trip meter reset push button missing

[Jeanroux]

hello everybody,

as stated in the title, the trip meter push button (official terminology) is missing on the dashboard.
probably it's is somewhere, but where?

pics of the manual and the dashboard, not the same..

[Barry]

European models didn't have a reset button in the face glass. 

More sensibly, the reset actuator is mounted at the rear of the instrument out of the weather.

[dogshome]

Marking for answer, based on accuracy, build up, explanation, reassuring demeanour and star quality:

[Jeanroux]

I'll have a poke around.
Here's also a pic from the Belgian/Dutch manual, also with the button in the glass.

I loved reading the old manual, there was an optional lock under the tank (any suggestions for that?) and a helmet hook (gone?).
 

[Bob_Roller]

If there is no reset button the indicator glass front, it should have a rotary reset knob on the forward side of the indicator .

[georgesgiralt]

Hello Guys,
The OP pictured a tachometer from a 1979~80 model BMW.
At the 1981 model, BMW moved the reset button from the rear of the tacho (which was quite difficult to reach) to the front of the bezel, with it's button.....
So the manual is for a 1981 model and the bike is fitted with a 1970 model tacho.

[BPT]

The cable locks show up on ebay but can be expensive for what they are. From what I've read, they aren't that great for security but many people want them in order for their bikes to be "complete", like having the original, complete tool kit. I think the helmet hook thing is part of the grab handle, at least on some of them?

[Jeanroux]

Found it, small black thingy on the back of the meter. hard to get to because the fairing is a bit "in the way".
started turning the thing and magically the numbers on the front started changing ;-)
and now it's broken, it doesn't count anymore while riding. Did I break it?

[Jeanroux]

As this forum is purposely chaotic, I have another issue.
Do I have to add lead replacement to the fuel? 

[dogshome]

Which engine and year?

I have a 1981 R65 which may or may not be compatible. I had the heads off for an 860 conversion a couple years ago and the valves did not even need lapping. The rocker adjustment hasn't moved in 10,000 miles since. The heads had been off in the past 40 years (one of the head gaskets was upside down), but at how many miles? Did it get valve seats changed? Who knows. I chuck LRP in (when I remember) just in case. My friend does the same in his earlier R80. That also has a slightly dubious history with one small spark plug fitted where the original thread got chewed up and welded over.

[Bob_Roller]

What model year bike do you have ??
If you don’t know, post the last 7 characters of the bikes serial number, it can be found next to the oil fill port .
It’s a common problem to have the trip odometer stop working ,
The plastic gears are pressed on a shaft . After decades of use, they can start slipping on the shaft, causing the trip odometer to stop working, or not work correctly .
My ‘82 LS that I’m currently using as my daily commuter, the trip odometer quit and I put a piece of label maker tape over the numbers and use a dry erase pen to note when I filled up with fuel .
You don’t need to add a lead substitute .
Only caution that I have, is that the ‘81 model year had an new alloy valve seat, only problem with it, was that they didn’t transfer heat from the valve to the cylinder head .
This caused valves to wear at an accelerated rate .
My ‘81 R65 had to have the valves and seats replaced at 45,000 miles, 73,000 km ,
There were supposed to be three angles on the valve face, mine had one and worn to a knife edge .
Don’t know if this happened on all bikes or not, but in my case it did .

[Jeanroux]

It's a '79 model, I had a little chat with a guy the former owner recommended.
He knows the bike. I do have to use the LRP every thirth fillup (?).
So I'll do that ;-)

[georgesgiralt]

Hello,
On a French BMW forum dedicated to the old aiheads, there is a strong consensus not to use any lead substitute.
In a nutshell, they say that the valve seats are so coated by lead due to previous leaded fuel being used that you can ride several hundred  thousands of miles before needing any. And they also said that the valve recession problem has been vastly exaggerated and was at best a layer's precaution to avoid any suing...
I ran my 82 R65 for about 130 000 km without any and when I renew the engine, no valves had receded .
Of course, YMMV, but I for one would save the cost and hassle.

[Barry]

Valve recession is produced when micro welding occurs between the valve and seat and this is a temperature related phenomena. So it mainly affects the exhaust valves and because it's temperature related is more of a problem with the larger capacity airheads and when the engine is used at sustain high revs.

Conversely if you have a smaller cooler running engine and don't do sustained high revs then valve recession may not a occur at all. That's been my experience, I've owned my 79 R45 for 17 years and never used lead substitute at all, nor have I ever noticed valve clearances closing up measurably between services. 

I agree it's an exaggerated problem at least for the early bikes with cast iron seats.  BMW's first attempt at lead free seats performed worse than the cast iron ones because the thermal conductivity was poor which brings us  back to the problem being temperature related.

The inference is obvious, if you are going to be running an airhead engine very hot because of  sustained high revs and in high ambient temperatures then valve recession may be a concern  but  it's not a given that problems will occur in more moderate use.