Any inherent K75 design issues to be wary of?

[rbm]

Hi,

I'm going to look at a K75 this week. It's an '87 "C" model without ABS. I'll be looking for the "usual suspects" when going over the bike but I'm putting the question out there as to whether there are inherent design issues with that K75 model year that I should be wary of. For example, the K100's have chronic fan issues with disuse, 6-bolt output shaft that tend to break (later 12 bolt), 16 teeth in the rear drive input spline (later 20) and other issues resulting from BMW design decisions that become more apparent as these bike age. My familiarity with this marque is limited to the K100, knowledge which may not translate to the K75 models.

Cheers,

[frankenduck]

You won't have the engine drive shaft issues.

Fan is the same.

It will run much more smoothly.

Other  than that it's a K100 minus one cylinder with a rear drum brake.

[argent brick]

I don't know if it is true, but I have heard that by 1990 BMW had all of the bugs worked out the K75. If this is the case, I would recommend bikes made between 1990-1992. I know you get a rear disc brake on the newer bikes.

I own a '95 and don't find many used parts for it. If I had to do it again, I would by '90-'92.

[frankenduck]

What "bugs" were worked out that you know of?

They changed the rings in 89 so oil wouldn't seep past them.

They went to the S forks in 90 and the Showas in 92.

Personally I'd get a 94 or 95 since it's got the 50A alternator and is newer.

I had a C with rear drum.  It's not as easy to lock up as the rear disc is so I never really thought of that as being inferior, maybe even a little better since it gives you a little more feel - and you'll never have a leaky rear master cylinder.

[Chaos]

I understand the 86-87 K75's had a shift drum that was a slightly softer alloy, leading to bent shift forks.  88 and on had a harder drum. 

[Rick G]

I have seen quite a few early K100s and K75s that had a straight aluminium drum but my K100 (1990), K75RT (1993) and K1100 have an aluminium drum that is hard anodized but I have never heard of this being specific to K75s. I can't recall doing a gearbox on an early K75 so I can't be sure of what they have.

[argent brick]

Frankenduck,

I guess "bugs" was not the proper term to use. "Improvements" would have been a better use of the English language.

An improved instrument housing, upgraded alternator and reworked piston rings are the sort of things that I was thinking about. I think you listed everything that was on my mind except the speedometer. I was under the impression that those changes were all done by 1990. I stand corrected.

I think I would still recommend 1990-'92 because I am finding many more used parts available for those years over
93-95.

My boxer had drum brakes front and rear and they sucked. Disc brakes are a huge step forward for me.  I never would have thought about the difference between disc and drum the way you did. I passed up some great buys on
bricks because they had rear drums. Thank you for the words of wisdom. I need to read more of your comments.

[rbm]

Thank you for the replies.  They have been helpful.  I'll make sure to check the shifting on the gearbox as I wouldn't want to buy the machine if it had a bent fork and shifting problems.

@duck and @argent:  A rear disk would be my preference because that's what I have on my K100 and what I am used to.  However, I use the rear only for low speed maneuvers and the very last stage of complete stopping; otherwise all front braking.  A rear drum would not be a detrimental feature of the bike considering the way I brake.

I agree about the 90-92 model years, @argent.  I would love to find one here in Canada but K75's are few and far between on the used market.  I saw a 92 beauty located in Ohio on CL yesterday (5 hours drive from me) but importing that into Canada is time consuming and expensive.  For example, BMW charges $500 for the mandatory Recall Letter  :eek2:. Then there are the RIV fees, taxes, transport costs, etc.

[frankenduck]

argent:

Yeah, you're right. I forgot about the speedo venting and contacts.

I don't think the piston rings are that big of a deal.  My K75 has an 88 motor and it kind of cracks me up when it puts out the mosquito fogging for the first few blocks.

[argent brick]

When I was looking for a K75, the changes were a big deal. Now that I own one, I don't think they are that big of deal.
Well, maybe the alternator if you are going to run extra electrical goodies.

Today, I would just buy what I could find in my price range and worry about overall condition and what repairs are needed.

[sch]

Thank you for the replies.  They have been helpful.  I'll make sure to check the shifting on the gearbox as I wouldn't want to buy the machine if it had a bent fork and shifting problems.

@duck and @argent:  A rear disk would be my preference because that's what I have on my K100 and what I am used to.  However, I use the rear only for low speed maneuvers and the very last stage of complete stopping; otherwise all front braking.  A rear drum would not be a detrimental feature of the bike considering the way I brake.

I agree about the 90-92 model years, @argent.  I would love to find one here in Canada but K75's are few and far between on the used market.  I saw a 92 beauty located in Ohio on CL yesterday (5 hours drive from me) but importing that into Canada is time consuming and expensive.  For example, BMW charges $500 for the mandatory Recall Letter  :eek2:. Then there are the RIV fees, taxes, transport costs, etc.

@rbm you don't need a $500 recall letter from BMW if the bike is over 15 years old. Because it is 15yrs or older, you also dont have to do a riv. You still need to do paper work in advance to import though. I imported a k75 from upper ny to Ontario last fall. It was easy and not that expensive. Much more selection and better prices in the states.