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1985 r100rs

TEDZEMLICKA

Member
I've had a K bike, 3 oilheads, and 3 camheads, so it time for an airhead. I'm going to look at a 1985 R100RS at a local auction. 49,000 miles with a dead battery. It seems they would want it to run to boost bids.
What can I check with it not running? My current plan is:
Cables
Tires
Brakes and fluid
Play in the rear wheel
Look in the fuel tank for rust, crud, etc
Remove the saddle and check that area
Look for any bad wiring

The estate is also selling a couple Harleys and a dirt bike, so they were a rider.
 
I'm not sure of the cutoff, but there weren't a lot of 1985 R100RS twin shock models as they were phasing them out. According to one of the websites, there were R100RS models build in late 1984 which qualify as being 1985s. The mono shock seems to be dated beginning the summer of 1986.

Do you know if you'll get any maintenance history? Maybe look for signs of weeping oil around the cylinder bases. You'll probably have to consider a basic mechanical restoration in order to get the bike up to running status.
 
Your response triggered a closer review of the listing, it's a 1984.
If I'm the winning bidder it can be an off season project.
 
Dead battery?

Huge red flag on buying a bike that does run due to dead battery. Will they allow you to bring a fully charged auto battery and jump start it. Even if it won't start you could test the starter spinning, proper lights on the instruments etc.

Or maybe the asking price is SUPER low?
 
I've had a K bike, 3 oilheads, and 3 camheads, so it time for an airhead. I'm going to look at a 1985 R100RS at a local auction. 49,000 miles with a dead battery. It seems they would want it to run to boost bids.
What can I check with it not running? My current plan is:
Cables
Tires
Brakes and fluid
Play in the rear wheel
Look in the fuel tank for rust, crud, etc
Remove the saddle and check that area
Look for any bad wiring

The estate is also selling a couple Harleys and a dirt bike, so they were a rider.

1984? See if you can pull the valve covers and take a look at the valve adjustment screws. They should be about the same length exposed on the outward side. If the exhaust valve is significantly longer, you're going to be in for a valve job to the tune of $800ish dollars. The exhaust valve, as it becomes more tulip shaped, moves the valve stem outward.

I have an 84 R100 and had an 83 R100 and both years are subject to valve recession issues. At 49K, if they haven't been done, they're on their way and are due by now. 44K on the 83 and they needed it, 38K on the 84 and they needed it.

Of course, while you're in there, you'll want to do pushrod tubes and seals, and clean the carbs and do all the things, so maybe allocate a couple hundred bucks more for parts and bits to make it perfect. It's a good time to upgrade to bigger valves, especially on the RS.

I did that on both bikes and the roll on at 4K was really, really strong up to about 5500rpm. It's a smidge more than just going stock, but man, it really wakes the motor up.
 
For an '84, it will be more than just the valve seats. The actual problem is that the seats BMW used don't transfer heat back into the heads and therefore the valves themselves, especially the faces of the valve, take the brunt and begin to tulip. The only solution is to replace with post '85 components.
 
Depends

Buying a used bike is a gamble anytime. In this case, a non running bike, a red flag. How was it stored when it was not running? I have seen improperly stored bikes turn into door stops or thousand dollar money pits for the second owners.

Lots of things to consider here. I give the same advice to all potential buyers, just because it is a BMW does not make it worth a lot of money, so, the selling or buying price has to be the major consideration depending upon condition. it is VERY easy to buy a BMW bike and end up spending a lot of money to fix problems that are hidden (we don't have X-ray eyes), or caused by improper storage, lack of maintenance, or just plain stupidity of the previous owner.

I have been talking texting a fellow who just bought a RS and found it was not as nice as he was led to believe. Buyer Beware. St.
 
For an '84, it will be more than just the valve seats. The actual problem is that the seats BMW used don't transfer heat back into the heads and therefore the valves themselves, especially the faces of the valve, take the brunt and begin to tulip. The only solution is to replace with post '85 components.

Yep. It's all gotta come out and get machined.

