Weird Sputtering/Grinding at 80+mph -'00 1150GS

Discussion in 'GS Boxers' started by jdgmntDay, Oct 6, 2012.

  1. jdgmntDay

    jdgmntDay Adventurer

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    The longer I have this bike the more things I find wrong with it. I don't mind fixing them, but sometimes it gets expensive. The latest one I found yesterday cruising (read: "flying") down the highway. In E-gear (overdrive I think?), going up a slight hill at 80-85 I could hear a weird sound coming from the front half the bike - maybe underneath me. It sounded like a mix between an airplane sputtering about to stall and a metallic grinding. I didn't feel a lack of power during this. Confused I let off the throttle and the noise went away. I pulled harder on the throttle and it came back louder til I heard some sort of pop and I could have sworn I felt something fly past my left foot. The pop sounded like a cough and had a bump of power loss, and looking back I didn't see anything fly off the bike. Startled, I let off the throttle immediately. The bike continued to ride fine. Nervous, I didn't test it anymore. Today I was going down the same road and wanted to see if I could get it to do it again. And I got the same results, though I didn't pull hard enough to get the pop-cough. I got the sputtering/grinding and I stopped before it got worse.

    My first thought was some sort of engine trouble, but now I'm thinking it's the transmission, since I've never heard it in any other gear and only does it under heavy load (80+mph). I also think maybe the thing flying past my foot with the gear shifter twitching with the transmission spazzing out. Has anyone else had similar problems or know what could cause something like this? What is likely wrong, and is my bike going to detonate anytime soon?

    Ben
    #1
  2. Zoef zoef

    Zoef zoef Been here awhile

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    Sir,

    It sounds like your engine is knocking/pinging. Depending on the hill, next time you might want to try it in 5th gear, see what happens then.
    #2
  3. jdgmntDay

    jdgmntDay Adventurer

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    Revivng an old thread from the graveyard here, but I haven't for sure nailed down my problem and how to fix it yet.

    It's not just 6th (Eth) drive, it's any gear in which I ride with high RPM and high load. I have tried switching the ignition cables to the spark plugs - one looked a little cracked or worn and had a touch higher resistance. My thinking was if one wire had just a bit too much resistance that the spark would not reliably ignite the cylinder, then switching the cables should move my problem. That did not fix it.

    I tried switching fuel injectors from one side to the other, thinking one might be plugged or spray differently or something wrong with them. Did not move the problem.

    I pulled the ignition coil out and measured the resistance across the primary and it was normal at .5 Ohms. The secondary resistance however is a bit perplexing - my measured resistance with a Fluke meter at the coil (not the end of the wires) was 7600 Ohms. My Clymer manual says the secondary resistance on my single spark bike should be 1300 Ohms. That makes it sound defective, however, further down the chart it says the secondary resistance for "secondary spark plugs with traditional ignition coil" is 7500 Ohms. Now I'm thinking this is somehow the wrong ignition coil for my '00 single spark bike. It also says in the book if I pull the spark plug out, ground it to the cylinder head and watch it as I turn the bike over while doing a compression check, I should see a fat blue spark shoot off the plug. I barely see anything, let alone a fat blue spark. This might also be causing the minute surging problem my bike also has.

    So I pulled the part number off the ignition coil and looked up the part number on the MAX BMW microfiche of what's supposed to be on my bike, and they're the same. So where is this miracle 1300 Ohm coil coming from, where can I get one, and do you think it would solve my problem?

    I've also talked to a dealer about this, but his knee jerk reaction was to pull the heads off and clean out the compression chamber. That sounds like big dollars to pay him to do (I don't have a garage to work on this, and as soon as I pulled the heads off, inevitably a rainstorm and dust storm would break the laws of nature and happen at the same time), and it seems like overkill. I want to try everything I can for free first. Modifying this, switching that, etc so I can really narrow down my problem before having a dealer fix it.

