Best BMW Airhead

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I got my recently acquired 84 R80RT running and took it for a ride yesterday. Usually it takes me four or five rides to start to get comfortable on a new bike, but I just couldn’t warm up to it. My 71 750 /5 feels so much lighter with more tractable power. Less buzzy, no stash compartment lids vibrating like a coming train. Now it’s ( the RT) on eBay and will be gone soon. I’ve owned a couple of R100’s that I really liked, but neither was an RT. I took the Norton out afterward and ripped around the empty streets at 4500-5000 rpm. Sooo much better and a young (20 or so) woman at the store said she liked the bike and wanted to see my others. I told my wife and she snorted with laughter. That never happens with a BMW. I’m interested in thoughts about the best airheads. I had an R90S that I didn’t keep long either. Tall first gear, hard on my wrists and too valuable to knock over. I think the R75/5, R90/6 and standard R100 dual front disk models are my favorites.
 
I have a plain vanilla 1983 R100. When I was looking for a BMW to buy I selected this model as I wanted one with the Brembo brakes, lighter flywheel, electronic ignition. I think I made the right choice.

I usually ride 2 up and it is a very capable and comfortable bike to travel on. I was expecting it to have more torque given that its a thousand cc twin. It goes OK if you rev it though. The Commando feels quicker up to about 80mph.

Ian
 
I got my recently acquired 84 R80RT running and took it for a ride yesterday. Usually it takes me four or five rides to start to get comfortable on a new bike, but I just couldn’t warm up to it. My 71 750 /5 feels so much lighter with more tractable power. Less buzzy, no stash compartment lids vibrating like a coming train. Now it’s ( the RT) on eBay and will be gone soon.

Surprising verdict, as the R80 engine is supposed to be detuned and less buzzier vs. the R75/6 engine (torque: 59 Nm@3500 rpm vs. 60 Nm@5000 rpm). There is a weakness in the valve and valve seat area of these engines prior to model year 1985 - maybe your valves are leaking? Unequal compression may cause vibrations and of course loss of power and torque.

-Knut
 
Carbs being accurately balanced is critical to avoid vibration on an airhead. Obviously check valve clearances etc before balancing carbs. Don't just balance them at idle, open the throttle a bit and check again.

Ian
 
All of the young women are well aware of the little known fact that older men on Commandos are 'sexual tyrannosaurs'... Wives have even kept this secreted from husbands their entire lifetimes.... I've only had the opportunity to rack up miles on 1 R100RT, which was an '80, and could find absolutely no faults with the fine machine, except my size 13's didn't fit it.
 
Encounter was on the Norton. She said it right in front of her mother too. Maybe they were fighting. I think the R80 needed a good carb balancing. Also the stash compartment lids rattled a lot. Mostly I probably need to just ride it for a week or so and get used to it. I spent the first week on the Commando terrified. The RT is on eBay now - orange 84 - if anyone wants to see pictures and a video. I think I priced it right at 1200 opening bid with no reserve. I got a higher mileage R100T in the sale that I think will make a very cool rider. I need to get rid of something since there are four airheads and the Norton in the garage. Pretty much a fair fight but I don’t want any spilled oil.
 
Surprising verdict, as the R80 engine is supposed to be detuned and less buzzier vs. the R75/6 engine (torque: 59 Nm@3500 rpm vs. 60 Nm@5000 rpm). There is a weakness in the valve and valve seat area of these engines prior to model year 1985 - maybe your valves are leaking? Unequal compression may cause vibrations and of course loss of power and torque.

-Knut
Valves leaking??? When did BMW stop welding the tulips of the valves onto the stems?
No, this is not a joke!
 
Valves leaking??? When did BMW stop welding the tulips of the valves onto the stems?
No, this is not a joke!

Valve/seat deformation and leakage is a well known problem with the airhead engines (Rxxx) following the ban of leaded fuel. This is especially true for the exhaust valves and seats. On BMW airhead engines, exhaust valves are made up of two materials, while inlet valves are homogeneous. I am not an airhead expert, but it seems welded exhaust valves were used right to the end of the line, 1997. Failure of the welded tulip/stem valve occurs rarely according to this source:
https://bmwmotorcycletech.info/valves.htm

-Knut
 
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