BMW K75 with sidecar

[JohnC]

I like the way you deal with your ailments... side car! rather than stop riding......

Yes, indeed. And a side car rig, as opposed to a trike.

I missed the Earles fork the first time I looked at the picture. What is the advantage of the Earles fork? Considering that the stock bikes came with conventional telescoping forks, there must be some advantage.

Always surprised the K75 did not have a longer life.

K75 production ran from 1985 to 1995. That is not bad. I don't know how many of those years it was imported to the U.S. though.

Power output is about 70 hp - more than adequate for a sidecar rig as long as you are not in a big hurry.

One of my riding partners in Germany had one. She loved hers. Her only complaint was the usual BMW complaint - servicing to maintain the factory warranty was pretty expensive.

 

[charlie b]

And, if I remember right, there was a rear drive seal or bearing issue. Don't remember what it was but it was an easy fix and might be especially important for sidecar duty.

 

[Phil Tarman]

Remembering that Bob Higdon says that the NT is the K75 BMW should have made makes me wonder how the NT would do with a sidecar. It sounds to me as if Hannigan could make it work.

 

[charlie b]

Yep, I think the only issues would be frame mount locations and forks.

 

[EX Winger]

Katherine,

That is absolutely beautiful!! I will hope it is as good as it looks, What is the milage on the K-75? I will also be interested on y our comparison with the Ural after you have time to make a good comparison.

Ride Safe,

Eldon

 

[elizilla]

The photo I posted shows it from the good side. Here's the other side:

Maybe you can't see it well enough there either. But the bike is pretty beat up. It has 106,000 miles, and a rebuilt title. There's an injector cover that was installed upside down and backwards - no idea why. It's covered with kid stickers and the ones I have peeled off so far, were covering scratches that were touched up with the wrong shade of turquoise. The black engine cover is very faded and the seat has some rips. The rear brake barely does a thing. The low battery light comes on when I brake.

So, it's going to need some *stuff*. People on the BMW forum are telling me I should have a reputable professional mechanic go over it. Shyeah, right - if I find a reputable professional mechanic willing to work on a 26 year old bike, he's probably got unicorns in his toolbox. And I can't afford him anyway, since this bike needs just about everything. LOL!

But when they installed this sidecar they did a *stellar* job. Compared to the Ural it's like night and day. It rides straight and feels fast.

 

[Herb]

I suspect the BMW Forum doesn't yet know what we know. You are THE MECHANIC! Enjoy.

 

[bicyclist]

The seat is weird. It looks like somebody did a low seat conversion using the original "comfort" seat. I'll bet it's awful.

 

[elizilla]

The seat would be comfortable if it were six inches higher. But at that height it's like sitting in a hole. It is on my list of things to do something about, but I am very busy right now so it will be a while.

 

[elizilla]

Yesterday I went over it to see what's what, and cleaned it up. I wanted to check the oil but this turned out to be easier said than done. It has a sight glass, which is blocked by the sidecar. I could only see the bottom half of it. Either there's oil in it or the glass is oil-colored. I could not see the top of the oil, and it was too dark to see with a mirror. I will have to tackle this project again with a mirror, a different flashlight, and perhaps a second pair of hands to hold the flashlight.

I checked the tires. It has a new rear tire that looks good, but was at only 25psi. The bike's sticker says it should be 42, so I added some. I didn't find any damage, so I don't think it's leaking. Still, best keep an eye on it. The sidecar tire was at 25 as well, and I couldn't find anything saying what it should be filled to, so I left it alone until I read more of this paperwork. The front tire was at almost 30, and should be at 32, so I added a little. The front tire is not down to the wear bars but it is obviously worn and there's a little bit of cracking action starting in the tread recesses, so I will probably get a new front for it soon.

The rear brake, which is almost completely non-functional? I think it may be adjusted badly, but I couldn't figure out how to change it, so I will have to read manuals and look again later.

I got the Givi plate off, and removed the side bags. I'll hold onto the side bags just in case, but I have sold the Givi topcase to a local friend, because I already own several Givis and don't need another. I can't really see a need for any cases on this bike since it has a huge trunk.

And speaking of trunks, I went through the trunk to see what all the mysterious bundles in there were. There are two motorcycle covers. I didn't unfold them. Perhaps one is for the bike and one for the sidecar? There is a black and purple rainsuit that stuffs into a built-in pouch and turns into a fanny pack. Size medium, and if it has ever been used it wasn't a dirty day. I wonder if it belonged to whoever had the bike lowered and put this deeply dished seat on it? There is a nylon duffle bag that proved to be full of BMW parts - some used, some perhaps new and have just bounced in the trunk for years. A pair of front brake pads with lots of life left in them. Rear brake shoes that look new. A bundle wrapped well in newspaper and packing tape, labeled "clutch" which I didn't unwrap, but it does indeed feel like a stack of clutch plates - no idea if it is new or used. A wheel bearing in a box labeled "used". Some obviously used radiator hoses.

The front and rear suspension both have aftermarket shocks, labeled "Progressive Suspension". A reputable brand.

I did not dig into the wiring, though I need to do that. It has obviously had some mods, and I have no idea if they were done properly or not.

