Airhead R100 horrible smoke at cold start

Discussion in 'Airheads' started by More_Miles, Nov 12, 2009.

  1. More_Miles

    More_Miles über-n00b

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    Inmates! Opinions solicited!

    Specs:
    1983 R100RT
    Stored overnight in the garage
    On centre stand
    Fuel valves off

    Symptom: Left (when astride the bike) cylinder burns clean at start up but smokes FURIOUSLY after about 1-2 seconds of running. Right cylinder burns (relatively) clean upon start up.

    If I was storing it over night on the side stand, I could buy the "oil lays in that cylinder" song. But I'm not, and it's sitting upright all night. It DOES clear, and if started up later on (i.e. warm start) no problem. This just started a few days ago. It also seems to be using a bit of oil. I know, it's a boxer, live with it...

    My thoughts, and feel free to tell me what an idiot I am for this line of reasoning:

    Over night, everything is cold, and a valve guide or valve stem contracts. This opens up a clearance into the cylinder. At start up, things are relatively dry and away it goes. Oil gets pumped into the top end (do boxers actually have "TOP" ends?) and out this opening into the combustion chamber. Smoke like hell... Warms up, things expand, seals back up and Bob's your uncle. Also, cold is in the -5 degree C range...

    Tonight when I get home, I'm going to pull the plugs to take a look. I also should get a compression tester sometime. I'm wondering if at 107000 km with an unknown engine I'm due for a top end rebuild. :eek1
    #1
  2. Pigford

    Pigford British

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    If you're lucky, it may only be the valve guide seals :wink:

    Or at worse, the guides!
    #2
  3. Solo Lobo

    Solo Lobo airhead or nothing

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    No valve guide seals on boxers....
    #3
  4. Mista Vern

    Mista Vern Knows all - tells some.

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    This sounds too simple, but in many cases where there is a mix of cool weather and humidity and the bike has not been ridden enough to get all the moisture out of the exhaust system, it will blow smoke-like vapor like a sumbich until all the moisture in the mufflers is gone.

    Odd thought, but could well be the case, especialy if this seems to be a brand new problem.
    #4
  5. bpeckm

    bpeckm Grin!

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    That's a thought!

    See if you can tell whether it is smoke, or steam. Though why one side would have more condensate than the other....

    If it is oil, my guess is that it continues to burn the same amount on the left side, but when it is hot, the oil is burned up more, leaving less to "see"....

    Your idea of pulling the plugs should give you additional clues/information..

    :D
    #5
  6. outfit

    outfit Been here awhile

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    You only put oil in upto the halfway mark between bottom & top mark's on dip stick? Otherwise it'll just burn off any oil above.

    Karl.
    #6
  7. sharkojoints

    sharkojoints is a bit slow sometimes..

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    Really? So I shouldn't have bothered just topping my oil up?
    #7
  8. Mista Vern

    Mista Vern Knows all - tells some.

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    Doesn't hurt anything, but it will prolly gravitate down to where it wants to be below the full mark. Airheads are funny that way.
    #8
  9. More_Miles

    More_Miles über-n00b

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    Gentlemen and ladies,

    Pictures to follow as soon as I can find my %!@#& cable for my camera... Card reader is still at work. Prior planning prevents piss poor performance I guess.

    Verbal (textual?) description:

    Left plug was somewhat brown, darker shade than lighter. I wouldn't consider it too bad but my prior experience has been with a 2 stroke that was running rich on the oil pump so I may be biased.

    Right plug was lighter, had a grey/white patch on the outside of the bend of the electrode. Personally I would think it's running too lean on that side, but again my previous experience is probably biasing me.

    So I set up the camera on the tripod, and started recording. Its always easier to SHOW what is happening than to describe it. The bike had sat for 22 hours from when I got home last night until just now when I tried to demo it. Of course, being a bike with "personality and character" it didn't do anything untoward....:huh

    Data point: It's been sitting in the unheated garage all day. Currently it's in the 10 degree C range, and considerably warmer than when it USUALLY manifests this behaviour. So, we're back to condensation... Possibly.

    Think I might just live with the "personality" and take my ribbing when I smog out the parking lot in the spring and fall... If I can catch it tomorrow morning I'll post the results.

