Coo, that's running rough

Discussion in 'Classic Motorcycles' started by The Older Gentleman, Aug 30, 2005.

  1. Did the tappets, timing and a carb balance on the 400 Four on Monday.

    God, it makes a difference, especially (I know this sounds silly) with
    brand new throttle cables. Smoother, sweeter, more controllable.

    Erm, until coming back from work today when it started running like
    shite. Lumpy, engne racing, loads of clutch chunter, generally horrible.

    Hm. Sounds carb-y to me. Off with the tank and let's have another look
    at the balancing. Something must have loosened off.

    Memo to self - ensure all locknuts on the carb adjusters are properly
    tightened......
     
    The Older Gentleman, Aug 30, 2005
    #1
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  2. /me goes looking for errant locknuts on the DT's carb.

    --
    Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
    Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
    GSX600F, RG250WD, DT175MX "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
    WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
    KotPT -- "for stupidity above and beyond the call of duty".
     
    Dr Ivan D. Reid, Aug 30, 2005
    #2
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  3. The Older Gentleman

    Pip Luscher Guest

    Still idling fast?
     
    Pip Luscher, Aug 30, 2005
    #3
  4. What's the problem here? Because it rode fine when I, my neighbour, best
    mate, and then Timo rode it.

    Ah.

    Timo.

    All becomes clear.
     
    The Older Gentleman, Aug 30, 2005
    #4
  5. The Older Gentleman

    Salad Dodger Guest

    What's the problem here? Because it rode fine when I, my neighbour, best
    mate, and then Timo rode it.[/QUOTE]

    Ivan's spent more time arseing about with the DT than I did
    overhauling the Wing.

    I think he's decided that because he's got a teenager's bike, he's got
    to take everything apart to see how it works.

    With predictable results.
    --
    | ___ Salad Dodger
    |/ \
    _/_____\_ GL1500SE-V/CBR1100XX-X/CBX1000Z
    |_\_____/_| ..78868.../...19540.../..30836.
    (>|_|_|<) TPPFATUICG#7 DIAABTCOD#9 YTC#4
    |__|_|__| BOTAFOT #70 BOTAFOF #09 two#11
    \ |^| / IbW#0 & KotIbW# BotTOS#6 GP#4
    \|^|/ ANORAK#17 IbB#4 PM#5 WG*
    '^' RBR Clues: 29 Pts: 485 Miles: 1967
     
    Salad Dodger, Aug 30, 2005
    #5
  6. The Older Gentleman

    Lozzo Guest

    Champ says...
    He could tell you the square root of a packet of crisps, but not how to
    open them.
     
    Lozzo, Aug 31, 2005
    #6
  7. 'T'won't idle properly. Nor start. Then when it's going and
    hot it idles at 4,000+ rpm for a minute or two before dropping back to
    1500 rpm. The idle screw is in far too far -- it was bottomed out
    originally.

    After a short motorway burst (Maidenhead-Langley) during which it
    ran onto reserve, it cut out at the first lights. Took me a while to
    get around to pushing it -- it started immediately but wouldn't idle.
    I've had the carb off and cleaned a couple of times, everything is
    infuriatingly nominal. New plug, of course.

    I discovered that the air-filter had been replaced with a bit of
    knitted cloth (the type we used to pack smoked hams in), well oiled.
    Neither removing that nor buying the proper foam element has made any
    difference.

    I'm at the point of checking the oil pump (when I get a spare weekend)
    and then looking even more carefully for leaks in the intake manifold.
    At some point I should check the exhaust, tho' it seems to be free enough.
    After that? Crank seals, I guess...

    --
    Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
    Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
    GSX600F, RG250WD, DT175MX "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
    WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
    KotPT -- "for stupidity above and beyond the call of duty".
     
    Dr Ivan D. Reid, Aug 31, 2005
    #7
  8. You peeps really know how to kick a guy when he's ...asleep!

    And Loz, I'll let you into a secret about crisps. In Adelaide
    they like their crisps broken up into ickle bits, so they kill two birds
    with one stone, opening the packet by bringing a clenched fist down
    sharply onto the new packet. <POP!>

    --
    Ivan Reid, Electronic & Computer Engineering, ___ CMS Collaboration,
    Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
    GSX600F, RG250WD, DT175MX "You Porsche. Me pass!" DoD #484 JKLO# 003, 005
    WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
    KotPT -- "for stupidity above and beyond the call of duty".
     
    Dr Ivan D. Reid, Aug 31, 2005
    #8
  9. Ivan's spent more time arseing about with the DT than I did
    overhauling the Wing.

