Dying R100 GS

Discussion in 'Airheads' started by alvincullumyork, Feb 26, 2012.

  1. alvincullumyork

    alvincullumyork I wish I was cool

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    Me and my brother decided to buy a 92 R100 GS. From that point on I sort of wish we had bought a KLR or something else(the gs is so stinking cool though). On to the problems. My brother had it for a couple of weeks down in California and took if for a couple of rides and the battery light started to come on pretty consistently. A few weeks later I went down so see him off ( got deployed to A-Stan) and bring the bike home. The bike sat for a couple more weeks until I got the paper work sorted out then I started riding it and the battery problem got worse until it died a mile from home one night (pushed it back in eleven minutes flat). Being that electrical stuff is all voodoo to me I took it up to the BMW dealer and had them fix it.

    I got it back and it ran pretty good but it would randomly loose a lot of power, almost like one cylinder wasn't getting gas. I could throttle way up and it would slowly gain rpm and just barely accelerate. After a while it would surge between bad and good and then clear up and ride like normal. Other times it would just die but it would start up after little playing with the choke. It is also only getting about 20mpg. I went for a 50 mile ride yesterday and no problems until it died 3 miles from home. I switched the the fuel valves to reserve and got it fired back up but just barely and limped it home. Now it just won't start at all and there is barely any gas left in the tank after a total of 111 mile since the last fill up. Right before I took it up to the BMW dealer I put a tank of premium through it, I'm not sure if this could be part of the problem or not.

    Please help me before I go insane.
    #1
  2. R100LT

    R100LT Chasing 11

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    Well the charging issue seems to have been fixed ... so with bad fuel economy and losing power the first place to look is the carbs.

    How long was the bike sitting before you and your brother bought it ???

    PS ... Which is the Non Rainy side of Oregon ??? Thats a bit like " Keep Portland Weird " ( is there any danger of that actually NOT happening ??? )
    #2
  3. alvincullumyork

    alvincullumyork I wish I was cool

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    The guy we bought it from started it up and rode around every once and a while, by all appearances he took it very good care of it and was very helpful to my brother. I have this horrible feeling my problems have something to do with the premium gas I put through it.

    It doesn't rain all that much in Eastern Oregon (Gods Country). There are real mountains, beautiful sunsets, and very few of the bad kind of hippies.
    #3
  4. R100RT Mark

    R100RT Mark Been here awhile

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    Lots of places you could start.

    Budget approach is probably as follows. You should plan to complete all steps in any event as a basic starting maintenance for a bike with uncertain history. As well as these running quality matters, oil changes, brake checks, etc. should be at the top of your getting-acquainted list.

    A - Check springs on the “choke” enrichers are installed and working. If not, correct. Cost less than $10.

    B – The next simple “little skill needed” action would be to empty/clean out the gas tank, clean the petcocks/petcock filters, and fit new fuel hose. There is a somewhat counter-intuitive knack to removing/installing the petcocks – just persevere and do not force anything back together. Probably will not, but there is an outside chance that this could cure all your ills. Certainly will not hurt. Likely cost of parts about $10 for fuel line.

    C - Next step, and probably closer to a cure, would be a carburetor “freshening.” Certainly new gaskets, O-rings (maybe not the throttle shaft O-rings), and float needles. Possibly new floats. Replace the air filter if clogged. Simple if you pay attention and work on one carburetor at a time to avoid mixing parts. Get a Haynes or Clymer manual and check the online gurus missives on the subject. Parts cost for this stage: aftermarket two-carb refurb. diaphragm and gasket/O-ring kit about $30, float needle about $35 for two, floats about $50 for two. If this does not get close to a complete cure, you have bigger problems than can be sorted by simple maintenance-type tasks.

    D - After that, if “cured” or close, timing, valve clearances, mixture adjustment (again), and carb. balancing etc. to get truly happy. If not then fully cured, things get a little more complicated.

    Mark
    #4
  5. ignatz72

    ignatz72 call me iggy

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    You did ABSOLUTELY no damage to the bike by putting 93 octane in it, as a matter of fact that is what you should always put in it.

    Your problems are likely related to the fact that the bike has been sitting for more of its life than it has been running.

    You didn't mention how many miles it had on it, but like R100LT mentioned, it would also be good to know how long it has been sitting (or "started up every month and run around the block").

    Gas goes bad, and bad gas does bad things to the fuel tank and carbuerators... You probably have a gas tank liner and rust issue, as well as carbs that have either not been tuned in a decade or have been tuned to the bad gas scenario.

