017-4441-8596-7E61E52EA202.jpeg
    Before getting into the carbs, I’d check those high voltage connections.

    BTW - photos are very helpful when trying to advise folks.

    Pete
     
    Last edited: May 3, 2019
    Jim likes this.
  14. ExSquid

    ExSquid XS650 Member

    Pete,
    I bought the coil and XS Performance wires from Mike's. Its a green coil and it came with a plug in end for the wire. The plug cap is the screw in type. I haven't tried the .25" end cut and splay out the strands. I will do that when I get back from breakfast from the VFW.
    Thanks.
     
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  15. 5twins

    5twins XS650 Guru Top Contributor

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    It sounds like you still have the stock electronic ignition that came on the '80 and later models. DO NOT run it with one plug wire disconnected, you can damage the coil and/or ignition. If you want to disconnect one plug wire and kill one cylinder for tuning purposes, you must stick a plug in the wire and ground it to the engine. Don't just pull it and let it dangle.
     
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  16. XSLeo

    XSLeo XS650 Guru Top Contributor

    All dual output coil work the same. Stock or after market coil. When the coil sparks, the voltage flows out one plug wire to the plug, jumps the gap to the engine, across the engine to the other plug, jumps the gap, up the plug wire, back to coil.
    The green coils Mike's sells have a very high output. If you unplug one wire while the engine is running, the circuit is broken. The coil still tries to spark. With all that out put it has to go somewhere. Those green coils have weak insulation. This high voltage can leak through this insulation and cause shorts. This can destroy the coil. It can take just a few seconds for this to happen, or it could take longer.
    It's a good coil as long as you remember to insure it always fires through both plugs.
    I've run one for years without issues.
    There are many ways to kill a cylinder for carb balancing as the book talks about. On your carb holders there are vacuum ports. One is capped, the other has a hose to the petcock. Unplug the hose to the petcock. Plug with a cap. Now put the petcock on prime, ruin engine. To kill one cylinder uncap the vacuum port. This leans out the mix so it doesn't run. Adjust the other carb. Swap plugs, do other carb.
    On doing these adjustments you need to also slow the idle speed to just above stalling. The slower the idle speed the more effect so will notice as you adjust the mix screws. In leans the mix. Out richens the mix.
    Building adapters that fit between the plugs and plug caps is another method. Old spokes work well, The spoke nipples have the same thread as the spark plug end. Thread a nipple on the plug. Thread a spoke into the nipple. Cut the spoke long enough so that when you hook the cap on the spoke there is about a 1/2 inch between the cap and plug.
    Know using a jumper wire with alligator clips on each end hook one end the engine, let dangle, start engine, carefully clip the free end of jumper to the gap between the plug and cap. This lets the spark bypass the plug, killing that cylinder.
    Leo
     
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  17. MaxPete

    MaxPete Lucille, Betty & Demi - I suggest but THEY decide. XS650.com Supporter Top Contributor

    I like what spoke trick - cool!
     
  18. ExSquid

    ExSquid XS650 Member

    Well, its too late about the ground the plug lead and don't let it dangle. I let it dangle six or seven times. I received two K&L carb kits and I will do the full rebuild. The previous rebuild was done by a guy who only used a VERY basic kit. Cheap bastard. I did just pull the carbs off and tomorrow I will be stripping them down, cleaning and reassembling them according to the TECH instructions.
    I want to thank EVERYONE for their help and insight into my problems with my XS. I will continue updating my progress with the carb tuning. I also ordered an ignition kit from Mike's. it moves the trigger mechanism from the crankshaft to the camshaft. it was only $195.99.
     
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  19. 5twins

    5twins XS650 Guru Top Contributor

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    A crank firing ignition like the original electronic one is actually better than a cam fired one. The timing will eventually change on the cam fired type as the cam chain stretches.

    You seem to do things and buy things before asking about them. Had you asked, we would have steered you away from the MikesXS ignition. It's a blatant rip-off and imitation of the original Pamco ignition, which by the way, Mike's used to sell. I guess they were able to get it made up cheaper in China (although they didn't lower their asking price, lol). Carb kits usually aren't much good either. They contain all aftermarket stuff, not original Mikuni parts. Sometimes the quality is lacking and many times the included jets are the wrong size. An important o-ring in your carb set is the one on the mix screw and it's usually not included in the kits.
     
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