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Hard to Start Hot Engine XS650SH

Discussion in 'The Garage' started by Paul Sutton, Dec 19, 2017.

  1. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    I wonder if some one can point me in the right direction. My SH starts easily from cold using the choke on the 1st stop (BS34) and throttle fully closed, even at 0 Celsius. Usually only takes 2 or 3 kicks maximum. The bike pulls well through all gears without any missing or splutter and no backfire when going down hill with throttle closed.

    When the engine is heated up after riding for say 30 minutes or more I find it reluctant to start either by kicking or using the electric starter unless I open the throttle slightly. I have checked the plugs and they look good without being too rich or lean - light grey in colour.

    Once the engine is restarted it then runs without fault. The issue is restarting when engine is hot.

    Thank you for any thoughts you share.
     
    Jim likes this.
  2. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    Paul,
    are you saying here that it starts easily with the throttle cracked a bit? Or is it still hard but not as bad?
     
    Paul Sutton likes this.
  3. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Jim, I only need to open the throttle very slightly to restart when hot and the restart is very easy i.e. 1st kick. I have spotted a comment by DogBunny in the following 2016 thread where in Entry 7 he says this is normal:

    http://www.xs650.com/threads/81-han...-hot-need-a-plan-of-attack.45769/#post-458001

    It may be that this is more noticeable in Winter because it was not happening back in Spring and Summer??
     
    Jim likes this.
  4. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    I'm being a bit cheeky here... but we've had electronic fuel and ignition systems for so long now that I think people forget what it was like in the "old days" of carbs...
    We've grown used to just turning a key or pushing a button and letting the computer sort it all out.
    My opinion Paul, if that's your only complaint... you're a lucky man:)
     
    Last edited: Dec 19, 2017
  5. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    Thanks for Jim, I have been out of riding for 30 odd years but I do not recall this issue before. I will just go with your's and DogBunny's comments.

    I am a lucky man!!!
     
    Jim likes this.
  6. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    I'd bet even money that 30 odd yrs. ago, cracking the throttle was a subconscious task that you took for granted;)
     
    Paul Sutton and Mailman like this.
  7. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, on hot starts, cracking the throttle open a hair is normal, at least on my '78. Cold starts with choke are no throttle until the motor catches, then I feed little blips into it to keep it going and bring the R.P.M.s up, sort of nurse it into running, lol.
     
    Paul Sutton and Jim like this.
  8. Mailman

    Mailman Hardly a Guru Top Contributor

    That sounds exactly like my start up routine.
     
    Paul Sutton and Jim like this.
  9. Paul Sutton

    Paul Sutton Buckhorn Gang Member Top Contributor

    I am thinking hard but do not recall doing this on my 1B all those years ago. Thanks for the conformations on this being normal. I shall sleep peacefully tonight once I have watched Gene Hackman in Heist.
     
    Jim likes this.
  10. littlebill31

    littlebill31 Smells of Raw Fuel

    My stock '81 did this. Every time after it was warm, I had to crack the throttle just a hair.
     
    Paul Sutton and Jim like this.
  11. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

    Yup - me too. I think that Jim’s comment is right on.

    Today’s vehicles have closed loop digital engine management and fuel injection systems that measure a bunch of parameters and then adjust everything from mixture to spark timing to throttle position literally hundreds or thousands of times per engine cycle. That looks after a multitude of sins ranging from cold crappy weather to bad fuel to changes in altitude to engine wear including poor compression and dirty spark plugs - and it has spoiled us.

    I give a lot of public talks about automotive technology and I often ask a crowd “please raise your hand if your car has failed to start this week...this month...this year...in the last 5 years?

    It is a very rare thing for anyone’s hand to go up - and then I ask the older folks to cast their minds back to the 1960-70s timeframe. Every (grey haired) head in the room nods knowingly. Our bikes have that same 1970s open loop, primitive technology carburation and ignition systems (for the most part) and that is why they run as they do.

    Pete
     
    Paul Sutton and Jim like this.
  12. azman857

    azman857 '80 XS 650SG Rider Top Contributor

    Indeed! The last bike I had that had points in it was the Norton 850. I didn't have it long enough to get some sort of ignition upgrade. Amal weren't exactly high tech carbs . I noticed late '79-'80 most mid to large cycles got the E-Ignition.
     
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  13. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

    My 2007 ST1300 has 73000 km (around 44,000 miles) on it and it’s a decade old. It runs EXACTLY the same every single time I start it. My XS650 runs a little different from one day to the next.
     
    Paul Sutton and Jim like this.
  14. azman857

    azman857 '80 XS 650SG Rider Top Contributor

    Shoot. Sometimes "The SG" runs different from one ride to the next, the same day!
     
    Paul Sutton and Jim like this.
  15. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    I'm guessin' then that you never had the joy of re-shiming the Iso....whatever it's called engine mount rubbers. What fun that was....:banghead:
     
    Paul Sutton and gggGary like this.
  16. azman857

    azman857 '80 XS 650SG Rider Top Contributor

    No, I reshimmed it a time or two. It's just part of owning one.
     
    Last edited: Dec 20, 2017
    gggGary and Jim like this.
  17. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Every one of my OLD bikes has its own starting procedure and cold starting is different than warmed up starting. I really don't notice the differences, they're automatic.

    I know you're kick starting, but dirty, worn starters work better cold than warm/hot.

    Scott
     
    Paul Sutton and Jim like this.
  18. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    If you're looking for work suspect slightly weepy float valves or leaking float valve o-rings. eith will put a bit of a flood in it. But vacuum petcocks keep it from getting out of hand. Anyone remember the mistake of touching the throttle on a 60's V8 on a start 15 to 30 minutes after it last ran? The carb had cooled enough that opening the throttle set the choke. You'd have to go out and stick something in the choke plate to wedge it open to clear the flood. A big flame thrower wasn't uncommon. The guy under the hood would be yelling "KEEP CRANKING!" to suck the flame in.
     
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  19. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    Remember starting on a cold day and running back in the house? Two minutes later the engine would be screamin' away at 3 grand till you jumped in and tapped the gas pedal.
    How far we've come...
     
    Paul Sutton, MaxPete and gggGary like this.
  20. xjwmx

    xjwmx XS650 Guru Top Contributor

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    A car that would stop when you turned the key off was good progress.
     
    timbeck likes this.

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