    Fuel supply (gas tank, petcocks, fuel line) and fuel preparation (carbs) are your first suspects.

    A search here, or research of the following websites will aid your progress:

    http://largiader.com/

    http://bmwmotorcycletech.info/technical-articles-list.htm
    (scroll down until you see the numbered list start)
    #5
  6. R100LT

    R100LT Chasing 11

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    One tank of premium wouldn't probably do it unless it was from a Service Station in Mexico . More likely there was some form of crud in the tank.

    What I normally do when I get a new bike is a quick service of changing fluids , oils , filters and plugs. That can give a decent visual of the history and what you might expect to find in the future. In regards to economy ... that can range from riding style ( I am hopeless in that area ... always think the throttle has two positions ... off or totally open ) to even the most silliest of things ... like accidently kicking the bowl on the carb with your foot and almost running out off juice in the middle of nowhere )

    PS Never got too far East in Oregon . Did do a wonderful "loop" in two days where we rode 1500 miles up past Mt Hood , down through Bend, into Klamath Falls and Clear Lake, then back up the coast to Portland. Totally loved the town Ashland. New experience riding in snow for me.
    #6
  7. batoutoflahonda

    batoutoflahonda Long timer

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    what others are saying. Just do a basic tune up. Including the valves, air filter and carb sync.

    When I first got my G/S it would sputter and quit. Would only restart after a healthy back fire (after fire actually). Got horrible gas mileage and struggled up hill. Found the PO had not turned the motor when the valve gap was set, (essentially it was running on one cylinder, and it ran great, except for the a fore mentioned) . Really screwed with my head for a bit as I thought I was not setting the valves right. Finally tossed out what I was seeing for what I knew, and it ran great.

    Airheads are extremely resilient bikes and good at hiding miner problems. Heck, I had a hole in a valve and it ran great on flat ground.
    #7
  8. alvincullumyork

    alvincullumyork I wish I was cool

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    The bike has 39,000 miles on it.

    I was thinking about replacing the fuel lines as they look a little dated. Is there a special type/size of fuel line I should buy? I was just going to go to Shucks and buy some fuel line. How hard is the crossover line to get to? It looks fairly straight forward, take the seat off, take the tank off, then the air box?

    How would I go about checking the springs on the the choke enrichers? I am very new to this.

    What would be the best place to buy a carb rebuild kit?

    The dealership replaced both fuel filters and looked at the right side card to fix a minor leak. I was thinking about taking the tank off and cleaning it out with gas. My friend also recommended putting carburetor cleaning additive to my next tank of gas.

    It might be a while before I get to do anything due to rain and lack of a garage and those stupid classes I'm supposed to fit in between shooting, riding, hiking, running, you know the important stuff.

    ignatz72 Thanks for those site. There is a lot of information on those two sites.

    R100RT Mark thank you for the list that helps a lot.

    To everyone else thank you for your help and hopefully continued help. So far this has been a friendly and helpful forum, which has been rare in my experience.
    #8
  9. R100RT Mark

    R100RT Mark Been here awhile

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    1/4" automotive fuel line works fine, but is typically a little larger OD than stock (tends to be stouter than we need as it is sold on the expectation it will/could be used on pressurized systems). You should be able to route the crossover without too much difficulty.

    The Bing Exploded View here http://www.bingcarburetor.com/pdf/MOTORCYCLE%20CV%20EXPLODED%20VIEW.pdf should help you see what's what. If "the dealership" has tinkered with the carbs to cure a fuel leak etc. as you mention, they should have seen if the choke springs were missing and corrected this already.

    EUBMW http://www.eubmw.com/Carb.html

    My guess is that the dealership replaced the aftermarket in-line fuel filters commonly used on airheads. The filters that need checking/cleaning are the ones in the gas tank held in by the petcocks.

    Yes, take the gas tank off and clean. You could well have water in the gas. At a minimum, "drop" the float bowls at the same time.

    Carburetor cleaning additive in the gas will not do anything other than to relieve your wallet of a few dollars.

    You will get a lot of help, but you also need to help yourself. Get a manual. Read the on-line gurus.

    Mark
    #9
  10. alvincullumyork

    alvincullumyork I wish I was cool

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    I know I'm just a slightly overwhelmed and considerably under funded. Your help is much appreciated.

