1. Dismiss Notice
  2. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice

Bike wont start, need expertise

Discussion in 'The Garage' started by jmart94, Feb 8, 2014.

  1. jmart94

    jmart94 XS650 Member

    When i bought the bike, the seller cranked it up (took a good 7-8 kicks) but it eventually started, then the next day i got it running (yet again a good 10-12 kicks that time). And ever since then i have not been able to get her started. I have tried to kick start that thing until my legs have turned to jelly. I took the carbs off today to see how clean they were, and checked the petcock. They all seem very clean to me (this is my first bike so i hardly know what to look for). But i wanted to post some pictures and see what other people have to say. I took the spark plugs out and took pictures of those as well...

    from my understanding, you need gas/air mixture, compression, and a spark at the right time for the engine to start...if the carbs are clean and are get getting the fuel, then maybe im not getting enough air and need to adjust? Im not sure, i took pictures so if anything seems off please let me know.

    im completely new to mechanics so id appreciate some help...

    Attached Files:

  2. jmart94

    jmart94 XS650 Member

    forgot to mention that i checked the battery and it read a 17.7 with the key turned
  3. azman857

    azman857 '80 XS 650SG Rider Top Contributor

    Help us help you. What year is your bike? What ignition are you running? 17.7 volts from a 12 volt battery? Stock or custom wiring? What sparkplugs are you running? Coil?
  4. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Your problem is obvious. The solution not so much. The idle mixture screws have never been touched. The brass plugs "prove" that. I will guess you are the second person to "clean" the carbs without knowing anything. Drilling out the brass plug and removing the idle mixture screws, R&R of all circuits and jets and at the very least, replacing the o-rings on the float valve bodies is needed. Whether you take this on or find someone to do it for you that is the needed preliminary to the vroom vroom noise you want to hear. Find the tech button, search out the carb guide. Good luck and please report on how this goes both good and bad.
    There is a sort of fable out in the wild that you can take a 30 year old set of carbs, dip them in some chemical bath till they "look shiny" and you are done. This is pure wishful thinking, carb cleaning is hard fussy work that requires patience and fastidious attention to detail. Oh you also have to avoid f#$%ing things up with poor tools and technique. Sorry but it is MUCH easier to make things worse than better....

    I am not trying to discourage you, plenty of guys have worked this out with good results even if they ended up replacing some parts as they learned the tricks.

    Addition: the tiny little orifice that feeds the idle enricher circuit in the bottom of the float bowls is probably blocked too.

    Oh it appears you are working on a set of 1981 XS650 special carbs?
  5. 5twins

    5twins XS650 Guru Top Contributor

    Yes, the choke jet is most likely plugged. When that happens, the choke ceases to function and the bike will be very hard to start cold, sometimes impossible. I notice some crud in your float bowl bottom (your pic #3). The intake for the choke jet is that hole on the lower left. When you turn the choke on, fuel is sucked into that hole to feed the choke. So is any crud in the bowl. That plugs the jet quite nicely. Here's how to check if yours are clear .....


    As Gary mentioned, you must uncap and remove the mix screw in order to do a proper cleaning of the idle circuit.
  6. jmart94

    jmart94 XS650 Member

    gggGary i dont pretend to know anything, and i didnt clean the carbs, i simply took them off the bike to look at them and compare them with what i see in the manual...i just bought this bike so i am just getting a feel for what condition it may be in, or what the previous owner has done. Im very thankful for this community of others who are not only knowledgeable but also willing to help out people naive to the craft as i am...so thanks for the info...

    that being said, i am very much willing to take this on...im just fresh out the gates, so it may take me a while plus a lot of noobie questions answers from all you experienced veterans out there.

    and it is indeed an 81 special,

    the spark plugs are NGK BP7E S, i live in south louisiana if that makes any difference in the hot or cold plugs.

