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Topic-icon New Guy - Barn Find - R100GS

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2 months 3 weeks ago #4374 by 4runnerbuck
New Guy - Barn Find - R100GS was created by 4runnerbuck
Good Morning All -

I'm a new guy to the forum. I recently had a family member offer me a 1988 R100GS with 5,500 miles for $2,500. The bike had been sitting in a garage for 15+ years until the last month or so. I have always loved these BWW on/off road bikes so this is tempting!

He took it to a BMW dealer and told them to get it running.....they rebuilt the carbs, new fuel lines, and did some brake work. I removed the air cleaner cover and there was a mouse nest in there but other than than I can't see anything majorly wrong. I rode the bike for about 10 miles and it runs strong, brakes well. I've been around motorcycles all of my life but don't know BMW very well. The bike has some cosmetic flaws but could easily be brought back to life. I am very particular, so I see myself doing whatever needs to be done to make this bike super nice mechanically and cosmetically......doesn't have to be a show bike but a really nice daily driver. I don't mind spending some $ to make it nice but I don't want to get in over my head where it doesn't make much sense financially. Please let me know your opinions......tell me to pass, hand him the money, check this or that, etc.

So, my questions are:

Is this a fair price ? What is the bike"really" worth?
What things should I expect to repair/replace with this bike sitting for so long?
Are these airheads easy to work on? I am very mechanically inclined so doing my own work doesn't scare me!
Are these engines generally reliable ?

Thank you in advance for comments, suggestions and Merry Christmas!

Adam

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2 months 3 weeks ago - 2 months 3 weeks ago #4375 by Wobbly
Replied by Wobbly on topic New Guy - Barn Find - R100GS
Congratulations on an exciting find !

• That's an extremely fair price, especially considering the low mileage.
• These bikes age very well. Just keep an eye on the rubber bits (boots, hoses, grips, etc) and replace the tires/tubes. Greases will have oxidized, so new synthetic greases in the swing arm, head post, and wheel bearings is in order (but you can do this work yourself over the next year).
• These bikes are extremely easy to work on, and actually designed for owner maintenance. Regular owner maintenance is how major repairs are kept at bay.
• These are some of the MOST reliable engines ever designed and put in a production motorcycle. Generally speaking, with regular maintenance you can expect 250,000 miles or more.

► The major area of concern (it only becomes a "problem" when it's ignored) has to do with modern fuels and lubricants. Ethanol fuels (which weren't in use in 1988) raise 2 concerns:
1. The valves and valve seats were designed for leaded fuels, so as you run your best available high-test fuels, there will tend to be slightly more valve wear. You'll simply need to check your valve clearances slightly more often than the manual prescribes. As you do you'll learn how fast the parts are wearing and be able to tune your maintenance periods to the bike's needs.
2. Ethanol fuels tend to add a serious point of aggravation if the bike is allowed to sit. When the fuel sits, the ethanol comes out of solution and begins to absorb water. The water aggressively damages the carb parts, making for hard starting, etc, etc. If you simply ride the bike once a week this is not a problem. Otherwise plan on draining ALL the fuel, OR using a fuel system cleaner and stabilizer. IMHO the best cleaner is StarTron, which does not seem to damage the o-rings in the carb.

Since your bike has already had a history of long storage, it would not hurt to add 1 oz of StarTron at every fill-up until the bottle is empty. This as a preventative measure because there is simply no way a mechanic can clean every part of the fuel system. Think of it as very cheap insurance.

► Next, in the intervening years, motor oils in the USA have also changed formulations. Common motor oils you are likely to find at WalMart (API rated SM & SM) were developed for newer cars. You need to find a source for 1988 grades of motor oils (API rated SF & SG). I can recommend 20W50 Valvoline VR1 available at your local auto parts dealer (like Advanced and O'Reliey). There are most certainly others, but my point is you will need to search out these specific oils.


Hope this helps.

Don't hide 'em, Ride 'em !!
#15150
Last edit: 2 months 3 weeks ago by Wobbly.

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2 months 3 weeks ago #4376 by 8166
Replied by 8166 on topic New Guy - Barn Find - R100GS
Welcome to the ABC and this Forum!

I've moved your topic to the Wrenching section, as that is going to be the meat of your question.

You'll find a great number of technical articles pertaining to the R100GS in the Technical Tips section of this web site. You should become familiar with the weaknesses of airheads in general and the R100GS in particular, and they are all laid out for you, along with possible cures, in those pages.

FWIW, I have almost 150,000 miles on my '93 GS, and the engine has been the most reliable component on it.

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 20-21, 2019

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2 months 3 weeks ago #4378 by 632
Replied by 632 on topic New Guy - Barn Find - R100GS
If it brakes well it can't be a 1988 R100GS! lol
Merry Christmas; your gift apparently arrived early.

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2 months 3 weeks ago #4381 by 4runnerbuck
Replied by 4runnerbuck on topic New Guy - Barn Find - R100GS
Wobbly - Thanks for your reply and suggestions. This will be a fun and exciting project.....although I have a lot of irons in the fire so I will have to make time to get this things ready for spring riding. Happy New Year!

Adam

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2 months 3 weeks ago - 2 months 3 weeks ago #4382 by Wobbly
Replied by Wobbly on topic New Guy - Barn Find - R100GS
Opps ! As proof that you don't need to be infallible to be a Moderator here, I've remembered one more important point you most definitely need to look into.....

• You absolutely should, at a minimum, replace all your brake fluids. DOT4 brake fluids have a maximum useful life of 5 years, which is one reason BMW suggests you replace the fluid on an annual basis. Over its lifetime, DOT4 fluids continue to absorb water from the atmosphere, which is exacerbated by bike washing and riding in the rain. Motorcycles don't have the luxury of a protected master cylinder living in a cozy warm place, like automobiles do. So don't try to equate your experience with the 2 vehicles.

If you have an air compressor, you can make this job easier by blowing air though the assembled system, and the air will route out the pockets of old fluid quite efficiently. If you do not have this advantage, but prefer NOT to disassemble, then you can do the same thing over several weeks by doing multiple complete system bleedings.

[Note here that DOT4 will attack ALL painted surfaces, so it is highly recommended that you get in the habit of bathing the bike in hot soapy water after every adventure into the master cylinder, brake hoses, or caliper.]

• If you prefer a more complete inspection, then may I suggest that the Number 1 upgrade you can make to any hydraulic braking system during disassembly is to replace the OEM all-rubber brake hoses with what is nominally called "stainless steel brake hoses". These are Teflon (PTFE) tubing reinforced with stainless steel braid. The outermost sheath, which is only there for aesthetics, can be had in Black (to look like OEM), clear, or many other colors.

You'll want to pursue this course for 2 very meaningful reasons: 1) a very substantial increase in braking efficiency, and 2) insurance against the very high likelihood of OEM brake hose failure. Both of these reasons have a direct bearing on your riding safety.

Of course there are multiple vendors to choose from. Spiegler is a very good manufactured choice, Bob's BMW will build them to order, or you can plumb up your own from standard catalog pieces from suppliers like Fragola .

Hope this helps.

Don't hide 'em, Ride 'em !!
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Last edit: 2 months 3 weeks ago by Wobbly.

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