Odd airhead problem

Discussion in 'Airheads' started by England-Kev, Dec 13, 2011.

  1. England-Kev

    England-Kev Long timer

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    I am having an odd problem with my R80ST...

    If I don't ride it for a while, it will not start, it just turns over and over, and won't fire up? it never used to do this. even when stood during winter months, you could turn on the fuel, full choke, ignition on, and it would fire right up.

    But now I can go through that same sequence, and it will just turn over, I even gave it extra power by jumping it from my works van, but it still just turned over for ages, finaly it fired up, and then ran great, and would then start instantly.

    Now I think this could be a fuel starvation thing, I wonder if the new high ethanol fuel is gumming up the jets when parked up. I say this, as I pulled a plug on Saturday, and it was dry not wet.

    Your thoughts please.:huh
    #1
  2. supershaft

    supershaft because I can

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    See if the plugs are sparking next time.

    Make sure your choke cables are adjusted correctly.
    #2
  3. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Check the choke cables, but also the choke jets in the float bowls that they're not obstructed, plus the choke bodies tend to loosen and the gasket pulls in allowing a vacuum leak which equates to no suck - no choke action.
    #3
  4. mark1305

    mark1305 Old Enough To Know Better

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    Kevin, I'm with your guess about gas gumming up the carbs. The blend here in FL has gotten so bad that gas powered yard tools try to gum up if not started on a weekly basis. We are nominally at 10% ehtanol here, but the other seasonal additives appear to be carb unfriendly as well. Don't know how your gas blends over there compare, but could be the culprit.

    And to echo what wirespokes said - my ST was acting similarly a couple of year ago prior to the partial carb overhaul. Sure enough, the choke pickup tube had the little tiny jet in the corner of the float bowls clogged up.
    #4
  5. DoktorT

    DoktorT BigBrowedNeandereer

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    Do verify the battery. Low volts during cranking can mean not enough amps left for a sharp spark.

    A pritz of starting fluid is a quick test. If no jump to attention from that, you know it's a spark issue. If it does fire, fuel or vacuum issue. Once running, any vacuum leak can be found with the starting fluid.

    Just investigate the usuals mentioned above. You can have the culprit in hand in 10 minutes. Don't be surprized if you find more than one weakness adding up to no cold start, so do inspect and test all possibles noted.
    #5
  6. CurlyMike

    CurlyMike Formerly SaddleSoar

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    I would also check valve clearance and timing.
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  7. Westbrook

    Westbrook Been here awhile

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    Can you elaborate on the method for finding vacuum leaks with starting fluid?
    #7
  8. Cogswell

    Cogswell Spudly Adventurer

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    Do you run the float bowls dry prior to parking the bike, or leave them full of petrol and just turn off the tap ?
    I have found if I run the bowls dry before parking it is a lot easier to start with "fresh from the tank" fuel in the carbs.

    My $.02


    Mike
    #8
  9. goatroper

    goatroper Been here awhile

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    And for the bonus points.............. You've been hangin' around that plunger-framed trollop.

    How did I do?
    #9
  10. Wolfgang55

    Wolfgang55 Long timer

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    Have done a bit of carb work & not trying to get in anyone's space here.

    What I've seen is the NON ethynol gas would gum or sticky up a carb if allowed to stand in a carb for long periods of time w/o a stablizing additives.
    That said, what I have found in the same carb on a different bike that ran on our 10% ethynol & when left sitting w/o any fuel additive was Fuzz & water in the bottom of the carb bowl. The main intake jet, the pilot jet, needle jet & more were near green w/ fuzz. I think you get the picture here. The brass was actually fuzzed over not gummed up.
    Ok, we may at first think a non working carb is all the same but actually it's not.

    If you clean & de fuzz the carb you still have the same separation taking place in the botton of your fuel tank.
    What I have seen is when the bike is running it will injest a bit of moisture & still run, not perfect but it will run. The moisture will again begin to settle at the bottom of your carb. Our bikes' tanks are always moving left & right etc, so the better fuel is still flowing in to the carb in higher levels over the water.

