Results 1 to 8 of 8

Thread: Quality differences by years?

  1. #1
    On the Road
    Join Date
    May 2005
    Location
    Manitowoc, WI
    Posts
    32

    Quality differences by years?

    I am now looking to get a strong dependable R100RT for my wife and I to take 500 mile weekend tours with. We want a dependable, high quality comfortable cycle that will be relatively inexpensive to maintain. Are there any particular years, ages, features or mileages that I should try to get or to avoid? Or is it strictly a matter of lowest mileage? Or latest year? Or best maintained/serviced? Or all of the above?

  2. #2
    Registered User
    Join Date
    Mar 2003
    Location
    Port Angeles WA
    Posts
    1,429
    Wow! You're asking for a lot of answers, and there are probably as many opinions as owners. However, I'm bored tonight, so I'll give it a shot.

    First off, let's note that the last R100 to roll off the assembly line was about 1995. When you mention "reliable", it's probably an oxymoron to say "ten year old bike" and "reliable" in the same breath. The R100 was relatively reliable in it's day, but there are several well-known problems.

    That also gets us to "economical". Used BMWs are pricey (compared to other brands) and if you then have to do some "things" to it, it's not going to be cheap.

    In the long run, (yeh, I know it's heresy to say so on the airhead pages, but) you'd probably get more for your money buying a used R1150R (non ABS) oilhead, which you could then equip with whatever luggage and wind bashers your heart desires.

    However, if you just have to have an airhead, then let's note the primary problems: valves, charging system, rear main seal, flywheel, transmission, final drive, brakes.

    For longevity, the heads should be reworked to the latest valve specs. Of course, you could buy a late model, but you'd get some other things you might not want. The heads can be reworked for a few hundred bucks. Latest valves, seats, and guides.

    The charging system (all years) typically causes ongoing problems. Some airheads don't have problems, but most have weak charging systems, and it's not uncommon for sudden failures of rotors and diodes. The best fix is probably to swap over to the Omega system, which jacks up the output to about the same as a K100.

    BMW went through a number of rear main seals to find something that would do the job reliably. Any used airhead should have the transmission pulled and the clutch splines lubed, and at the same time the rear main seal can be changed to the latest design.

    Starting about 1982, BMW lightened the flywheel. Or rather, they substituted a cheap stamping for the previous cast/machined flywheel. The good news is that the engine changes RPM much quicker. The bad news is much more vibration. (some worse, some not too bad) I prefer the older, heavier flywheels, even though they require a bit more talent when shifting.

    For some obtuse reason, BMW eliminated a circlip in the transmissions of most 1986 to 1994 transmissions. Some brand new transmissions fail within a few thousand miles. The fix is to have the transmission torn down and the output shaft machined for a circlip--just like the older models. The 1995 transmission was OK. And earlier models were also OK, although there was a redesigned shifter linkage along the way that was an improvement.

    The old "double sided" swing arm had a shaft with one U-joint and a splined bell coupling. OK, the drive output had a spline coupling to the rear wheel that would gradually wear out. But basically, the old double sided swing arms allowed a long life for the driveline. When BMW changed to the Paralever, reliability went down the toilet. The Paralever driveshafts are good for about 40,000 miles, and the fix is to replace the shaft and both U-joints every 40,000 miles. So, if you're looking for economy and reliability, avoid anything with a Paralever final drive.

    Prior to around 1982, the airheads used "ATE" brake calipers that weren't great. The change to Brembo calipers was a tremendous improvement, involving different fork sliders. So, that's one reason to look for a 1982 to 1984 model. However, the drum rear brakes were fine, and didn't have the hydraulic problems of rear discs, even Brembos. So, given a choice, stick with the drum rear brake. And yes, a disc rear can be converted back to a drum rear wheel.

    That's enough for now.

    pmdave

  3. #3
    On the Road
    Join Date
    May 2005
    Location
    Manitowoc, WI
    Posts
    32

    Wow!!

    That was alot of very good info; but, thanks I needed that. I certainly hear what you are saying with looking to the oilhead for a more complete solution; very good advice it seems to be. The 82 RS I have for my own travels is good fun but for the miss's demands I suspect I'll move on to the more reliable oilhead.

    With out getting too detailed, any advice on those?

  4. #4
    rocketman
    Guest
    Quote Originally Posted by pmdave
    Wow! You're asking for a lot of answers, and there are probably as many opinions as owners. However, I'm bored tonight, so I'll give it a shot.

    First off, let's note that the last R100 to roll off the assembly line was about 1995. When you mention "reliable", it's probably an oxymoron to say "ten year old bike" and "reliable" in the same breath. The R100 was relatively reliable in it's day, but there are several well-known problems.
    Without trying to start a long drawn out discussion on the reliability issue of oilhead vs airhead, I do think that saying "ten year old bike" and "reliable" is oxymoron is an going a bit far. The fact that there are still so many BMW's 10-20 even 30 years old still on the road and still going the long haul testifies that they are in fact reliable.

    I have put 100 K on my 78 in the past 5 years with only one minor break-down that required assistance and even that i could have handled myself but choose to have the top end rebuilt so just had it hauled th 15 miles to the local airhead shop 'cause it was 34 deg. at the time and I didn't feel like tackling the timing problem in the cold.