    I saw a good deal on EuroMotoElectrics for ignition coil and cables, so I could just buy them and swap them out whether they need it or not, but I could think of better ways to blow close to $150 if it turns out to not help.
    #3
  4. mouthfulloflake

    mouthfulloflake Not afraid

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    That sounds like pre-detonation-pinging to me, what octane fuel are you running?

    the surging thing is a historically known and celebrated feature of this lineage of bikes.
    #4
  5. GS Addict

    GS Addict Pepperfool

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    +1
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  6. Callisto224

    Callisto224 Long timer

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    Like a previous post asked, what octane are you running?

    Also, how many miles are on your 2000 1150?

    When was the last time you changed the plugs?

    If it only happens under heavy load it's probably pinging.
    #6
  7. def

    def Ginger th wonder dog

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    Secondary coil resistance is ~7.5K ohms cold.

    Also, many oilhead boxer owners use Autolite 3923 plugs (the plain ones...no iridium, platinum or gold plated versions...the $2.00 each version...mine are 10 years old and still work like new) and report improved performance.

    Perform a compression check to determine if you have excessive carbon. Don't remove the heads just yet until you know the cause of your problem.

    Finally, you might try running the valve lash a bit loose, say a couple thousandths of an inch at each valve. This will decrease effective compression and may solve the problem.
    #7
  8. BluByU

    BluByU Been here awhile

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    OK, What is the proper range of a compression check?? I did my 04 R1150GSA last week after valve adj and came up with 240psi in both cylinders (seemed rather high to me but both cylinder were the same) and after reading this thread I have to ask what is the factory spec?
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  9. mouthfulloflake

    mouthfulloflake Not afraid

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  10. GS Addict

    GS Addict Pepperfool

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    Autolite 3922 are used on the 1150 engines, the 3923 is for the 1100's
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  11. vintagerider

    vintagerider Long timer

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    metallic grinding
    Pre-ignition or pinging is a distinctive clatter. May have u joint/drive shaft issue. If that is the case then repair before it fails. btw 160 is normal compression
    #11
  12. roger 04 rt

    roger 04 rt Long timer

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    There is a real possibility that your in-tank hoses are cracked and leaking, your fuel filter is clogged or your fuel pump is weak. The noise you describe sounds like pre-ignition. Also your engine may be misfiring which will overheat your cat.

    At idle, try measuring the return flow of fuel to the tank. If you get about 2 liters per minute your in tank stuff is okay. Or you can open the tank and inspect.
    #12
  13. Jim Moore

    Jim Moore Long timer

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    Your coil is fine. The 13K spec was a misprint in the original manual that no one has ever bothered to fix.

    Pinging sounds like you are shaking a bunch of BBs in a coffee can. If it's bad enough you will also feel a slight stumble or power reduction. Your model is susceptible to pinging in hot weather at 4000-6000 rpm at full throttle, especially at high elevation.

    People have tried all sorts of things to rid the bike of pinging. I finally cured mine by installing a set of RT intake tubes. You can prbably find a cheap set at bmwsporttouring.com. Lots of RT folks put GS tubes in their RTs, so there are lots of them sitting in garages.
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  14. roger 04 rt

    roger 04 rt Long timer

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    [​IMG]
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  15. def

    def Ginger th wonder dog

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    The 3923s are one range hotter than the 3922s. I have used both but now just stick with the 3923s in my 2001 R1150GS.

    Plug color is correct and has been for almost a decade with the same 3923s. They cost me $1.00 each back when with a mail-in rebate coupon.
    #15
  16. def

    def Ginger th wonder dog

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    From my BMW REProm, 2001 GS;

    Compression test pressure

    good..... bar (psi) above 10 (142)
    normal..... bar (psi) 8.5 ... 10 (121 ... 142)
    poor..... bar (psi) below 8.5 (121)



