1988 R100GS questions

Discussion in 'Airheads' started by manybike, Dec 30, 2011.

  1. manybike

    manybike Omnipresent

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    I am looking at a 88 R100GS, have not yet physically inspected it yet but here is the scoop.
    It has Mikuni carbs with K&N cones. In the photos it looks very good, extra 21" front wheel and bags etc.
    The owner is sending photos along with history of maintenance and mods.
    However....he is claiming 90 hp from the engine. I have owned several airheads but 90hp seems a bit of a stretch.
    Is this type of HP even possible and still have a reliable engine?


    Were the 88 GS's a good bike compared to the later 90's versions?
    Any comments (even snide ones), analysis or anecdotal input appreciated.
    #1
  2. Stagehand

    Stagehand Imperfectionist

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    88's are great. They are practically indistinguishable from later models except for the handlebar switches and maybe the steering neck bearing arrangement. Cones suck :lol3 90 horse is very optimistic. They put out 60 at best, maybe the guy read it upside down? :lol3
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  3. manybike

    manybike Omnipresent

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    Why do the cones suck? what problems would you encounter with them?
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  4. Stagehand

    Stagehand Imperfectionist

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    I have no personal experience with them, but know they take in water much more easily than not, and I dont know how weird they are to jet properly. I know the GS's act kinda funny of you even mess with the asymmetrical intake cones on the stock setup. I also just dont like cones :D but that of course is just one knuckleheads opinion. (mine)
    #4
  5. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    If your going to put the bike through it's paces in water and dusty conditions then go back to the stock filtration. The filters on it now will get lots more dirt and water. Try and get the old setup, hopefully the PO kept the carbs and stuff. If not that will cost some major bucks to locate!!!

    90 HP....what sort of kool aid is the guy drinking....no way. I like the older bikes as there is less plastic. The headset is easier to adjust on the later airheads, but that's a minor difference.
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    The pre 1990 models are nice because of the minimal bodywork. Much easier to access the headlight and everything up front. They're also a bit lighter without all that macho bodywork.

    But otherwise they're all pretty much the same.

    A carb change and pod filters won't give you 90 HP. :lol3

    The mikunis only make the engine more responsive. And from all I've heard, messing around with the intake tract tends to reduce HP or give serious flat spots.

    I'd be cautious and find out what other changes were made to the bike - just my gut feeling.
    #6
  7. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Yeah, find out about the engine, if it was modified with a cam and higher compression. If modified better find out specifics and who did the work and it better be someone very reputable!!! Personally I wouldn't have a GS if the compression was raised as that will limit what gas should be used. I like the low compression of the GS as it does just fine on 87 octane.
    #7
  8. fishkens

    fishkens Long timer

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    +1

    I like my '88. Bought it new and it's done everything that I've asked of it.

    Mods to get it to 90 hp (if that's even possible) would be pretty extreme and would most likely compromise daily, long-term reliability and rideability.

    I'm a fan of the stock airbox and carbs because it's stupid simple (a big plus for me :lol3) to keep the bike running the way it was designed to run which I'm also a fan of. I've added 9.5:1 pistons but otherwise left the engine pretty stock.

    Is the other front wheel oem or a aftermarket rim? It's been said that good aftermarket rims are stonger and lighter.

    How many miles? Has the driveshaft been replaced? The Valeo starter can crap out if it's original but that's an easy fix (updated Valeo or an old Bosch).

    A pic from the WA backcountry discovery route...
    [​IMG]
    #8
  9. manybike

    manybike Omnipresent

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    Yep, I intend to find out what all was done to the engine, and you are totally right....who did the work!

    I am not a real cone fan either...not sure how hard it is to get a pair of old bings and a air box.
    For just forestry road stuff the cones would probably be okay but water crossings could be difficult.

    It's kind of a shame because the rest of the bike appears to be in beautiful condition.

    I am also suspicious of the 90 hp claim...I just can't imagine what you could possibly do to attain that.

    The price of the airhead GS series seems to get a little higher each year.

    I don't even know why I want another airhead...I have owned two others that have been great easy to maintain bikes that are fun to ride, attract a lot of attention and....am I starting to answer my own questions??
    #9
  10. manybike

    manybike Omnipresent

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    I don't have any detail yet on the full history of the bike, this is being sent to me via snail mail.
    The current owner is not the one who did all the motor work which was done in California by the PO. I am hoping that he has all the documentation.
    With luck I was hoping that another inmate might be familiar with the bike....ya never know!
    #10
  11. manybike

    manybike Omnipresent

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    Here is a photo...if I get this right

    [​IMG]

    It has 40mm Mikuni flatsides, Remus exhaust and HD advance ignition.

    Opinions??
    #11
  12. fishkens

    fishkens Long timer

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    circa 1989 low front fender.

    Where does the crankcase breather go? Looks like a hose to somewhere? Plenty of people do that.

    The shock has been upgraded to the WP (?) oem shock (good).

    Not dual plugged which makes claims of significantly increased hp more suspicious.

    Looks like a nice bike if priced fairly.
    #12
  13. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Not a bad looking bike at all.

    Getting down to specifics - an airbox will run you about thirty or forty bucks.

    Carbs - probably a couple hundred - maybe twofifty with cables.

    I'll bet the PO PO got rid of the airbox because of the problems hooking up air tubes to the Mikunis. And I think 40mm carbs are too big for the bike. I'm sure low end grunt is anemic due to that.

    Otherwise it looks good. If you need help on figuring out a fair price, give us the mileage, major work done like transmission or driveshaft, what all comes with it and asking price.
    #13
  14. manybike

    manybike Omnipresent

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    The owner was asking around $6K which may be on the high side, although I just sold my 82 R100 for $5.4k.
    I will know more this week when I get all the details on what work and mods have been completed on the bike.

    There seems to be a fairly broad price range on these bikes but from what I have seen they generally sell between about $4.5k to $5.5k ......depending on a lot of various factors.

    I will let you all know more details once I get them...I would like to get opinions on pricing

    Thanks all
    #14
  15. AK Bob

    AK Bob AKAM

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    I have an '88 GS but its white, so probably a lot slower..

    The Original 32 MM Bings (assuming a US bike) were jetted LEAN. It is the same motor that was on the Euro bikes that had 40 MM carbs, and no AirPulse System. Don't know about the Eruo exhaust system for stock bikes.

    Be real Careful! I have doubts about the seller. He is sincerly mistaken at best. 90 HP ? OK, I'll say it Bull Shit! Is it Dual Pluged and on Aviation gas or race Fuel, where does the Blower hook up or is it a turbo? Next question WHY? The GS is a tractor, not a RR and it never will or should be. The drive Shaft is a weak point as it is, adding that much HP isn't going to help. The lack of the regular airbox and crankcase breather concerns me, The ammount of dirt that I pick up on the haul road and other gravel roads would toast the cone system. What is keeping dirt out of the crankcase breather? The front fender is not original, so look the forks over real close.

    How many miles are on the bike? Bought mine for $5.3 K and it had 12K miles on it. Put about 700 more in it fixing stuff. Now I'm just adding Farkels.

    If your not a member Join the Airhead Beemer Club. Lots of guys just like to help.
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  16. manybike

    manybike Omnipresent

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    Thanks for the info AK

    Yes, I will have to give it a very close look over.
    I have been able to zoom in the photo, you can see a crank breather hose running from the top of the engine to somewhere under the seat where I imagine it has a small filter attached.

    They had 60hp out of the box, I think at best you could maybe get another 5hp or so from the mods that have been done. I think the 90hp claim is simply incorrect (could have been a typo or something in the message that was sent to me)

    Thanks for the input.
    #16