    I think he's decided that because he's got a teenager's bike, he's got
    to take everything apart to see how it works.

    With predictable results.[/QUOTE]

    Ah, right, I see. No offence to Ivan, but I've never met anybody with
    such an immense brain, who devoted so little of it to understanding of
    things mechanical.... ;-))
     
    The Older Gentleman, Aug 31, 2005
    #9
  10. Bizarre, because it did both perfectly when I had it.
    That indicates running too lean to me. Have you done a plug chop?
    It's not going to be the oil pump. Crank seals are possible but unlikely
    - the sure-fire way to tell is if it smokes excessively and the gearbox
    oil level drops, because that indicates shot seals as the gearbox oil
    gets into the combustion chamber. A smell of petrol in the gearbox oil
    is a ditto.
     
    The Older Gentleman, Aug 31, 2005
    #10
  11. The Older Gentleman

    Guest Guest

    I still wonder if the exhaust is a bit clogged. Try a de-coke (caustic
    and a potato (stand it upright in a bucket).

    No doubt it can be done with YAG lasers too, Bond-style, but personally
    I favour the King Edward for bung-ability. You don't have to weld the
    two halves back together afterwards either.

    Regards,

    Simonm.

    PS: If the timing was a bit advanced it would run OK-ish, but not tickover, and
    it could well overheat. Your description sounds like it's overheating, and/or
    lean. Does the plug looks rather unhappy after a run? You may yet have an inlet
    air leak.
     
    Guest, Aug 31, 2005
    #11
  12. The Older Gentleman

    TOG Guest

     
    TOG, Aug 31, 2005
    #12
  13. The Older Gentleman

    Guest Guest

    "TOG@Toil "
     
    Guest, Aug 31, 2005
    #13
  14. The Older Gentleman

    Andy Clews Guest

    Thus spake Dr Ivan D. Reid unto the assembled multitudes:
    Ah, those Awstralians have no finesse.

    My favourite trick with crisps is to grip the unopened bag firmly with both
    hands, and squeeze hard so that the top pops open with a nice loud bang.
    With practice and skill, the bag can be opened in this way without crushing
    the contents. I once nearly killed our elderly pub landlady doing this; she
    thought somebody had been shot and nearly keeled over from the shock. Care
    needs to be taken to ensure the *top* of the bag is the bit that opens, not
    the bottom, which can of course lead to lapfuls-of-crisps misery. It's
    also a good test for an airtight bag; any leaks are immediately apparent
    and the bag with possibly contaminated or stale contents can be given back
    to the landlord for substitution or refund (or a '**** Off' if the landlord
    isn't very friendly).
     
    Andy Clews, Aug 31, 2005
    #14
  15. The Older Gentleman

    Paul - xxx Guest

    Dr Ivan D. Reid came up with the following;:
    Couldn't be as simple as the throttle cable either being not long enough, or
    too long, and coming out of it's ferrule/holder on the carb top/twistgrip
    and when it's opened, not returning fully, could it?

    Or the carb throttle slide getting stuck up the bore when it's got a bit
    warm, maybe having been ovalised/deformed slightly by someone dropping it
    whilst changing the throttle cable?

    Or, indeed, the mixture and tickover screws set totally, absolutely,
    completely wrongly?

    Might be worth, and I don't mean to be disparaging here, taking it to
    someone who is good with two strokes to have a lookie-see. ;)
     
    Paul - xxx, Aug 31, 2005
    #15
  16. The Older Gentleman

    TOG Guest

    Or even putting the slide in the wrong way round - something possible
    on more than one bike I've owned.....
     
    TOG, Aug 31, 2005
    #16
  17. The Older Gentleman

    Paul - xxx Guest

    came up with the following;:
    I dunno about that on a Mikuni ISTR they mostly have a quide groove down
    them with a pin/dowel in the carb body to stop that ... though if it's
    broken .... ;)
     
    Paul - xxx, Aug 31, 2005
    #17
  18. The Older Gentleman

    Lozzo Guest

    The Older Gentleman says...
    There's only oil on one side of the crank. If it's leaking air from the
    alternator side it won't affect the oil level. It's more likely to be
    the alternator side too, as this is the one that dries up because
    there's no oil there.
     
    Lozzo, Aug 31, 2005
    #18
  19. The Older Gentleman

    Lozzo Guest

    TOG@Toil says...
    Left crank seal.
     
    Lozzo, Aug 31, 2005
    #19
  20. Yes, good point.
    Hmmmm.... how does one detect a shot crank seal on the alternator side?
    Two-stroke mix around the alternator, I suppose.
     
    The Older Gentleman, Aug 31, 2005
    #20
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