    If you're reading much above 150PSI, I would suspect combustion chamber deposits which often lead to detonation and can also lead to engine damage (hole in piston). Have a peek in the spark plug hole with a scope. Also, you can remove TBs and get a look at the back side of the intake valves. If you observe oily, black carbon deposits, repairs are in order.
    #16
  17. roger 04 rt

    roger 04 rt Long timer

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    His symptoms also exactly mimic fuel starvation due to the higher power/fuel demands of trying to accelerate at 80. The return volume test is pretty easy.
    #17
  18. jdgmntDay

    jdgmntDay Adventurer

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    Wow, these are great responses. I've got some questions to answer here first, so here goes:

    I'm running premium fuel always, so it's 91-93 octane depending on where I get it. I've been running this problem past my dad and he asked if there's alcohol in the fuel I'm buying. I'd never given alcohol a thought, but I'll pay attention next time I fill up.

    This bike has 143k miles on it.

    The spark plugs are regular Autolite 3923's and 6k miles old, but I don't remember what they're gapped at. I'm thinking it's .035", but maybe as low as .020".

    Last time I did a compression check it, I got 160 to 163 on both sides (ran multiple tests for accuracy).

    I haven't tried anything fuel tank related yet, and I got the bike with 133k miles on it and without much paperwork. Thus, I have no idea when/if the pump has been replaced or if the hoses are any good. I can give the 2-liter bottle test a try.

    The noise definitely starts to show up at around 3.75-4k, and I don't run it past 6 ever. I once tried to power through the noise to see what would happen. I heard a much louder pop and felt a definite stumble. I didn't want to do that again for fear or personal or property damage, so I backed off.

    It also does seem to be intermittent, happening maybe 60% of the time. The other 40% it seems to work fine. I can bury the throttle and though the bike won't take off like a rocket (another post has informed me my '00 1150 has the tallest of overdrives for the GS's), it won't stutter or sound like anything out of the ordinary. I haven't yet deduced if this is temperature related. That is another test I can do fairly easily: try hammering the motor when it's stone cold and try again when it's a little on the hot side.

    It sounds an awful lot like the pinging you guys are describing. My dad suggested using a makeshift stethoscope out of some vinyl hosing to make sure it's pinging; that sounds like a pretty good idea. He also suggested to try playing with the spark plug gaps, starting with a wider gap to see if my problem gets way worse, then narrowing it to see if it gets better.

    Jim, the RT intake tube sounds like a clever idea. I'm assuming the RT tubes are narrower, letting in less air, therefore richening the mixture and cooling the chambers (at the expense of power, but I'm okay with that as long as it runs smooth). Is this the case?

    Thanks for all the great advice you guys are giving me.
    Ben
    #18
  19. roger 04 rt

    roger 04 rt Long timer

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    Ben,
    You've done a really thorough job of explaining your problem. It still sounds to me like you have a fuel problem. Here's what seems to me to be happening:

    At 3600 rpm in 6th at 80 mph on level ground your engine is producing about 25 HP and your fuel injectors are firing every revolution for about 3.5 mS (from memory). When you ride into a headwind, uphill, or accelerate the injector pulses lengthen and in the case of accelerating go to almost 8 mS, twice as long. So your fuel system has to deliver, in the case of accelerating, almost twice as much fuel. But it can't, because something is wrong--pump, filter or hoses. (Less likely: very clogged injectors)

    Figure this out before you damage your motor. Make that return volume test and you'll rule in or out many possibilities.

    Btw, what color Coding Plug is in your electrical box? Someone might have changed it.

    Regarding the RT tubes, they have a larger diameter and are shorter. Even if they were narrower, the Motronic, your fueling computer, would learn through closed loop fueling and adaptation that it needed less fuel, and you'd be back where you started.
    #19
  20. mouthfulloflake

    mouthfulloflake Not afraid

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    its does sound as if you need to go into the tank, that rubber U hose seems to rot in as little as a few years at depending on fuel.

    also, to help eliminate the pinging, it takes about 10 minutes to retard the timing under the black front cover on the engine

    I did mine while grilling a steak camping a couple of months ago ( i change mine seasonally to match temp to help minimize the pinging)
    #20