New to me, BMW airhead

[sdcr]

It followed me home...

So a friend of a friend told me about a 1983 R100 that has been languishing in a neighborhood garage for several years. Owner parked it, battery went flat and that’s how he left it. Still has the same gas in the tank, which smells like gas. Brakes function, bike rolls, and the engine is not stuck. Clutch lever operates.
 
The good;  Everything is there, and engine is free. Has the sexy BMW cafe fairing. Gas tank is still that reddish primer, don’t see any rust. Body work is very straight except, more on that coming up. Has two side stands, one oem, and another very long one, Brown maybe? Tool kit, spare tube, even has that long cable lock, but it stuck in the frame. 47,000 miles. Owner gave me a large box of new spares, BMW oil, filters, fuel treatment And one Bing rebuild kit. I like the greenish, blackish color. Has a pair of BMW aside cases. Bike is eligible for a classic tag, no registration fees after initial app.
 
The bad; Fairing  has a small scuff, about the size of a quarter. Tires are new lasers, but six years old. Dead battery. Mufflers are solid, but have a some pitting in the chrome.Bought it without hearing it run, as is.
 
So, being not the most mechanically savvy, any suggestions on what to do first, second etc are very much appreciated.
I am hoping to get this on the road this spring.

[czakky82]

Re-torque heads, check valves, set timing, push rod seals? Generator brushes? Do those still have the funky oil filter?

The Bing CV carbs are bulletproof.

[PeteS]

Change the gas and oil, put in a battery and see if runs. These have electronic ignition which is not going to change by itself.
Did you know if any valve work was done? These came with the infamous too hard valve seats that melt the valves in short order. If they have been done you should have an idea when it idles. Idles OK you should be OK. Idles rough you need to look into it. If the fix has not been done I don’t know who does the work nowadays. Back in the day it was San Jose BMW or Randy Long in PA. Not sure if either are around anymore but the airhead club would know.

Pete

[RinkRat II]

     A great,funky and entertaining site for all that is Airheads https://bmwmotorcycletech.info/

      Paul B 

[sdcr]

Thanks guys, definitely changing the carb diaphragms. Yes, does have the hinges filter. Not sure about generator brushes, but the push rod seals appear to be dry.

First thing is to get a battery. It’s the 30L size  Wow, prices are all over the place. Low of $41 at wall a tort to $200+. Any recommendations on where/ what battery ?

[sdcr]

Thanks Paul, I’ll check it out. I posted here because you guys know your stuff

     A great,funky and entertaining site for all that is Airheads https://bmwmotorcycletech.info/

      Paul B 

[Antietam Classic Cycle]

I'd rebuild the carbs entirely, including new diaphragms. Fresh gas and oil.

Battery: made in PA, East Penn Mfg./Deka: https://www.batterymart.com/p-Big-Crank-ETX30L-Battery.html

[sdcr]

Charlie,

Do you have good experience with the BigCrank batteries? That looks like a decent price.

I don’t mind spending $120-$160 for a sealed battery. NAPA has a correct size 30L for $159.

[Antietam Classic Cycle]

Charlie,

Do you have good experience with the BigCrank batteries? That looks like a decent price.

I don’t mind spending $120-$160 for a sealed battery. NAPA has a correct size 30L for $159.

Yes, average life span is 7 years. Big Crank is Deka with a different sticker.

[PeteS]

Charlie,

Do you have good experience with the BigCrank batteries? That looks like a decent price.

I don’t mind spending $120-$160 for a sealed battery. NAPA has a correct size 30L for $159.

Most all Napa batteries are made in the US including their NAPA Legend brand batteries.

Pete

[Navydad]

These folks are just outside of Columbus, Ohio and when it comes to BMW's they are one of the best. Questions or parts, this is your go to place.
https://re-psycle.com/

[Antietam Classic Cycle]

The 1st Deka battery I bought for my Eldorado failed in a few weeks. Its replacement failed in a week. Third one was a charm. Nothing against Deka and have used the since as long as there is a bricks and mortar store to return them if there is a failure

Never had one fail in the 10 years I've been buying them. Probably 30+ purchased for my own and customer bikes. 90% of those were "Marathon" or "Big Crank" branded and purchased from Battery Mart (in Winchester, VA and Martinsburg, WV) though.

[JJ]

This is a tasty "Toaster-Tank" airhead right here!! 

https://bringatrailer.com/listing/1973-bmw-r75-5-7/

[Motormike]

What model R100?  Can't quite make it out in the photo.

[Scout63]

That is a great great looking bike SDCR.  I rode the same year and model with the same fairing and bags cross country.   Give it a few thousand miles to sink into you. I’d also pull and replace the fuel lines.  The cloth covered bmw lines tend to crack and leak. Please post many pictures.

[PeteS]

What model R100?  Can't quite make it out in the photo.

Its the base model. R100 or R100T. No fairings.

Pete

[SoCV]

Its the base model. R100 or R100T. No fairings.

Pete

 Isn't that an "S" fairing ?

 Dusty

[cookiemech]

I see bag mounts, so likely an R100T (those had no fairing whatever, but did have bags). Lot of people installed the "S" fairing as an accessory. (I have a 1982 R100T; excellent long-legged machine.)

For OEM type parts, I recommend Euro Motoelectrics. They source parts from the original manufacturers and thus sell a lot of them significantly cheaper than does BMW. Always quick shipping, in my experience.

https://www.euromotoelectrics.com/Default.asp

[sdcr]

Mike, apparently it’s a R100. No other designation. I’m not sure if the fairing was installed as an aftermarket. With the fairing, the bike resembles the R100 CS.

Here are a couple of pics this morning. Apologies for the dark garage.

What model R100?  Can't quite make it out in the photo.

[usedtobefast]

Me being a thrifty type ... I would use a battery from some other moto I owned to ensure it runs OK before spending $170 ish on a really nice new battery. 

Another thing I didn't see mentioned ... air filter?  To make sure there wasn't a mouse nest / trash in there. 

Sounds like a fun bike and a little bit of a "bring it back to life" project. 

[sdcr]

Thanks, points taken. I was able to rotate the rear wheel in gear, to see that the motor is free. The flat battery took a charge enough to get the starter to spin the motor. I’m ok with getting a good battery, just ordered a Big Crank ( thanks Charlie ). Nothing seems to be really whacked, and even if I need to do the carbs, I’m ok with it.

I think its a sweet machine, and it’s been a few decades since I’ve had an airhead BMW. Last one was an 86 R80 RT. Looking forward to the rapid speed this R100 will produce, compared to the R80. 

Me being a thrifty type ... I would use a battery from some other moto I owned to ensure it runs OK before spending $170 ish on a really nice new battery. 

Another thing I didn't see mentioned ... air filter?  To make sure there wasn't a mouse nest / trash in there. 

Sounds like a fun bike and a little bit of a "bring it back to life" project.

[cookiemech]

I had a 1986 R80RT. What a total pig . . . not much power, sucked gas like there was no tomorrow (33 mpg in the dead of winter; high 30s in summer). It's a wonder I ever bought another BMW (I've had six more since then).

The 81 to 84 R100s are way better. They don't have the choked-down "stylish" mufflers of the Monolever bikes. They are rated at 66.5 hp (of course, those are German horses) vs. 50 for the Monolever R80.

But the R100 is also geared taller, so you need to be running 65 or 70 to really use fifth gear. A nice-running R100 is sweet on the open road.

[sdcr]

One interesting thing about this R100 is the snowflake style wheels. At some at some point, probably many years ago, one of its owners had both wheels powder coated in a “ gold” color. I haven’t had a chance to wash them up, but hope that they do clean up well. Right now they have a clay colored appearance.

[ohiorider]

Change the gas and oil, put in a battery and see if runs. These have electronic ignition which is not going to change by itself.
Did you know if any valve work was done? These came with the infamous too hard valve seats that melt the valves in short order. If they have been done you should have an idea when it idles. Idles OK you should be OK. Idles rough you need to look into it. If the fix has not been done I don’t know who does the work nowadays. Back in the day it was San Jose BMW or Randy Long in PA. Not sure if either are around anymore but the airhead club would know.

Pete

The OP might want to check Ted Porters Beemer Shop for info on updating the valve train if required. Ted has a lot of good info on other topics as well, including suspension work.  He's always been willing to spend some phone time with me.  Here's a brief discussion on bad head work.

https://www.youtube.com/watch?v=R1rI3pog1DU

Bob

[gph70]

I had an opportunity like yours but with a K75 BMW. I downloaded the complete maintenance schedule and did everyone of them. Then on to a forum looking for "improvements" and suggestions, performed those (that seemed reasonable). After two weeks a sweet running everyday machine to this day.
I would suggest new tires. Yes, they have been in the dark for 7 years but I have great faith in improving tire technology, like oil. Fresh maintenance, new tires, long sweepers on a summer day....magic.

[PeteS]

I had a 1986 R80RT. What a total pig . . . not much power, sucked gas like there was no tomorrow (33 mpg in the dead of winter; high 30s in summer). It's a wonder I ever bought another BMW (I've had six more since then).

The 81 to 84 R100s are way better. They don't have the choked-down "stylish" mufflers of the Monolever bikes. They are rated at 66.5 hp (of course, those are German horses) vs. 50 for the Monolever R80.

But the R100 is also geared taller, so you need to be running 65 or 70 to really use fifth gear. A nice-running R100 is sweet on the open road.

One year at the Perry Sound Sport Bike rally I rode my ‘83 RT rather than the LeMans and put it on the dyno there run by a many time Iron Butt rider (Peter Hoogeveen). There was another identical ‘83 there that the owner said was stock. His made 49HP mine made ‘62 RWHP. Many mods to mine including Sport cam, dual plugged, 9.5:CR up from like 8.2. Hole saw to the stock muffler baffles.
Early on I took my engine apart to balance the pistons and rods. They were off by nearly 20 grams. Helped the annoying vibe  in the handle bars. Also filled the bars with lead shot.
I found the ethanol gas would soften the diaphrams such that they wouldn't pull evenly and take the carbs out of balance. Changing them out every three years or so helped that a lot.

Also took it to the strip one year after making these mods and turned a 14 flat which was a couple of tenths better than the magazine testers got. First time ever for me even with a non stock bike. Also almost blew up the clutch trying though.

Pete

[Motormike]

If it was an R100 CS?  Do you know what a clean R100 CS goes for these days?!!! (That's why I asked)

[sdcr]

With some internet sleuthing, I discovered that the 1983 R100, it  came in two varieties. One version was outfitted with a touring handle bar, touring bags. The other, which is the one that is the subject of this thread, came with a flatter, and narrower handlebar as well as the S fairing. It certainly looks like a CS, but is just designated as R100.

If it was an R100 CS?  Do you know what a clean R100 CS goes for these days?!!! (That's why I asked)

[Scout63]

With some internet sleuthing, I discovered that the 1983 R100, it  came in two varieties. One version was outfitted with a touring handle bar, touring bags. The other, which is the one that is the subject of this thread, came with a flatter, and narrower handlebar as well as the S fairing. It certainly looks like a CS, but is just designated as R100.

That clears up my old bike.  It was designated as an 83 R100 but has S bars and fairing and bags.  I always wondered.

[fotoguzzi]

I had a R100T it had a different seat and tail section. The seat was the best ever on a BMW.