It's a consistent issue with those bikes. FWIW, it took about a month for Ted Porter to do mine and send them back, so it's that time of year. If you check his web site, you can see what the current turnaround is.
 
Ted Porter ... current turnaround is.
infinite, AFAIK

Beemershop no longer does head work. Evidently wants to be mail order suspension guru mainly
he doesnt even allow walk-in these days; to do a pick up, you have to buy online & call from outside and wait on the stoop for a package of goodies .
The current experience feels like a weed deal from back before my bike was born ¯\_ (ツ)_/¯
 
infinite, AFAIK

Beemershop no longer does head work. Evidently wants to be mail order suspension guru mainly
he doesnt even allow walk-in these days; to do a pick up, you have to buy online & call from outside and wait on the stoop for a package of goodies .
The current experience feels like a weed deal from back before my bike was born ¯\_ (ツ)_/¯

Well, that sucks. I just got mine done a couple months ago.

I guess at that point I'd go with Bob's or Max.
 
infinite, AFAIK

Beemershop no longer does head work. Evidently wants to be mail order suspension guru mainly
he doesnt even allow walk-in these days; to do a pick up, you have to buy online & call from outside and wait on the stoop for a package of goodies .
The current experience feels like a weed deal from back before my bike was born ¯\_ (ツ)_/¯

All good things come to an end at some point. Bummer though.
 
Is there a "golden era" of airheads I should steer toward?

That's a can of worms! It's all a personal choice. People like the sedateness of the R75/6 or R90/6. The '77 R100/7 has the last engine before EPA standards kicked in. People like the clutch carrier flywheel which got rid of the heavy flywheel. Electronic ignition started in 1981. Monoshocks started in 1985. There's a paralever rear suspension as well. On the downside, the '85-95ish transmission had a circlip removed which possibly contributes to bearing movement.

So, just find something that speaks to you and go from there! Good luck!
 
I've had a K bike, 3 oilheads, and 3 camheads, so it time for an airhead. I'm going to look at a 1985 R100RS at a local auction. 49,000 miles with a dead battery. It seems they would want it to run to boost bids.
What can I check with it not running? My current plan is:
Cables
Tires
Brakes and fluid
Play in the rear wheel
Look in the fuel tank for rust, crud, etc
Remove the saddle and check that area
Look for any bad wiring

The estate is also selling a couple Harleys and a dirt bike, so they were a rider.


read the plugs. Bring small tools , they look less threatening.
if the vibe is right, dont ask.

Turn it over with the back wheel in high gear w/ plugs pulled.
rotate fore & back wards, & play guess-what-clunked . A Mechanic's Steth-o-scope helps.
just go slowly and be sensitive ......................... its a frickin wake, for gosh sakes ...




bring a flashlight to peer in the holes to scope the piston crowns & better yet the valve lips.
I look weird in public with a flashlight / magnifying headset ,but they get the job done.

they didnt crank it over, cos they dont know how , or just dont care about the Dearly Departed barn child.
so bring a battery & try crank it over, Dr. Frankenstein

Your own-battery shows commitment . To an asylum, according to that bike list above , seeing as you're still shopping around.
Sometimes I have to remind the ol'lady what a remarkable estate sale she can have, too, if only I get just this one more

wiring is always cheap & easy. til its not

YES flashlight the tank interior (or, use a lighter to look in there & pick it up , after parole, at the fire insurance auction , really c'heaped.
I dropped $500 saving the paint on a failed-liner tank , at GTL , Worth every smile-per-gallon (good job guys !) , but still ...

hover non-descriptly but territorially ( not showering that morning always helped me RE: establishing elbow room while bidding ...)
and mutter , to no one in particular, "man that harley sure is a sweet deal" every time somebody oggles the RS

Keep perspective; If this match was meant to be , great! I wish the two of you 2-valve double happiness !
If not,
chase it down and pass it like, real bad , on the K

naturally tell us what it costed, and post pix or it didnt happen

bmw rs - 1.jpeg
?
 
