Boxerworks.com

Greetings all,

I am currently looking to buy a R100/7 with 57,000 miles on it.

Is there anything in particular to check out on it? Gearbox / engine / telling noises etc?

Any help or suggestions welcomed.

Thats not high mileage by any means for these bikes but could be up for:
Gearbox - they often need a rebuild around 60k miles.
Final drive splines- depends on how well its been maintained
Gearbox input shaft spline - again, depends on maintenance
Top end. Valve guides, maybe valves too.
The usual steering head and swing arm bearings.

Its hard to say without history . Big difference if it has been well maintained.

Good luck with it. They are wonderful machines.
Let us know if you buy.
Cheers
Mal

Welcome to the forum alpha. I think you'll like it here.

There are quite a few things to look out for. I'll only be able to remember a few of them.

It is generally accepted that the transmission is the weakest part of the drive line. Duane Ausherman, a long time contributer here on Boxerworks has written a lot about the BMW airhead care and maintenance. Here is a link to his transmission section:

w6rec.com/duane/bmw/trans/index.htm

What would be great is if, before you buy, you talk the owner into changing the transmission oil (you supply the new oil). The reason you want to do this is so you can feel the "fuzz" that has collected on the drain plug magnet. There will be fuzz there. If the fuzz feels smooth and silky, that represents normal wear. If you feel any grit, though, that is a cause for concern.

While you're looking at and feeling the oil look for any signs of water in the oil. This will manifest itself with a bit of a chocolately look. Looking at the transmission you won't be able to imagine how water could get into the oil. It happens, usually in the rain, when water can dribble down the speedometer cable and into the transmission. Or from washing, as happened to me. The speedo cable entrance, by the way, is on the R/H side of the transmission where the battery cable is connected.

The mileage on the bike, though low for a car, isn't low for an airhead. It's not high either. At around 60K miles the clutch disk (and perhaps some related parts) may need replacement. You can regard this as normal as well.

In the drive train there are two splines to be concerned about. The first one is where the clutch disk slides on the nose of the transmission. This spline should be lubricated once in a while. I don't have a so-many-miles figure to cite. This means removing and replacing the transmission. Some people just slide the transmission back and dab in the proper lubricant, but this is generally frowned upon as inadequate.

Have I scared you off yet?

The other driveline spline of concern is at the rear wheel where the hub goes into the final drive. That area is prone to wear with mileage. Both the wheel and final drive splines can be affected. By carefully looking at the teeth you can see the unworn part compared to the worn part. From this you can judge a percent wear. The final drive splines can be redone. The rear wheel splines can be replaced. (I have yet to determine that any of my airhead's splines "need" to be resplined.)

When looking at the bike I would place the bike on its centerstand, in high gear, with the rear wheel elevated above the ground, and rotate the wheel back and forth. What you're looking for is slop in the whole driveline, which includes clutch and rear wheel splines as well as gear clearances and even a driveshaft spline in the final drive. I don't have an "inches-or-rotation" figure to give you. Perhaps somebody here will. When you test ride the bike gently roll the throttle on and off and feel for the slop in the drive train. There will be slop in there, from manufacturing tolerances in nothing else. But if the amount of slop annoys you than that is a concern.

The R100/7 came with an under-the-tank master cylinder for the front brakes and likely still has it. You will want to pull the tank off the bike and look at the master cylinder there on the top frame tube. What you're looking for is evidence of brake fluid leaks around the rear of the master cylinder. This can get pretty ugly. The brake fluid also has a tendency to dribble down on the L/H side into the connector for a small relay called the starter relay. This can be a problem and should be cleaned.

You will want to bounce the forks up and down by holding the front brake and pushing the bike forward and backward. What you're looking for is signs of fork stiction. Essentially, the fork legs need to be parallel. There are remedies which I won't go into here.

You will also want to check out the electrical functions. Does everything work OK including the lights in the instrument cluster? Old wiring can and does go bad.

If you should not be mechanically inclined, you should know that most BMW dealers don't work on old airheads. Simply, their mechanics don't know much about them.

I hope I haven't scared you off. All old motorcycles will have potential problems of various kinds. You will want to feel the owner out. Is he mechanically inclined. Does he seem to know much about how the motorcycle works? If not the motorcycle's maintenance may have been neglected.

That being said, therre's a reason why old airheads have an avid fan base. The rewards are there.

I reckon others will be along to add to my commentary, perhaps even to disagree here and there.


Ken

Is this a 1977 or 1978 model? The 1977 is a desired bike (IMO) because it was prior to the US EPA getting to it and the changes to the timing and power. I still like my 1978, though.

I have over 100K on my /7 tranny...I wouldn't necessarily say 60K was over the hill. It certainly depends on the rider and type of driving...most of mine is long distance. I just did a top end on my R100/7 to cure a number of things...pushrod tube seal leaks, change to unleaded valves/seats, etc. So far the bike feels new with a lot of pep.

The bike will need attention and rebuild every once in a while...plenty of resources and parts available to do that.

Kurt in S.A.

Thanks everyone - that is a great list already, I really appreciate the input!

I've owned various BMW's over the years but have never owned an airhead, now I am hypnotized by them - I just did a 7000km tour and 3 of the new 1200gs bikes failed due to weeping seals and electrical issues, but there was an old airhead in the group that kept chugging and was more fuel efficient than the almost brand new bikes. I grew up with VW's so I don't mind getting my hands dirty, and if you love the vehicle you tend to fix any issues, even the almost impossible (I've been there and back with my old 57!) regardless of logical things like cost and time!

Many thanks again, I'll be posting up a pic soon as I (hopefully) own it.

alpha wrote:...
I grew up with VW's so I don't mind getting my hands dirty, and if you love the vehicle you tend to fix any issues, even the almost impossible (I've been there and back with my old 57!) regardless of logical things like cost and time!

Many thanks again, I'll be posting up a pic soon as I (hopefully) own it.

Welcome, Alpha.
Sounds like you have the right credentials and attitude. Good luck with your new love.

alpha wrote:
Any help or suggestions welcomed.

BUY IT AND RIDE IT LIKE YOU STOLE IT!!

DucatiPete wrote:

alpha wrote:
Any help or suggestions welcomed.

BUY IT AND RIDE IT LIKE YOU STOLE IT!!

Alternatively, steal it and ride it like you bought it.

Alpha, the good news is that even when we have no knowledge, we will make up an answer that sounds like we know what we are talking about. We won't let you down.

Duane Ausherman wrote:Alpha, the good news is that even when we have no knowledge, we will make up an answer that sounds like we know what we are talking about. We won't let you down.

Ha ha - that's what I do at work everyday!

Hopefully I will ride it like I own it soon