    Just keep telling myself that personality and character is good in a bike. Otherwise it's a Tupperware clad two wheeled refrigerator...
    #9
  10. More_Miles

    More_Miles über-n00b

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    I should have mentioned that the oil level is just above the low marker on the dipstick and due for a change. It's getting that and a filter tomorrow. Almost time to put it up.:cry
    #10
  11. word1

    word1 I'm working on it...

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    Just thinking out loud here...

    You have a '83 which has the "new" style airbox, right?
    The breather might be different, but I'm wondering about the crankcase check valve and breather hose(s).

    The older style motors (with the round air filter) used a fiber washer and coil spring style check valve for the breather. These could get tired and allow excess crankcase vapor to be vented thru the breather hose(s) and into the airbox. This check valve was updated, at some point, to a reed valve which works much better.

    I also think the standard models used one breather hose which was routed into only one intake tube, while the S and RS models had a "T" and twin hoses - one into each intake tube.

    This might explain why only one side smokes.

    In any event, the check valve is located under the starter cover and is fairly easy to access.

    _jay
    #11
  12. Mista Vern

    Mista Vern Knows all - tells some.

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    That sounds fairly normal - slight discoloration could be anything from synching to plug gap, carbs, etc.

    I really think you need to take the bike for a longish (20 mile) ride and blow the snot out of it, put it on the center stand and see if the problem repeats. If it is as bad as you say the area should reek of oil; thus I am still betting on condensation. It takes a long time to get everything heated up enough to completly get the moisture out of the muflers (actually, you can't ever get them totally dry, but you get the idea).
    #12
  13. Solo Lobo

    Solo Lobo airhead or nothing

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    So it looks like no one asked...

    What color is your smoke?

    Also, FWIW, the stock BMW vavle guides on the early 80's bikes are soft garbage... my exhaust guides were totally played out at 20,000 miles!
    #13
  14. Solo Lobo

    Solo Lobo airhead or nothing

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    My '81 G/S has twin hoses...
    #14
  15. More_Miles

    More_Miles über-n00b

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    Yes, the new style air box. I'm going to dig in and look at it shortly.

    Well, I ran the snot out of it yesterday (4 hours plus, all at 110 km/h and higher) then let it sit while had dinner with friends. About 5 hours that. Heavy frost on the bike, cranked it up and drove everyone inside...:lol3 But when warmish, no problems. More on smell and colour momentarily...

    Smoke is whiteish grey. The more I think of it, it doesn't LOOK or SMELL all that much like burning oil. So I'm leaning to condensation. One of the reasons I am worrying about this is that I know that the guides are shite on this era engine, and it's a mystery to me maintenance wise. But why does it always come from the left cylinder? Enricher maladjustment? Worn or clogged jets?

    I dropped the bowl's on the carbs tonight just to see if there was anything settled in there. There wasn't actually. I'm really leaning more towards "it's the way the bike acts when it has better sense than the rider does about cold" kind of answer.
    #15
  16. WooHoo

    WooHoo Adventurer

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    I have the same symptoms (assuming it's oil and not water burning) with my 89 R100GS (and previously on /5's.).

    I am pretty sure in my case it's caused by the way I park my bikes....

    When I get home I ride down my drive and shut off the engine and gas and prop the bike on the side stand while I open the garage, then I push the bike in and haul it up on the centre-stand where it sits till next time.

    About one time in two she'll smoke on startup from the left.

    I always thought the chance occurrence was a result of:

    1. The oil level.
    2. where in the stroke the piston ended up sitting ( maybe more TDC = more oil to dribble down :dunno); and
    3. where the ring gaps happened to be at that time.

    You may have a totally different issue but while I noted you said you leave it on the centrestand overnight, you did not say you didn't use the side stand as part of the parking process. If you do, this may be your issue as well.

    I agree it can be real embarrassing when you billow smoke like the Queen Mary, especially when parked bum to curb in front of your favourite cafe with the nice alfresco dining....

    I've heard it recommended leaning the bike to the right for a few seconds after shutting down the engine prior to parking to avoid this. I tried it but didn't really help me much.

    Ta.