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It's an online auction and the chance to see it was today.
They wouldn't let me pull a spark plug and the battery is dead. Took a flashlight and this is what I found:
Opened the throttle and released it, about 4 seconds for it to close.
The fuel tank was dry. No evidence of sludge or rust.
On the center stand, it shifts through all of the gears.
I could turn the rear wheel over by hand in 5th gear but not in 1st. Could feel the compression stroke.
Is the side stand supposed to be almost impossible to use?
Exhaust pipes aren't carboned up.
Oil was clean.
Oil on the bottom of the sump, dry everywhere else.
Driveshaft boot was dry.
Front brake master cylinder reservoir was dry.
The key didn't work in the ignition, fuel cap, or fork lock. It did rotate 90 degrees in the seat lock.
I'm 6'2", so a bit of a monkey humping a football syndrome on this bike.
I'll keep disciplined in my bidding.
It green, with a green and yellow roundel? Kind of neat.
 
It's an online auction and the chance to see it was today.
They wouldn't let me pull a spark plug and the battery is dead. Bummer but normies are funny that way


Opened the throttle and released it, about 4 seconds for it to close. . The bing IS a CV, bellows topped carb, dampened action.

The fuel tank was dry. No evidence of sludge or rust. Nice. Very nice


I could turn the rear wheel over by hand in 5th gear but not in 1st. Could feel the compression stroke. As normal as the test allows. Turing engine in lower gears is supposed to be a PITA, more compression/power strokes per wheel revolution. Makes sense when you think it out


Is the side stand supposed to be almost impossible to use? Yes. aber , wir bei bmw denken das... ..... The fail-safe side-stand is AKA crash bars, or aftermarket

Exhaust pipes aren't carboned up. Nothing like stickin a finger up it to mark territory, still I am troubled by the monkey reference below

Oil was clean. Oil on the bottom of the sump, dry everywhere else. Driveshaft boot was dry. All in good time. Not particularly leakers

Front brake master cylinder reservoir was dry. Kits are cheap, deeper reapir possible. Dry may be better than rotty grotty fluid in it

The key didn't work in the ignition, fuel cap, or fork lock. It did rotate 90 degrees in the seat lock. Not good, maybe spendy to bring all to single key, but a clanking key chain makes the man. There are hacks to make most of the locks work with less tumblers, if you really want to go simple

I'm 6'2", so a bit of a monkey humping a football syndrome on this bike. HUH? IMO these are decently big bikes , if without a ideal place for hiway pegs. Maybe it was lowered for a orangutan rocking rear sets. Bar risers do a lot. Im 6'4 and always have to stretch a street bike to fit.

I'll keep disciplined in my bidding.
It green, with a green and yellow roundel? Kind of neat. previous owner probably shopped Etsy a lot.
 
Rs

The R100RS bikes were BMW's lowest handle bar equipped bikes at the time. I am also 6'2" and 300lbs. I have mine and love it except I am getting older, and the low down head up riding position can sometimes cause a sore neck. K75S bars have been known to be installed to improve things. Really at speed the problem is not so bad, it is when in town traffic going slow and there is less wind pressure on the head and shoulders to help.

The only other complaint I have about the low narrow bars is the bike can be a royal bitch to move around when off the bike like in my garage putting it on the lift or on and off the center stand, moving it from place to place. Not bad when in the saddle both feet paddling standing on the side, another is another story.

OKAY, you have a bike for sale, you can't start and test ride, not a problem if you get it for the RIGHT price, and if you need to do a lot of work, you can do the work your self. Don't let people blow sunshine your way, it can get very expensive to get a bike running while I have not been burned personally, I have seen more than a dozen fellows the past two years get rapidly drained of wallet when they bought bikes and found hidden surprises.

LOL, is is very easy to write and say go for it! When I am not the one who will be paying for it. Maybe I am weird but I HATE seeing people buy airheads and get burned, it ruins what could be a great experience of motorcycling. Not to say you will be burned... St.
 
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