    ill check on what yall have mentioned, this sponge of a brain will eventually soak up what yall are putting out

    thanks again for the input guys, ill post results later on
  7. XSLeo

    XSLeo XS650 Guru Top Contributor

  8. jmart94

    jmart94 XS650 Member

    also here are some other pictures if yall want to look and see if you just see any red flags, things that arent right or anything, thanks

    also, the multimeter i bought from harbor freight is not supposed to test batteries exceeding 9V...so thats why i guess it read 17.7, my mistake

    Attached Files:

  9. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Pics are great. Not try'n to bust your chops just kind of a heads up and hopefully an understanding that there are no shortcuts to good running carbs. I think you should pitch those cheesy pod filters. Do a search on here on uni filters. Those pods "might" be your biggest problem. But read the guide, follow the tips given so far. I will guess the harbor freight multi meter will check the voltage fine, don't use the "battery test" position, select DC volts probably select the 20 or 30 (next voltage OVER 12 volts) range. That should show your battery voltage and then when the bike is running help check test the charging system. The replaced fuse box is a good thing, those fuses will be fine if the connections were well made, (crimps or solder) Your plugs are correct your "outside temp" has nothing to do with plug "heat range" but that's another tech article.
    Are all the cells in that battery full of water? the cell on the right looks wrong (dry) but it could be just the lighting....
  10. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    More hints

    DO NOT crank the engine with the ignition on unless the spark plugs on the wires and grounded to the engine. It's possible to fry the electronic ignition. That plug looks wet is that oil or gas? Are both plugs wet?
  11. jmart94

    jmart94 XS650 Member

    XSLeo thanks for the carb guide, lots of good info to dive into

    gggGary i appreciate the heads up on the multimeter, that thing looked like gibberish to me, and yes those pod filters are pretty cheesy, ill look up those uni filters. Ill need to check that battery level when i get home, they all looked full except that one spot on the right you mentioned, it did seem dry.

    Only that one plug was wet, and ill need to inspect it when i get home to see if it is oil or gas
  12. XSLeo

    XSLeo XS650 Guru Top Contributor

    On the meter, I might suggest you google "How to use a multimeter"
    They are not hard to use once you understand what they can do.
  13. jmart94

    jmart94 XS650 Member

    Well i took my time and studied the hell out of that carb guide before breaking them down. Then i built up the courage to take them apart and clean them, removing the brass plug to get to the idle mixture screws felt like i was performing surgery considering i didnt know how far down that screw was from the plug, but i successfully got them out without any damage. I replaced all o-rings and the gaskets, and enriched the mixture by turning those idle mixture screws to 2.5 turns out from tight. Upgraded to foam unifilters. Gas tank had lots of small rust particles and maple syrup for gasoline, i drained it all (it was disgusting), my pilot jet on one of the carbs was clogged with little rust particles. Then i used the KBS rust seal method, came out looking great! Then i figured while i had the tank off id go ahead and strip that cheesy speed racer paint job the PO put on it, it was a cheap varnish anyway, spilled gas would cloud it. Ordered some yamaha emblems and put those on. All that being said, i put her together sunday and she fired up on the second kick! It was a good feeling. This is the first thing ive ever tried to fix, felt gratifying to learn something new and actually see the fruits of my labor...thanks for all the responses to my naive questions. Here are some pics of it all after all the work, im not too fond of the seat, thats the next project...also i need to set up the signal lights and the horn isnt working...and i need to replace chain and sprockets!!! man i have a lot of work to do.

    Attached Files:

  14. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
    :thumbsup: on your success.
    gggGary likes this.
  15. Yep, congrats! Good to hear!

    On starting the bike...I guess we all have our way.
    I put the choke on, open my manual petcock, cycle the engine with the kicker once or twice and then turn the key on and kick it again. Fires every time.
  16. 5twins

    5twins XS650 Guru Top Contributor

    Yes, you did good, lol. See, carbs aren't that mysterious. If you refer back to the carb guide, I think you'll find the BS34 mix screws like 3 to 3.5 turns out better.

Share This Page