Buying an airhead...

I'm looking at a 1972 R75/5 to join the other bikes in my shed. The PO is asking $3500 for it. It looks to be in good shape. There's no rot on the tires, the battery is new, he has receipts for the last couple of sevice checks (he doesn't do his own maintenance).

Nothing is leaking from anywhere, it started up from cold after a couple of tries. The only things I noticed were the front forks seemed soft, the tach needle wandered and the oil light flickered when idling, once it got to about 1200rpm this stayed off.

I took it for a short test ride and the steering and gears seemed in order.

Anything I should specifically look for?

I would be a little concerned about the flickering oil light. Generally, with engine at idle, that light should not be on. On the /6-on bikes, people often confuse the oil and charge lamps. I don't believe the /5 has a charge lamp in the speedo unit.

It could be that the oil sending unit is flaky. That's the first thing that should be checked or changed. If that doesn't fix it, then likely there's some sloppiness in the oil pump and rotors which requires a significant teardown.

$3500 seems a high given some of the other numbers floating around here lately. The /5s can be nice putting around bikes. The potential bike sounds in good shape except for the oil pressure question.

In the /5 speedo/tach combination instrument, the red light is charging and the yellow light is oil pressure. If the red light goes out at around 1200 RPM, that is typical. Now then, if it IS the yellow light, that wouldn't be so good. By the way, the /5 and /6 motors have the bullet proof oil filter canister, so that seems un-likely. Just remember, you are looking at a motorcycle that is 38 years old. Issues will crop up.

woodnsteel said:

In the /5 speedo/tach combination instrument, the red light is charging and the yellow light is oil pressure. If the red light goes out at around 1200 RPM, that is typical. Now then, if it IS the yellow light, that wouldn't be so good. By the way, the /5 and /6 motors have the bullet proof oil filter canister, so that seems un-likely. Just remember, you are looking at a motorcycle that is 38 years old. Issues will crop up.

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+1 Easy to confuse the oil/gen lights -- my reaction the first time I rode SWMBO's toaster was red must be oil because it's an "OH CR**!" problem, but that's not the way BMW does it.

Does that mean that this reference is incorrect:

http://www.eecs.umich.edu/~deroo/bike.dir/owners-manual.dir/opinsp.html

This is what I used to see if there was a charge light in the cluster. It didn't list it so I wasn't sure.

However, when I check the Haynes wiring diagram, it does show both a charge light and the oil pressure light in the speedo.

woodnsteel said:

In the /5 speedo/tach combination instrument, the red light is charging and the yellow light is oil pressure. If the red light goes out at around 1200 RPM, that is typical. Now then, if it IS the yellow light, that wouldn't be so good. By the way, the /5 and /6 motors have the bullet proof oil filter canister, so that seems un-likely. Just remember, you are looking at a motorcycle that is 38 years old. Issues will crop up.

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It was indeed the red light. The yellow light (which I assumed was the generator) didn't flicker at all.

Thanks to all for the help.

Originally Posted by woodnsteel View Post
In the /5 speedo/tach combination instrument, the red light is charging and the yellow light is oil pressure. If the red light goes out at around 1200 RPM, that is typical. Now then, if it IS the yellow light, that wouldn't be so good. By the way, the /5 and /6 motors have the bullet proof oil filter canister, so that seems un-likely. Just remember, you are looking at a motorcycle that is 38 years old. Issues will crop up.

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I second the motion. This is what I see when I look down at my /5's speedo.

20774 said:

Does that mean that this reference is incorrect:

http://www.eecs.umich.edu/~deroo/bike.dir/owners-manual.dir/opinsp.html

This is what I used to see if there was a charge light in the cluster. It didn't list it so I wasn't sure.

However, when I check the Haynes wiring diagram, it does show both a charge light and the oil pressure light in the speedo.

Click to expand...

scroll down to Fig 5. it's there, listed correctly.

bikerfish1100 said:

scroll down to Fig 5. it's there, listed correctly.

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That's odd! I stopped looking at the first figure. Oh well... This is obviously someone's own typing but using the figures as needed. I guess they just didn't list the correct elements of the speedo in the first picture.

Thanks!

20774 said:

That's odd! I stopped looking at the first figure. Oh well... This is obviously someone's own typing but using the figures as needed. I guess they just didn't list the correct elements of the speedo in the first picture.

Thanks!

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it did make sense.
first pic was a general overview of all the rider's compartment area.
fig 5 was the detail of what was stated as #2 in fig 1.

sam314 said:

I'm looking at a 1972 R75/5 to join the other bikes in my shed. The PO is asking $3500 for it. It looks to be in good shape. Snip...

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It sounds as if you've found a decent bike but for me, theres not enough info to give me a good idea of whether that particular bike is a good buy or not. Just remember the old adage: Condition, condition, condition.

At the $3500 level, in this economy, I'd be looking for a /5 with no outstanding mechanical issues, decent but not perfect paint and a few period extras, including bags and bag racks and maybe a fairing, etc.

Please note that I'm not saying "Don't buy the bike" but I'd estimate that having to buy those accessories after-market is going to add $500+ to the real cost of the bike.

As I see it /5 prices have been steadily on the rise for a while but they're currently being held in check by the crashing economy. I'm seeing plenty of nice bikes selling on the $3000 to $3500 range and thats right about I'd expect to pay for a complete and good running bike.

Good luck in your search!

You could purchase a 1984 R100RT in pretty good condition for the same money.

Much better bike.