I didn't detail it but I cleaned it better than it had been cleaned in a while, I think. I still have a couple of cans of S100 engine brightener from when I used to polish the Sabres. Newer bike engines don't have that black coating that was popular in the 80s, which responded so well to S100, so these cans have sat on a shelf for years. The BMW has that kind of engine finish, so I sprayed it. Looks nice. I waxed some of the painted bits, but got bored before I finished. Does wax really truly do anything, or is it just an illusion caused by the fact that it goes on hazy and the shine comes back when you wipe it off?

 

[bicyclist]

1. Oil sight glass - They become discolored and they eventually start to leak. The thing is just a press fit into the case with a rubber seal around it. When they get leaky, it's a good idea to replace them because they can blow out. It's an easy fix. the sight glass has a red dot in the middle and a circle. The book tells you that the oil level should be somewhere in the circle. Experience has shown that it should not be above the red dot in the middle or the engine will just get rid of it.

2. Rear brake - If that is an 87, it will have a drum rear brake. It uses a standard rod and wingnut adjuster.

3. Injector cover - That is not a stock part. The bikes didn't come with one.

4. Valve cover - That one is painted black. In 87, they were not painted.

5. S100 - It works great, but don't use it on unpainted engine parts when the engine is warm; it will stain.

6. Seat - It appears that someone did some kind of low seat conversion. The rubber thing on the back of the tank is not there with a standard seat, there are side covers that go below a standard seat and there's a tool tray under the seat. Under the tool tray is a space for the fuel injection brain. With the low seat, there's no tool tray, only a holder for the brain. The seat lock/latch is different, as well. You could remove the rubber tank thing and replace the seat with a standard seat and live without the side covers and tool tray, but you'd have to do something about the seat lock/latch. I can't remember the details.

7. Clutch - That thing has a single plate dry clutch. If you have a package that feels like a stack of something, you may have a clutch plate and pressure plate. The clutch splines should be lubed with a touch of Moly 60 about every 40K - 50K. The driveshaft splines should be done every tire change or maybe every other. That's one of the important maintenance items. It's easy to do. In fact, it's one of the first things you should check.

If you have questions about that bike, I may be able to dredge up some answers from the dark recesses.

edit: And these guys are a good parts resource: http://www.beemerboneyard.com/

 

[bicyclist]

and a rebuilt title

Aha! Just noticed that. It explains the weird things I see.

 

[bicyclist]

Definitely hang onto the sidebags. The rear rack is a desirable Reynolds rack. Keep it.

 

[elizilla]

George, thanks for the advice!

There is a mechanism, not pictured, that splices the sidecar brake into the rear brake of the bike. It uses a cable that is pulled when the rear brake lever is applied, and this cable compresses a master cylinder and a hydraulic line goes somewhere out of sight. This cable was limiting the brake lever travel and stopping it before the bike's rear brake did anything. I don't know what the sidecar brake uses; I cannot see it. Need to figure out what is a good jack point to lift the car wheel and take the wheel off to see behind it. Whatever mechanism is in there, doesn't do much. My thought yesterday was to loosen that cable, but it was already at the loose end of its travel. Today I suddenly went "Doh!" and tightened the wingnut. It was a matter of seconds once it occurred to me to look there - I had let myself obsess on that darn sidecar brake cable and missed the obvious, last night. Now the rear brake on the bike works quite well. I still need to examine that sidecar wheel's brake and figure out why nothing happens there.

If I can find the right forum to post in, I might be able to trade this low seat and hardware for a higher seat and hardware. Otherwise, I might just have a local upholsterer add a couple inches of dense foam to this seat. I definitely need to get it lifted up higher!

Did the FI have issues, back in the day? Or could someone have downloaded a wrong map into this one? It has lean popping on decel, but otherwise seems to run a bit rich; I can smell it. It *feels* good, though - I haven't noticed any surging and there's none of that abrupt roll-off that some FI bikes have. Does it have an O2 sensor somewhere or is that a modern FI bike thing that they didn't have in 1987? Maybe someone defeated some emissions things to get it like this?

 

[bicyclist]

The FI didn't really have any issues unless someone messed around with the throttle bodies. They were set up on a flow bench by the factory. Sometimes the rubber mounts get leaky and need to be replaced. You can spray a little ether on them. If the engine speeds up, you know you have a leak. Not a good thing to do inside a garage.

No O2 sensor or fancy emissions controls on these bikes. I'm not aware of any way to remap them either. They are what they are. Back in the day, about the only thing that was done was to tweak the mass airflow sensor pot a bit. Don Eilenberger and Whatsisname I can't remember are a couple of K75 gurus. They had access to a dyno and decided to see what they could do to coax a little more power out of the thing. After spending hours changing exhausts, fiddling with intake and so forth, they concluded that it was all a waste of time. The bike runs best if left stock. If it starts running ratty, the first thing to check is that the connector to the fuel injector brain under the seat is firmly seated. There's a little brass colored clip that retains it, which you should be able to see through a hole in the top of the plastic thing the brain sits in. It needs to be properly clipped around a nub on the connector.

Poke around on this website and you can find a wealth of info. http://www.ibmwr.org/

It's a good source to buy and sell and there are tech articles.