    I will try and do some of the things you guys listed and report back with hopefully good news.
    #10
  11. hardwaregrrl

    hardwaregrrl ignore list

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    Hey Alvin, if you drop the float bowls you may also want to check that your float levels are correct. You could measure or just eyeball it. If you take the float bowl off, push the floats up. Then turn on a petcock, drop the float until gas pours out. You want the gas to start flowing when the float is parellel to the carb body.

    look here
    #11
  12. photomd

    photomd Been here awhile

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    Joining Airhead Beemers Club or hooking up with some people in your area would be a good idea as well. IMHO, you need to clean the system from the tank to the carbs and go through the carbs to get the most out of the bike. If the carbs have never been rebuilt or you don't know, I'd replace all the rubber parts. This includes the o-rings, diaphrams, check your floats, intake manifold rubbers, etc. That way you'll know you have a reliable bike. My experience with bikes that sit is that you're better off spending the money up front to make it relaible than chasing your tail.

    If you're getting 20 mpg, I doubt you're flowing enough fuel. Oak gives a flow rate for 30 mgp which works out to 8oz/minute. You can test that, but your mileage is an indication of something else as well. You could have a partially clogged vent (if this fuel starvation is reproducible, take your gas cap off and see if it does it). It could be the fuel screens on the petcocks, air leaks at the intake, air leaks in the throttle shaft, leaking enricher (choke), float level incorrect, or a little hole in a diaphram. My bet would be the diaphrams as they'll surge and sometimes lift a little with a small tear. Air leaks will also surge and slowly rev as the fuel mixture leans out. Air leaks will also surge if it's one cylinder. Clogged vents and poor fuel flow is like hitting a rev limiter as you run outta fuel.

    Good luck. I think getting someone in your area to help will not only teach you about the bike and carbs in general, but you'll probably find someone fun to go ride with. :freaky
    #12
  13. 97oilhead

    97oilhead Been here awhile

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    #13
  14. Tagman

    Tagman JCunningham San Carlos, Mexico

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    Also,Check your coils for cracks, My sons 89 GSPD reacted the same way when he bought it. Humidity changes in the air would short out 1 coil.
    #14
  15. darklight79

    darklight79 drink it , ride it , nail it

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    Buy a book or Ill will send you a copy of the bmw owners manual ..SEnd me a pm with your email. dude , you let the dealer put fuel filters on ? You have one of the easiest machines in the world to fix or sell to me lol stu and stay away from the E10 fuel that oregon is so proud of BMWS hate that stuff
    #15
  16. Wirespokes

    Wirespokes Beemerholics Anonymous

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    You're obviously flowing way too much fuel, unless you're pushing the bike harder than Supershaft (one of our 'hard riding' inmates here). :D

    Simple first steps would be checking the fuel level in the float bowls (should be about 1/2" down from the lip) - it's probably a LOT higher than that. Adjust the floats or figure out why it's high. Next would be to inspect the choke bodies to make sure they're secure with no loose mounting screws or sucked-in gaskets. Make sure the chokes turn off all the way.

    Running premium gas won't hurt the bike in the slightest.

    Where-abouts in Oregon are you located? The rainy side is actually quite large - probably a third of the state - everything west of the Cascades. :wink:
    #16
  17. alvincullumyork

    alvincullumyork I wish I was cool

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    I'm in Corvallis going to OSU. If any inmates are around and would like to swing by and see what I got, I would probably pee myself with joy.

    I have the owners manual and one other simple how to book but I think it might be in my brothers storage unit in California.

    The hard part is finding time and a covered space to do anything.

    eta: Okay, I might not pee myself.
    #17
  18. Beemerguru

    Beemerguru Beemerguru...G/S guy

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    Head down to Eugene and find an inmate named Alaine..just finished building an early '80s R80G/SPD Paris Dakar replica for him. Great guy and you two could learn about G/Ss.

    Start with the simple cheap things...check the gas, see what's leaking, learn how to adjust the valves, adjust the carbs. Timing never changes unless it breaks. Check the cables. Like all the other advice on this list...start with easy things first.
    #18
  19. supershaft

    supershaft because I can

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    What everybody has said. It could be almost anything but nobody has mentioned the battery. It could be a bad battery. Check cranking volts and charging volts. My next guess would also be the gray crack-o-matic coil.
    #19
  20. Padmei

    Padmei enamoured

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    I received the Bing book this week & read it thru. It is an excellent read & explains the carb circuits & what each component does & why.
    I'd really recommend you read the book before you start rebuilding your carbs (or while you are doing it) as it really puts an explanation to what you're replacing & cleaning. I wish i had read it a year ago.
    #20