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Thread: 88 K100RS Won't GO

  1. #1
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    88 K100RS Won't GO

    Hello everyone, thanks for reading; all comments will be appreciated.

    I have a bike that was running fine one minute and won't go anywhere the next.

    It's as if the clutch were slipping. On the center stand, engine running, trans in first the rear wheel will spin (can't stop it with your hands). Get off the stand still in first release the clutch and .... nothing ( no weird noise) engine keeps running but the bike doesn't move.

    I pulled the trans and replaced the entire clutch assembly, and it's still the same. I also do know how to adjust the clutch and it does have free play. I'm convinced that the clutch push rod is not jamming either because my adjustments show a difference in the free play as it should.

    I replaced drive shaft (thought maybe the rubber in the shaft went) and differential... no help.

    I'm now thinking it's a blown output shaft.

    Can anyone tell me how to confirm with out pulling the transmission again ( I figure I could turn the bolt holding the clutch carrier and see if the engine turns).

    Also while on the center stand and in any gear I can turn the rear wheel by hand with marginal resistance and the engine will not turn.

    Let me know what you think,

    Thanks

  2. #2
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    Tried something else...

    I just removed a piece of rubber that sits between the intermediate housing and the trans just under the starter.

    Once removed I can see the clutch assembly spinning when the bike is running. I can also see it come to a dead stop when I release the clutch with the front brake held in first gear.

    Am I right in assuming that this confirms that the output shaft is shot?

    Thanks in advance.

  3. #3
    A bozo on the bus deilenberger's Avatar
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    Hi Mindtrainer..

    Take a look at: http://www.realoem.com/bmw/showparts...81&hg=11&fg=21 - the "output shaft" - there is a hub (#10 - AKA ABSORBER GEAR WHEEL) that is part of this shaft. The gear on the hub is what's driven from the crankshaft on the engine. On the K100xx models - that gear was held to the hub with 6 rivets.

    These rivets have been known to fail - resulting in exactly what you described. BMW later made a modified shaft where the hub has 12 rivets. My WAG - based on what you saw in your second post is that the rivets have failed on yours. I believe it's possible to just see the gear if you remove the crankcase cover, but it's been a lot of years and my memory is vague. There may be some additional info on the Internet BMW Riders K-tech site (www.ibmwr.org - look for K-tech.)

    Question now is do you want to fix it? It's a big job, and the parts aren't inexpensive. If you really love the bike - and just have to fix it - I'd be of a mind to consider looking for a used engine and do a transplant. The engines don't go for a lot of $$ used since they rarely ever break. The parts alone list for > $700, and I've seen good engines go for $300 (and less actually.. sometimes much less..) It might be possible to get the rivets replaced, but I have no idea where to suggest looking for a place with that capability - or have custom made shoulder bolts made to replace them.. but I bet those solutions also would cost more than a good used engine.

    Good luck with it. Shame you replaced all the other parts unnecessarily - since a few photos posted here might have gotten you an evaluation of their condition by people familiar with them.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  4. #4
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    Thank you Don

    The bike actually belongs to a friend and he's in love with it.

    The body is in pathetic condition, and all his rotors are worn out not to mention the drive shaft is ready to go at the differential, and it's splines are sharp and on the verge of giving up as well. If ever there was a bike ready to be parted this is it.

    Rick's Bike.jpg

    This friend of mine is semi-retired with very limited income and is currently riding his bicycle. I on the other hand just happen to have a complete K100 motor siting under my work bench; and since this is the season....

    I'm going to bite the bullet and do the unreasonable and replace his motor.

    Happy holidays everyone...

  5. #5
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    Rivets in the oil...

    Just wanted to add this for informational purposes.

    While draining the oil from the motor several of the rivets fell out of it, confirming absolutely what Don has already said that the rivets in the output shaft have sheared.

    So now I know what a blown output shaft does to a K-bike. It don't go no more......

  6. #6
    NC Piedmont Rider ncstephen's Avatar
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    A thought
    Great thing you are considering.

    Might you want to post this over at ADVrider.com on the Special Ks and K bike riders threads and then post up thread of the project including progress, what you need and get as well as posting it here and perhaps a few other places. There might be folks who have some old parts that are still within specs left over from updates on other folks K100s. You could ask for donations of those to perhaps get the bike in better mechanical shape. It would be ashamed for all your work to go for a workable bike only to have the driveline fail in the next month and the bike just be sitting again.

    NCS
    03 K 1200RS (Black is Best)
    03 Honda RC51
    74 Honda CB750 K4

  7. #7
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by mindtrainer View Post
    Just wanted to add this for informational purposes.

    While draining the oil from the motor several of the rivets fell out of it, confirming absolutely what Don has already said that the rivets in the output shaft have sheared.

    So now I know what a blown output shaft does to a K-bike. It don't go no more......
    That's sort of the ultimate clue the gear came loose.. rivets in the oil pan.

    Good luck with the swap! And you might ask around, perhaps someone has a rear-drive and driveshaft sitting around from a wrecked or sold bike they could donate to the project. From the looks of the paint - it looks like that was the special edition blue/white RS.. are the rims white with pinstripes?
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  8. #8
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    Back on the Road

    Ricky just picked up his bike with the new motor.

    It started and ran surprisingly easy after I finally remembered to plug in the computer.

    Imagine all those screws and plugs were all correct and fine, and then it wouldn't start.

    I even checked for spark on a plug wire... heard the pump and no start. Funny thing is it's not the first time I forgot to connect the computer after a big job like this.

    Yes Don this is one of those anniversary editions but the white wheels were taken off a few months ago. He hit a pot hole with the front bending the rim and blowing the tire. I had a set of brand new mounted and balanced Shinko tires. So he left me his bald rear tire on the rear white rim. The front one made it to the recycling center after I hack-sawed off the tire.

    If anyone needs it just let me know I'll sell it cheap to a member of this site.

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