    Quote Originally Posted by pmdave
    That also gets us to "economical". Used BMWs are pricey (compared to other brands) and if you then have to do some "things" to it, it's not going to be cheap.


    In the long run, (yeh, I know it's heresy to say so on the airhead pages, but) you'd probably get more for your money buying a used R1150R (non ABS) oilhead, which you could then equip with whatever luggage and wind bashers your heart desires.
    Actually an airhead can be had for anywhere from 2 to 4 K for late 70's to mid 80's in the R100 range, a bike capable of many highway or back road miles a day. And with the cost of parts being generally cheaper than Oilhead parts and still readily available the total cost of ownership for an airhead is still prob. less in the long run than an oilhead. Again i spent 2500 for my 78 R100 in 99 and have put around 2k into it since then (including the top end rebuild this spring) and have gotten over 100 K of riding since buying it. So 4500 for that many miles is pretty low cost of ownership. I know many other airhead riders who can atest to similar costs of ownership. I'll go anywhere for any distance without worry that I will arrive back home without mishap just as anyone on an oilhead would.

    Now I will qualify this by saying that I am aware that oilheads DO have certain advantages because of the technological advances since the 70's and 80's, more power, better brakes, prob. more comfort certainly more options and the ability to run more electrical options etc. but that comes at a cost. And yes, airheads do require more frequent maintenance but if you can do much of it yourself it does not impact cost of ownership very much, it's more a matter of personal time spent.

    Just another side of the story to consider. Both have their strengths and weaknesses, the rider has to decide in the end which has more value for their intended use/interest.

    RM

  5. #5
    Registered User R100RS's Avatar
    Join Date
    Jul 2003
    Location
    North Florida
    Posts
    435
    For dependable, high quality and reliable, I'd stick with a 1988 to 1995 model. That's assuming you're set on the RT. RT's never had paralever driveshafts, so that's not an issue. Supposedly, the monolevers handle better than the double-sided swingarms, but I doubt I can tell the difference. There is a big difference between the monolever (RS, RT) and the paralever (GS, R100). The paralevers do have driveshaft reliability issues, the monolevers don't.

    The later years they got most of the quirks ironed out. I have one of the "circlip-less" transmissions and have almost 80k on it without the tranny ever being opened (and no signs of internal wear, either).

    The charging system will be borderline. If well sorted out and you use it within its limits, it will work just fine. Once I got mine figured out (a Police model voltage regulator and sealed battery worked wonders for me), it has been very reliable (but I don't have heated grips or heated clothing or extra lighting).

    Heads are really only an issue for the 81(?) and earlier models, before they switched to hardened valve seats for use with unleaded gas.

    Once I got my '88 RS sorted out (a requirement for any used bike purchase, IMHO), it has been extremely reliable and pretty inexpensive to operate.
    -Mike

    '02 R1150R
    '88 R100RS

  6. #6
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    6,262
    Quote Originally Posted by R100RS
    Heads are really only an issue for the 81(?) and earlier models, before they switched to hardened valve seats for use with unleaded gas.
    Heads were an issue mostly on '81-'84 models, for which BMW indeed changed the exhaust valve seat materials, but got it wrong.

    ALL R100 '81-'84 will eventually require replacement exhaust valve seats AND replacement of exhaust valves themselves, as the improper seat material causes plastic distortion of the valves.

    On a less serious vein, R100 heads from '88-on featured smaller exhaust valves, as the previous heads had such large valve passages as to have perhaps not enough material to prevent long-term warping. Reduced performance is traded for some increase in reliability.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  7. #7
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    6,262
    Quote Originally Posted by pmdave
    Starting about 1982, BMW lightened the flywheel. Or rather, they substituted a cheap stamping for the previous cast/machined flywheel. The good news is that the engine changes RPM much quicker. The bad news is much more vibration. (some worse, some not too bad) I prefer the older, heavier flywheels, even though they require a bit more talent when shifting.
    Having owned both, I can report absolutely no change in vibration.

    This 1981 change made the Airhead a modern-day motorcycle, moving it from the realm of farm equipment to modern times. I would not for a nanosecond consider a heavy flywheel Airhead.

    The heavy flywheel was a remaining vestige of BMW's sidecar days, which ended in fact in 1969, as the 247-engined models were never approved for sidecar use.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  8. #8
    Registered User lkchris's Avatar
    Join Date
    Mar 2003
    Location
    Albuquerque, NM
    Posts
    6,262
    Quote Originally Posted by pmdave
    Prior to around 1982, the airheads used "ATE" brake calipers that weren't great. The change to Brembo calipers was a tremendous improvement, involving different fork sliders. So, that's one reason to look for a 1982 to 1984 model. However, the drum rear brakes were fine, and didn't have the hydraulic problems of rear discs, even Brembos. So, given a choice, stick with the drum rear brake. And yes, a disc rear can be converted back to a drum rear wheel.
    The significant changes occurred with 1981 models, rather than 1982.

    '81s are known as a having a few "first year" problems, including but not limited to sidestand/centerstand problems.

    There's not really much problem with rear disc brakes, the biggest being that this installation makes rear wheel removal a bit complicated.

    Since you'll basically never find front wire wheels for '81-on R100RTs, conversion to rear disc means a replacment rear snowflake wheel, as the drum is cast as part of the wheel. Not an insignificant change and a challenge to find a 20-year old wheel with drum surface usable.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •