1978 BMW R100/7 - Airhead project

andrew6v

Active Member
Hi all,


I'm a on-again/off-again creeper of the forum, and thought I'd throw up a post for the Beamer I got over the weekend. I have a Suzuki SV650 as my daily driver and wanted something to tinker on over the summer (I'm an accountant, so I have no spare time over the winter), and I always loved the look of the old airheads.

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Unfortunately that photo was taken yesterday, and there is still a sad amount of snow on the ground.

We drove a couple hours to pick it up, ended up picking it up from a guy in the valley whose toys are probably worth twice as much as his house. He had about 7 motorcycles (Victorys, Harleys, and a new BMW), this BMW, and apparently two Norton Commandos in boxes. He was a Mechanics professor at the local college, and used to own 14 motorcycles, including 7(!) Norton Commandos. I was able to pick it up from him for $2300, which is probably about half what I've seen for similar BMWs (in good working order) go for in my area. He also liked me so he threw in a new progressive suspension set he meant to put on but never got to it. Apparently I'm the third owner, he had it for 15 years, and the previous owner bought it new in Germany while he was stationed there and brought it to Canada. I'm inclined to believe the Germany story anyways, as the Tach has "UPM" and something like "Fernicht" (can't remember exactly) on it with no English.

It's in pretty good shape, no rust or anything (which is hard to pull off in Nova Scotia), but has been sitting for about 10 years so it needs some maintenance to get it roadworthy again.

It has trouble starting, so I'm going to flush out the old gas, and replace the brushes in the starter, and check out the points system. I'm going to see about upgrading to an electrical ignition. The bike actually runs well, but I've only been able to start it when it's connected to a truck battery cause it will kill the motorcycle battery before it fires up. The battery is brand new, so I doubt that's an issue.

Fortunately my Dad is a retired electrical technician who used to service the Navy ships, so motorcycle electronics, no matter how complex, are still not a big deal compared to the couple thousand miles of wiring and all the sensory/communcations equipment in a submarine.

The front brake is seized, so I'll have to fix that as well, and I'm just going to go through the Haynes manual I got with it and replace the fluids, and do the other suggested maintenance.

I hear the tanks can rust out easy too, so I'm going to look into lining the tank, any suggestions?

My current plan is just to get it roadworthy. In the future I'll probably remove a bunch of weight off it (without cutting anything) and look into building a new seat. For the moment I'd like to keep it two-up, but maybe in the future have two different seats, or some sort of convertible cafe hump.

I'd also like to replace the front end with a more modern suspension, but I'd like to try and keep the vintage look, probably by keeping fork gaiters on the new suspension, and similar fork ears.

Does anyone know anyone based in Canada that caters to these motorcycles or is it just the various BMW dealers? The closest dealer to me is in another province, so If I need anything (besides very basic items) I'm probably going to have to ship it anyways.

There are a couple shops in California and Florida that focus on the airhead bikes, but I haven't been able to find one in Canada. That USD/CAD exchange rate is brutal right now, so I'm less keen on ordering stuff from the states.



Andrew
 
Welcome, I was just in your neck of the woods to see the Hip. There were bikes out and it was funny watching them ride between the 4' snow banks. Nice score on the bike and there are quite a few German cars and bikes in the area brought home by folks who bought them while stationed in Lars before they closed.
 
Yeah there are definitely a number of old BMWs here, cars anyway, my buddy owns an ~1988 m3 that's also a German market BMW.

Today I got the bike outside as the weather was pretty nice. My Dad's garage is currently pretty packed to work on stuff, with his Volusia, my SV650, and the MGB, not to mention a ton of junk. I took off the bags and the windshield, which makes a big improvement in the looks department, but it's nice to know they can be easily put back on if I go for a haul when it's more reliable.

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Since it isn't starting great I checked the brushes, they say that 8mm or less is shot, but the brushes on mine were about 12mm so not bad. I think the starter should probably just be replaced with something more new and improved, as it struggles.

This bike is a pleasure to work on compared to the SV650 or VT500 ascot I had. Everything is pretty simple, and easily accessible. The points, and electrical system is all at the front of the engine, and super easily accessible per below.

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So far I'm pretty pumped about the purchase ;D
 
That last image doesn't seem to show up for me, probably because they are both quite large images. I attached it below.

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The brushes are the same as the two white boxes on top of the rotor.
 
I think I'll look into the carbs next, there is a guy that runs a BMW shop, Chris Harris, that has great videos on youtube, that go through a lot of general repairs/adjustments that need to be done to these airheads, some of which I already need to do. I stumbled upon one regarding a certain issue that has been known to cause hardstarting, so hopefully that will work out.


https://www.youtube.com/watch?v=Wpd27HTGCv8
 
Beemers are a bitch to start if the valves have closed up. Torque the head properly then set the valves. Make sure the timing is ok and it should start. Then dial in the timing with a light at full advance. Always disconnect the battery negative when taking off/on the front cover....you can fry the diode board.
 
I have a hondaman ignition for that bike if you get the itch to make the points last longer.
 
Hmmm good to know, I'm planning on resetting the valves, but I was thinking I'd replace the pushrod seals at the same time, and I've just been trying to source a good BMW parts dealer in Canada, with the USD being strong, everything from the US comes with a 25% premium.

Unfortunately the closest dealer to me is in another province, and when I asked them for the cost of the gaskets, and seals they didn't even respond.

Yeah I always disconnect the battery when I'm dealing with the electronics. I'm no whiz, but I know enough to cut out the source when you are fiddling with the electrics.

I may take you up on the ignition, once I save up some more money. I didn't plan on buying another motorcycle for a while and it definitely set me back haha
 
Andrew, try calling Aadrian's cycle in Moncton, they were a BMW dealer and can source most old parts better than the Douchbags at Atlantic Motoplex who didn't respond. They may even ship you the parts but if not it might be worth the drive to get them. I forget the parts lady's name but she has put more than 800,000 km on one of her BMW's.

Cheers

Maritime
 
BMW parts are generally 1/2 the price in the US than in Canada. I've made many trips to BMW in Rochester NY to pick up parts (made worthwhile because there were 2 of us working on our old R75 and R90's).

The starters on these bikes are massive beasts - if yours is struggling, check the battery and make sure you keep it on a charger. Until it's running repeated attempts to fire it up will drain it very quickly.

Your tank should be fine rust-wise. BMW lined them at the factory with ironically a rust-colored coating. Run inline fuel filters if you're concerned, and make sure your petcocks are free flowing.

Don't spend any real money on your Bing CV carbs. For the price of new diaphragms you can replace them with Mikuni VM carbs. I run VM32's on my R75/6. A bit of work to get it all sorted, but I run those carbs on all my bikes so having common jets etc. across them all is nice.
 
Good points all around, I appreciate it.

I'll try Aadrians, and at least get a somewhat local price point to compare to.

I saw that it killed the battery very quickly, and the battery is brand new. Good to know about the tank, the PO has inline fuel filters on it, so no issue there.

I'll admit I was a little surprised to find out that a full rebuild kit for both bing carbs was like ~$200 USD plus shipping, which seemed a little outrageous.


Andrew
 
Also there are lots of places in maine at the border crossings you can have parts shipped to for a small fee then go get them. I do that all the time being only 15 mins from the border but plenty of folks farther away do it, when you are looking at a lot of little parts they can add up to make the gas and time worth it, even at 25% exchange
 
I only paid 70 for the electronic points ignition. ...so cheaper to you when ready...I put a full electronic on mine. I would get it running first before tearing down for the push rods seals etc.
 
My guy for the big stuff said you can tap the push rod tubs down to tighten temporarily. Plus he said if it runs strong no need to go monkeying around doing rings and such. I swear doing a torque on both heads and setting the valves made mine like a new bike. They had closed up so bad it was a real pita to start and very boggy on the acceleration. Surprised it would even run....tough bikes. www.motoelekt.com for anything electronic, he's the best I have found.
 
Managed to get a new starter as the old one was pretty weak, even after adjusting the valves and re-torquing the head. Unfortunately one of studs in the valve cover and the related threads in the head got stripped so I'll have to deal with that. Fortunately it's not one of the bolts that goes all the way into the block, just the valve cover, so no big job just to get at it.

To get to the starter I had to take the top of the engine off, I still have to say it's nice working on this bike, everything is fairly accessible/simple.

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Out with the old

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In with the new, the image is from the opposite side of the bike.

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While I was in there I checked out the brake master cylinder and the filter. Based on the corrosion, I'd say the master cylinder leaked out a while back, so that needs to be rebuilt, and the air filter is shot as well. Oh well at least I know that both will be good to go for a couple years once they are replaced.

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I didn't get a chance to fire it up, as I figured I'd leave it disassembled as I plan to clean and grease the splines in the transmission which involves the same amount of dis-assembly plus opening up the transmission. Apparently it's a required and obviously important maintenance item which should be done every 12-30,000 miles. Hopefully it was done at least once before I owned it.

http://www.airheads.org/technical-tips-articlesmenu-98/198-lubing-transmissionclutch-splines-rev-09212007

That's the article by Robert (Snowbum) Fleischer who has written a lot of good technical articles about all the details of these motorcycles. It's good information but I find it hard to read as it's not overly user friendly, not so much due to the technical nature, just that his articles are a bit more like rants hahah

Anyways that's it for now, I'm hoping to get it roadworthy by end of July as the insurance on my other motorcycle runs out early August, so I can just run one bike at a time. The Suzuki needs some work done as well, so it's a good time to only have one on the road.



Andrew
 
Been a long while since I updated anything, unfortunately last summer I got a pretty late notice that I'd be working in Newfoundland for most of the summer, so the bike sat at my parent's place with nothing done on it.

Also unfortunately it was the coldest July Newfoundland has ever had on record. Pretty sad that on July 15th I was running from the hotel to the car to blast the heaters......

Anyways I rebuilt the carburetors, with fresh seals, diaphragm (the old ones were mangled), floats, float needle and slide needle, as based on the Airhead beemer club tech section they should be replaced at around 100k km which the bike has 92.

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Disassembled

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Cleaned before and after. I actually boiled them in lemon juice, really took care of the cleaning, and I planned to replace all rubber elements so I figured it would be fine. Smells rank though, and makes a nasty pot to clean-up, so I'd recommend not using the good pots haha

I also realized that there was a hole in the float bowl... so I ordered up a new one.

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and of course I mixed up right and left... ::) oh well ordered up another, and now they look a little more bling with two brand new float bowls.

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The only seal I was waiting to get out until today was the butterfly valve shaft o-ring, as the screws were a bastard to get out, and I didn't have a small flathead to do the job. It was still a bastard with a jeweler's flathead screwdriver. I put "Knock-er-lose' penetrating oil on them, and then froze the carbs in the freezer, then took a blowtorch to the shaft to heat that up. They came loose but were still a bugger to get out, and one got so mangled I needed to unscrew it the last few threads with vice-grips.

:eek:

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A machinist friend of my father's was over at the house, and the heads were partially disassembled he noticed that the cylinder's were glazed and needed to be honed.

We needed to take it all off to replace the pushrod seals, but then now it became a piston ring replace job as my dad gave it to him as he'd hone them for free.

That Snowbum guy has a lot of good detail on his website below, (a bit rambly though) and a new Clymers was helpful. I got the bike with an old Haynes manual and it frigging useless compared to the Clymers. The Haynes manual is literally a 4th the size of the Clymers.

http://bmwmotorcycletech.info/break-in.htm

So we got the heads all disassembled. Talk about weight-loss.

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Cleaned off most of the carbon so we could see the BMW stamp as to which way the piston goes back in + new rings.

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New seals in place, this is one of the older airheads, which unusually doesn't have a large o-ring at the base of the cylinder where it meets the block (basically any from 1979 on had it). That said it still requires a sealant so we threw that on after this pic was taken. The piston is in there with the new rings on.

Then we threw them back in.

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The whole disassembly/new rings/seals probably took a few hours. However this is this circlip that locks the piston on to the gudgeon pin or whatever it's called that connects it to the rod. It was a pain just to get out, getting back in to that little groove was a whole nother story.

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It's pretty strong steel, and will flex, but you can't do it with your hands. So that took another 3 hours to get in :mad:

Friggan poor design, I guess the later ones have to metal circles on the ends so you can throw it in with snap pliers in like two seconds... I seriously considered ordering those up, but I haven't heard about their interchangeability anywhere.

Other than that I got the valves ground, and heads carbon removed.

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Glad I got those ground, the exhaust valves were leaking pretty badly when I put gasoline in the exhaust port and held them up. Took a good while, and many times of putting the springs back on and checking, but everything doesn't leak anymore ;D
 
I realized I could have walnut blasted or similar the cylinder heads, but I just want to get it on the road to blast around this summer, and we'll see about giving it a makeover later haha particularly where yesterday was the first real warm day of the year, I'm itching to get out.

Here it is as it sits now, the wood clamp is to adjust rocker end-play which is now done, and the valves are adjusted. The rockers are supposed to be able to move (almost imperceptibly) but if you can hear metal on metal clink, it's way too loose.

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And then I got the goods for this week's project, brakes. I have the rebuild kit for the ATE master cylinder, o-rings and rebuild kit for the caliper, and SS lines and Ferodo platinum pads. I realize that alot of people consider the brakes lacklustre on this bike, however others that have fully rebuilt the master cylinder and caliper with good new pads find it's adequate. One BMW dealer/racer actually has this same set-up as mine on his race bike and finds it more than fine. However his bike is pretty trick otherwise, and I imagine has quite the weight reduction. Long story short, the price is right on this route for myself.

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I also have a new condenser, points, spare ignition coil, and my Dad will be helping me out with that, may as well make use of 35 years experience as an electrical technician (and free labour hahaha ;D). Again it's a price is right, and quick to do. I probably upgrade to a digital ignition someday if I'm still rocking the bike in a couple years.

That's about it for now.
 
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