    Tim
    #16
  17. Rob Farmer

    Rob Farmer Long timer

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    I had exactly the same thing on my 100/7. It stood for several years at one point in it's life and had some corrosion on the bore that would allow a small amount of oil to sit in when the bike stood overnight. Firing it up resulted in a cloud of smoke that lasted anywhere from 30 seconds to a minute, once cleared the bike would be fine all day. I honed the bore out a couple of years ago, re ringed it and it's never happened again.

    <QTLEND></QTLEND>unfortunately you have nikasil bores so you may not be able to hone them.<QTLBAR id=qtlbar dir=ltr style="PADDING-RIGHT: 0pt; DISPLAY: inline; PADDING-LEFT: 0pt; Z-INDEX: 999; LEFT: 272px; PADDING-BOTTOM: 0pt; CURSOR: pointer; LINE-HEIGHT: 100%; PADDING-TOP: 0pt; TOP: 138px; BACKGROUND-COLOR: rgb(236,236,236); TEXT-ALIGN: left; opacity: 0.9; -moz-border-radius-topleft: 3px; -moz-border-radius-topright: 3px; -moz-border-radius-bottomright: 3px; -moz-border-radius-bottomleft: 3px"></QTLBAR>
    #17
  18. More_Miles

    More_Miles über-n00b

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    Inmates,

    A day late and a dollar short but here we are.

    These are the plugs. Left is left and right is right. I'm going to pop a new set in tonight.

    <table style="width: auto;"><tbody><tr><td>[​IMG]</td></tr><tr><td style="font-family: arial,sans-serif; font-size: 11px; text-align: right;">From Motorcycle Bits</td></tr></tbody></table>An oil check prior to starting up. Yes, it's low, getting changed tonight with a new filter.

    <table style="width: auto;"><tbody><tr><td>[​IMG]</td></tr><tr><td style="font-family: arial,sans-serif; font-size: 11px; text-align: right;">From Motorcycle Bits</td></tr></tbody></table>It was about -1 degree C this morning when I headed to work. Here's the proof!

    <table style="width: auto;"><tbody><tr><td>[​IMG]</td></tr><tr><td style="font-family: arial,sans-serif; font-size: 11px; text-align: right;">From Motorcycle Bits</td></tr></tbody></table>Now, before anybody makes comments about my riding gear, it's the best I could come up with at this time. Here's the video of the cold start, after sitting over night in the garage. Also, please excuse the mess, if you are coming to see me, come any time, to see the house or garage, make an appointment!
    <object height="505" width="640"></object>
    Questions have been asked about my parking style. Sometimes I shut down on the side stand for a couple moments while I open the garage. Sometimes I let it idle on the side stand while I do the same. I always run it into the garage under power since there is about a 1 foot rise and a 3 inch lip at the door. Okay, so I'm lazy...

    Now that you can see the symptoms, thoughts? After smelling the exhaust, it's doesn't smell like rich, vapour laden exhaust. It also doesn't really smell all that much like oil burning...<object height="344" width="425">
    <embed src="http://www.youtube.com/v/yoft3SChKsI&hl=en_US&fs=1&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="344" width="425"></object>
    #18
  19. sharkojoints

    sharkojoints is a bit slow sometimes..

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    Does that smoke still happen if you don't use the choke?
    #19
  20. bpeckm

    bpeckm Grin!

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    Sure looks like oily smoke to me..... and the left plug has deposits which would be consistent with oil burning.

    Do a compression check.

    You might also want to do a simple check at the "output" of the crankcase relief: there is a tube that dumps into the right air tube: pull the airtube off the right carb/rightairboxiside, and stick your thumb over it while the bike idles. If you have a lot of really oily air there, it could be the problem... the oily airmix is being sucked into the carb(s). Pull the airtube off the left side: is it oily over there?

    I am thinking that if the onset was sudden, you may have a broken ring. It could also be valve guides, but I don't think that you would be burning that much oil with a bad valve guide.....

    :scratch

    Both sides are smoking, though it appears that the smoke is thicker at first from the left.. if you block the left exhaust with a rag, does the right side sound the same.... I am wondering if most of the smoke is pushed over to the left side because the right exhaust is sorta plugged with oily-ness....
    #20