Should I, or shouldn't I ?

[nhmaf]

In spite of the economically-sketchy times, I've been keeping an eye out for an 'affordable' R90 or R100 airhead in decent mechanical condition (some TLC needs acceptable) to eventually pair up with a sidecar of some sort and I came across this 1979 R100 for sale less than 1 mile from my best friend's house (200 miles from my house), tho).

It has had a long life (107K miles) but has been apparently reasonably maintained, and just had a full front to back go through by Max BMW in 2009.  The seller put some new on/off tires on it for dirt road riding, but it does also comes with nice condition Krauser bags and bolt on rear luggage rack, Dyna ignition, nice leather Corbin seat and Works rear shocks.  His reason for selling it is that he has several young kids and has no time to ride it - I took it for a spin and it seems pretty good, though in need of some front caliper adjustment/cleaning, I think and some other small items.  The odometer is working well, but as usual, the speedometer is completely wacko (indicated between 50 and 75 when I know I was doing about 40)..  Am I a complete fool for thinking of paying $2500 for it?

[Bengt_Phorqs]

Definitely not a complete fool.  That's about an average price, but at that mileage will you need to refresh the heads and maybe pistons?  Figure adding a sidecar to it done right will run at least another $5k.  If you can pick it up for a few hundred less that would at least defray some cost like the speedo.  Hey, it's only money and the project is the most part of the fun.  At least that's what I keep telling myself.

[nhmaf]

Unfortunately, the seller doesn't have any documentation for work done on the heads or for a transmission rebuild, but it does seem to shift well (for an airhead) and makes no out of the ordinary sounds.    The engine took a while to get it to idle well @ first - once it was good and warm it idled nicely, if a bit fast @ 1500 RPM and pulled very strongly without hesitation - so maybe the heads are OK for awhile, or have been redone (I'd tend to think so at that mileage, and given that the guy bought it from Emerson's (somewhat reputable shop - article in recent BMWMOA magazine) 4 years ago and had it fully gone through at Max BMW last year - and he's apparently only ridden the bike about 5K miles in 4 years, and has only had ridden it 3X all this year.   Among replacing cables, check and lubing splines, Max did a full rebuild of the carbs, according to the owner's documentation.

[suecanada]

Well, Mike, you have been chomping at the bit to get into a sidecar and with your abilities mechanically, this bike would suit a hack. Having had Max's behind the work..esp. those yukky spline jobs etc and the detailed carb work, I'd say go for it if you can. Maybe as Bengt says try to bid a bit lower as this is usual practise. A Corbin seat would be well worth it to have as will be a rear rack and it has the engine guards too. You guys always tell me not to worry about things that have no basis in fact..like a transmission that shifts smoothly with smooth residue on the drain plug...and I'm worrying about it giving up the ghost suddenly. You have the ability to tackle whatever issue that arises with the bike and you know you want it!
Ask Tillie!! That Concours may be looking for a new home? Tillie wants a brother!!

[nhmaf]

I think I'll call him and and make him an offer on Friday.  I may be foolish, but I'm not a complete fool (some small parts are missing)..

This could make things a bit tight in the garage with (3) bikes and (2) cars, but if I clean up the garage, move the lawnmower and some other stuff into the barn, I think I might just have enough room to add a sidecar's width in there sometime in the near future..hmmm

[Semper Gumby]

Of course you should!

What kind of tires are on that bike?

[nhmaf]

Ended up giving $2400 for it - I could have probably knocked another $100 or so off it but decided not to press too hard as the young guy's wife is about to have their 2nd child any day now.    

It comes complete with an oil leak or two, carbs and cables that need adjusting & synch, and a speedo that really needs help (like many BMWs, the odometer still works perfectly) and an exhaust leak at one of the header-to-muffler joints (Aftermarket mufflers), but my fingers are crossed that there won't be any big unpleasant surprises..
Oh, and after checking the VIN the bike was built in November 1977, making it a 1978 model, not a 1979 as advertised and registered, but I am assuming that it was sold as a holdover and got registered as a 79.  Numbers match, too.

{Edit: Front tire is Bridgestone Trailwing 100/90x19 (same as on V-strom), rear tire is Pirelli Scorpion A/T.    Definitely more like tires you'd expect to see on a GS airhead than a "street" airhead.  Maybe they are good on dirt roads and/or bikes designed for them but from my 4 mile sample ride on pavement they are NOT very confidence inspiring, leastwise on this bike's geometry - I'm gonna check the steering head bearings soon - things seem suitably "snug" with 0 play, etc., but there is no BMW std steering damper on this bike and it seems a little TOO easy to turn the bars from side to side/will readily flop over with no effort}  

[DanielMc]

My first BMW was a '78 100/7 and I wish I still had it. The soft tune motor should be good for sidecar work, but you might want to fit another front disk as the single disk ATE brakes were marginal at best. You won't easily find an under-tank master cylinder of the correct size, but a later handlebar mounted 14mm would work and improve things even more. The steering damper was optional on these bikes and should be an easy retro-fit provided you have the necessary threaded holes in the lower clamp - they usually do, but I have seen them without. Correct steering head bearing adjustment is pretty critical on airheads of this vintage, and I've seen more handling problems caused by them being over-tight than loose. When correctly adjusted, and with the bike level on the centrestand, there should be zero play but the bars should fall easily to either side (from straight ahead) with the slightest push.

As per other thread - these bikes go nicely with BT45s! Good news is that they're available in the "old" imperial sizes of 3.25 19 and 4.00 18.

[suecanada]

Congratuations Mike!!!! Now you have a winter project! Hope this doesn't invade upon Laura's list

So now you will be able to go anywhere and never worry about falling over or melting into the pavement on hot days! And just think of the tent size you can take. You will need weight in that sidecar right??!! And all the stuff you can buy at the rallies!!!! And, and...winter riding??? And, and, and....me as a passenger around a country block to the BBQ!!!!

[SCJJR65]

I'd say you gotcha a pretty good candidate for a hack, Mike!   [smiley=thumbsup.gif]

Looking forward to seeing it mated up with your sidecar!

[Justin B.]

Have fun on your project!

You may be OK on the valves.  I seem to remember reading that the problems happened AFTER the factory switched to the unleaded valves in '80 or '81.

[nhmaf]

I've got my fingers crossed, but haven't checked the valves yet - though I HAVE already checked the exhaust header nuts and exhaust port threads (they are PRISTINE !!!!)   I am hoping further happiness awaits me.

I agree that the old "swinging" ATE caliper design with undertank m/c is a much inferior design.   I hate that there is none-to-little real feedback at the lever with the cabled activated m/c versus the handlebar mounted design.   If I manage to score a dual disc front end, either a right leg with proper ATE setup or perhaps even an later model full fork setup with Brembos I may try hook it up with a later model rectangular m/c...   Well, I'll add that to the list of things to investigate eventually..

[msbuck]

Congrats Mike!  Sounds like quite a project you have ahead of you there.  Lots of fun tinkering in your future.  Looking forward to seeing it make progress.