    Let this bike sit around again & in a shorter time than before the same bike using the same tank of fuel will now be on a fast track to fuzz up again.

    I'm not trying to sell any product here because I've not found all fuel additives do all thing for all fuels.
    So when thinking about going to a fuel additive, read the lable & be satified you are buying what will help your current fuel to not seperate, as time go on.
    #10
  11. DoktorT

    DoktorT BigBrowedNeandereer

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    Works best with a digital tach to find small vacuum leaks. Bigger leaks can be heard by ear.

    Set the engine running at idle. Shoot a little spritz of starter fluid at the various clamps and interfaces, carb to head, enricher gaskets, and watch the tach or listen for increase in rpm. Just a quick and easy way to eliminate one of the usual suspects.
    #11
  12. Westbrook

    Westbrook Been here awhile

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    Thank you!
    #12
  13. Horsehockey

    Horsehockey A GPS? Huh?

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    Do not ignore this suggestion. Particularly valve clearances.
    #13
  14. supershaft

    supershaft because I can

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    I shut off /2 petcocks because you have to. It pays to shut them off a bit before the ride is over. /5 on wise on the other hand, properly set up Bings and Dellortos don't leak. I almost never shut my airhead petcocks off because it doesn't matter. If I am gone for a long time or my bike is getting transported, sure but other than that . . . no.
    #14
  15. England-Kev

    England-Kev Long timer

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    I always run the float bowls dry, valve clearences are good, and I have never had to adjust the timing in the 3 years I have owned it.

    I will check the choke tubes this weekend, could this problem be sticking weights in the bean can?
    #15
  16. supershaft

    supershaft because I can

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    I remember when the sticking weights bulletin first came out and I have had my eyes open for it every since. In all the airheads I have worked on I have never found them sticking in a bean can. I have since heard so many people on the net talking about it. I have still never seen it except for maybe once but I fixed too many things at once to know for sure. I have seen a couple completely F'ed up for water crossings but I don't count them. I have fixed tons of fast idling or other engine troubles always blamed on sticking bean can weights but it has always been something else. Namely carb adjustments. I have seen regular points advances cause more trouble in my experience but not by much. I think part of the problem is a couple of guru's "definitive" sticking weights diagnosis methods that are in fact not definitive at all. For these reasons I think it is highly unlikely.
    #16
  17. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I'll agree with that. If it runs fine once started, the problem isn't the advance!

    The most likely areas to check are the choke and coil/plug leads/connections to the coil. But the plugs not being damp really points at the enricheners.

    If the throttle is opened at all when cranking, the vacuum needed by the chokes will be drained off. So leave the throttle closed until the engine actually starts.
    #17
  18. Mike Ryder

    Mike Ryder Kriegerkuh

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    Be carful with starting fluid [ether] as it is FREAKIN flamable. A small spark is all it takes to light up. I know fires are fun but.....
    If you can, use unlit propane in the same manner.
    #18
  19. disston

    disston ShadeTreeExpert

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    I don't think anybody answered you yet? Now that you have been warned that using starting fluid, especially in the method I'm going to describe is dangerous, we can proceed. This method belongs properly in the large category "Shade Tree Mechanics". A forum that doesn't even exist but which I am a leading member of, go figure.

    Spray starting fluid around the air tubes and intakes of a running engine. If the idle noticeably changes, usually up, then you have found an air leak. This can be done with other sprays like WD-40 or carb cleaner but like implied they may not cause idle to go up. Starter fluid will make the idle go up.

    Charlie
    PS; I think England Kev has the neatest bikes.
    #19
  20. CurlyMike

    CurlyMike Formerly SaddleSoar

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    England-Kev, what was the final diagnosis that fixed the problem...
    #20