Brand new ‘91 K75 (with 87,000 miles on it)

[TheZiggen]

Hello,

I am a new BMW owner, having recently purchased a ‘91 K75 with 87,000miles on the odometer.
It seems to run great, far smoother than my previous two bikes. The previous, and second, owner seemed to be rather meticulous about caring for it, but any vehicle needs special attention when the miles get up there. I was just wondering if there is anything in particular I need to listen/watch for on this model. I intend to take it on a 2,000 mile trip this summer and want to spend as much time as I can getting it in the best shape it can be. Also, I do have AAA with motorcycle coverage and will be traveling with a group before anyone cautions against taking such a long trip.

I was also interested in getting some idea of what most BMW owners do when purchasing a used bike, is it worth it to take it to a dealer for a once over? Do most do their own repairs? Either way, I definitely intend to do my own regular maintenance, I’m rather new to working on bikes but have always cared for my own cars. I would really like to know where to find a shop manual for this bike. I have struggled to find one this far and I was wondering if that’s just a BMW thing. Anyone know if the Clymer or Haynes manuals are decent? They appear to cover every model year of both the K75 and K100, so I don’t imagine they would be that thorough.

Also, as well as being new to BMW, I am also relatively inexperienced at posting on forums. Feel free to give me a stern talking to if I am violating some sort of etiquette.

Any info at all is appreciated.

Thanks.

 

[lee]

Welcome to the forum from a previous 1991 K75S owner.

 

[Omega Man]

Welcome to the forum Adam...For some reference on posting, you can look here- https://forums.bmwmoa.org/showthread.php?72733-How-to-post-on-the-MOA-Forum
If you need anything else, just ask.
Gary

 

[pglaves]

There are two areas of weakness in those bikes:

1. The splines where the driveshaft connects to the final drive pinion shaft are prone to wear. You should remove the final drive and clean these splines and lubricate them with a good moly grease. And then do this every time you get a new rear tire.

2. The electric radiator fan motors tend to fail because they don't run very often and grunge gets into the front shaft bushing causing the fan to bind up. With everything off reach in and spin the fan by hand. If it doesn't spin freely it may have already failed or might be about to fail. If it does not spin readily you should remove the fan from the back of the radiator (requires radiator removal) and bench test it after lubricating the front shaft bushing.

Also, water tends to collect in the lower left front corner of the fuel tank. Use a dose of IsoHeet in the red bottle to absorb any water and prevent corrosion.

And finally, the original rubber dampers in which the fuel pump mounts are prone to dissolving in ethanol laced fuels. It is a good preventative to get an alcohol proof damper from Bob's BMW (or other vendor) to avoid future problems with black goo in the tank and fuel pump.

 

[98lee]

You might want to let us know what town you live in or are nearby. Someone might be able to give you a hand looking it over and get it in top shape.

Valve adjustment needs to be checked to insure that the exhaust valves don't get too tight.

The Clymers manual for theese bikes is very good.

 

[jpdicarlo]

A bit obsessive perhaps, but I have a routine I perform any new K I buy.
With the exhaust mounted to the underside of the engine, the manifold's nuts are "out of sight, out of mind." They corrode over time and can seize to the studs. Not an issue until you want to remove the exhaust for some needed service. I've had bikes with missing nuts, broken studs, and horribly rusted assemblies.
I put a socket on all of them, take them off in turn, and slather the threaded stud with never-seize. I typically have to replace a couple of the nuts as they are just too rusted to go back on. The new ones come with a nice coating of copper, as BMW has obviously recognized there's a problem here.

 

[TheZiggen]

Thanks all for the information. I will put it to good use.

 

[stokester]

Clutch Cable

In addition to the previous recommendations I would check the valve clearances if it has not been done and clean/lube the clutch cable barrel at the lever.

It's happened to me twice where the clutch cable has broken while on a trip. Fortunately I've always carried a spare and was back on the road within an hour. While it's good practice to clean/lube regularly it is easy to forget and even a slight binding there will cause the cable to fatigue.