Hi,
I'm new to the forum, as well as the BMW K-bike series, an appreciate finding a forum dedicated to the older K-bikes. Past bikes include a 1993 Yamaha FJ 1200, a 1998 Ducati ST2, a 1998 Ducati 900 supersport (#35 of 300 built), a 2003 Honda VFR 800 Interceptor, a 1981 Suzuki GS 500E, and a 1974 JackPiner (175cc) Penton. I loved them all.

I have been without a bike for the last two years and by chance/good fortune, found this lovely, seemingly well maintained 1986 K 75C. The bike has 90,154K on the clock and came with all service records up to present. An extra set of keys, owner's manual, Clymer shop manual, new Michelins, a servicing of all fluids from front to rear, no leaking of fluids that I can see, a complete tool kit with tire repair kit, and in general, pretty darn good overall condition. All for the bargain price (I think) of $1350.00 US dollars. I purchsed the bike from the second owner, who has owned/maintained the bike for the last 18 years.

Now that I have had the bike for a few days, there are a few issues (expected there would be) that will require attention. Upon deceleration or braking (even light braking) the front end dives south and is way too eager to do so. If you know what a pogo stick is, that pretty well describes the bouncy nature of the forks....too loose for my comfort. I'm thinking progressive springs replacement with perhaps a thicker fork oil? I'm open to all suggestions or advice on tightening up the front end.

Another issue that is puzzling me; gas above the flapper when I opened the tank to fill her up. The tank had abount 2.5 gallons when I stopped to fill up. Not sure what that is all about, should I be concerned? Judging by the paint discoloration on the top of the tank, I think gas escaping from cap has been an issue in the past.I thank you in advance for any an all expertise you care to share with me as I become familiar with what I think is going to be a terrific motorcycle.

Keith

Hello Keith,

First, if the bike is in good shape, I would say that you got it at bargain basement price.

Most of the people on this forum are riding K100.
Because I am one of the few lucky one to own a K100 and a K75, I am familiar with some of the specificity of the K75. Even if both bikes share the same technology and a lot of common parts their are slight differences.

For the forks, yes going with progressive springs is definitely an answer.
You have to be careful about what you read on forks for the K75. It depends on the year of the bike.

In 1990 the specs were modified.

travel of the front forks:
Up to 1989: 185mm
After 1989: 135mm
This is 50mm or almost 2 inches difference.

Up to 1990, The forks took 330cm3 of oil per side.
from 1990 and up, it took only 280cm3 per side.

If the mechanic didn't paid close attention to the year, he may not have put enough oil in the forks.

The discoloration of the paint on the tank is "normal". Their is a small hole to vent the tank, and the gas vapors are discolorating the paint around the gas cap. This is a common problem.

Enjoy your new bike.
Bert

Hi Keith,
With any second-hand bike the mantra to chant is fluids and filters, fluids and filters. Regardless of all of the promises sworn on a stack of bibles by the previous owner, go through the bike from stem to stern and replace all fluids and filters. Change the fork oil to the genuine stuff and then you have a starting point to compare with since unless you helped with the service the nature of the fluid is unknown. Same for brake fluid, all three sets of oil in each part plus new air and oil filters. Whilst you have the tank off treat every electrical connection with DeoxIT including all of the relay bases AND the big common earth points such as under the tank. Doing that will ensure the bike will be as reliable as you can make it by servicing the consumables.
Regards,
K-BIKE

Hello Bert and K-Bike,
I appreciate the info and agree that changing all fluids, if for no other reason than, to get aquainted with the bike and having a starting point is the prudent thing to do. While I'm checking the various systems out, I may as well put a good cleaning on her as well. Any suggestions on products that will do the business on cleaning the wheels, valve cover, driveline, etc? Thanks
Keith

All of the usual car cleaning products from the top line companies Mothers etc. work well. You can buy DeoxIT from a Caig Laboratories distributor.
Regards,
K-BIKE