Show Us Your Motobricks

[Quiltzig]

Thanks Moto 949,
I have zero vibration in my wifes K75S (which is what I am riding at present) - we are both pretty lightweight - I am only 72kg and my wife is 55kg
Next tyre change I will swop out final drives and see what I think of the change. As I have a spare it is only a half hour job, and it would be interesting. Our roads here are quite winding and hilly, but I find the gearing especially in second a bit too low, so this might help raise it to a better level. Like you said, these bikes are not that powerful, but the power in the midband is very usable. Put it this way... if guys are pressing on pretty quickly I can generally keep up with them OK. On my K1200RS they have less even less chance of getting away from me.
The new K75S Café racer project will hopefully give me a better sporting weapon. I plan to lose between 35 and 50kg of flab from it, and with a decent tune it should go quite well.

[rbm]

Transmission Gear Ratios:  For K100s the transmission gear ratios of 2V and 4V transmissions are the same (Gearbox Ratios  4.50 / 2.96 / 2.30 / 1.88 / 1.61 : 1).  The only difference in gearing between K75s and K100s/K1100s is in the ratio of the fifth gear.  A K75 has a 1.67 gear ratio for fifth gear while the four cylinder K bikes have a slightly "taller" 1.61 ratio for fifth gear.  The gear ratios for gears 1-4 are the same.  This is about a 3% difference in fifth gear and not very noticeable.

Final Drive Gear Ratio:  On monolever final drives the gear ratio is stamped into the final drive on the top front where it meets the swing arm.  On paralever final drives the gear ratio is stamped into the flat surface around the breather cap on the top of the final drive.

Two of the more prevalent gear ratios (there are a few others) in 4V paralever final drives are 31/11 (2.82 - commonly found on K100RS4Vs and K1100RSs) and 32/11 (2.91 - commonly found on K1100LTs).  The higher the gear ratio the more torque will be available at the rear wheel.  You'll get lower RPMs for a given speed and slightly better mileage with a lower gear ratio.

Since K100s usually have a similar gear ratio and 90 hp the torque at the rear end will be the same if you use a paralever with the same gear ratio.

Most K75s have a 32/10 (3.2) final drive which is significantly "shorter" (has more torque) than the highest gear ratio available in a paralever final drive, 2.91.  So if you convert a K75 to a 2.91 paralever final drive then the amount of torque available is reduced by about 10%.  Since a K75 only has 75 hp there is a noticeable performance difference between the 3.2 monolever final drive and a 2.91 paralever final drive. On the flip side you'll get correspondingly lower RPMs for a given speed.

Theoretically on a K75 you should see a noticeable improvement in mileage but I really can't say for sure because I use my paralever K75 as a city bike and run it in lower gears at high RPMs to make up for the loss of torque.  That and I never bother tracking mileage when city riding anyhow since there are so many variables involved.

More information about gearing available from Anton's page.

[moto949]

Hi again TrueAce,

Rode the K75S today. On the speedo; 60 mph = 3550 rpm (just barely over 3500). Now as you'll recall, I had my GPS app tell me that my bike's speedo reads 64 mph while the GPS shows 60 mph, so I checked my rpm at the speedo's reading of 64 mph (a true 60 mph) and that rpm was 3800.

[HYPERR]

My 1995 K75S in Arctic Silver

[TrueAce]

Wow, that's beautiful! You need to show more pics.

[HYPERR]

Wow, that's beautiful! You need to show more pics.

Thank you TrueAce, here are a few more pics.   :riding:

[TitanBlue]

My 1990 K75S purchased in 2012, done a bunch of stuff to it but luckily had a good bike to work with.   Now has 83K on it.



https://flic.kr/p/K2GURS

https://flic.kr/p/Jwm79v

[thecableguy]

Here's my new (to me) baby...  It's the only pic I have so far, the one the stealership took when we bought it.

86 K100RT

[The Dude]

A very well preserved '86!'bought mine new and haven't looked back,unless I'm on my Guzzi (for the bits that fall off.)
The stealership woulda made sure it's good to go so your in for some great times.ask about the drive spline lubing,if you haven't already.Keep the motor spinning and watch the colossus when walking it around.All the best.

[TrueAce]

Beautiful bike, really sharp! How many miles? Curious about how a dealer had that for sale. Bikes that good usually are FSBO.

[Martin]

Nice looking ride should give you years of faithful service if you maintain it.
Ride long and prosper.

[thecableguy]

The dealer said (taken with a big grain of salt, big grains...) that the owner had several older Beemers but was looking at a new one.  They didn't really want to take it in trade, but with as clean as it was they took a chance. 65K miles on it, although the speedo is doing the usual wacky thing.

I cleaned and tightened the three pins in the speedo and that mostly worked.  Still not working 100%.  Going to go thru all the connections from the rear wheel forward this weekend.

It's a bit hard downshifting sometimes, from what I hear that's likely dry clutch splines.  Gotta make room in the garage to work on it, looks like a time-consuming job.  But I'll get those and the rear shaft splines lubed at the same time.

Still, I enjoy wrenching (not as much as riding of course) and maintaining it should be easy.

Nice riding a big bike again. Been riding 50 and 150CC scooters for the last ten years or so.

[The Dude]

Sounds like you're on ya way.Riding small bikes is the best apprenticeship as you are forced to learn the skills that big bikes don't teach you.Road Craft.

[Batkinson]

mine is classic green 1985 K100....just acquired

[The Dude]

'Nother nice one.Wow.44000 miles!Standard colour?underseat is the code.

[Batkinson]

Assuming color id orig. here is code, though i could not find it on the color code lists I could find. I did find an obscure reference to Toscana Green color scheme but no referent code.

[Batkinson]

and of course i found two other green color references just after posting...... Yucca Green Pearl, and Madison Green Metallic.... but no samples to compare to mine.

[The Dude]

Thanks for the colour feedback.it's An uncommomon standard one by the look of the unmolested stickers.Very nice.

[Filmcamera]

Dolomite Grey (Metallic) 175 579 / 175 1985 On Models, K100, K100LT, K100RT

http://www.bmbikes.co.uk/paintcodes/greys.htm

Doesn't look very grey to my old eyes but there you go that is what paint scheme 579 is according  to the charts

[Batkinson]

Thanks for the info, doesn't look grey to me either...but there it is.

[bikesnbones]

How about posting a photo of your bike in the Klassic K-Bike section, bikesnbones? It's interesting to see what other members are riding.

Laitch

OK then
 :riding:

[JourneySA]

First ride with my "new" '84 K100rs - loving it!!!!

[Inge K.]

First ride with my "new" '84 K100rs - loving it!!!!

See you have the genuine rear brake disc.....those was prone to crack.....keep an eye on it.

[Soichiro]

Just bought this last month.  Haven't done a lot to it yet,  apart from a seat cover (old one split) and a screen (cracked)
After Christmas,  I plan on tidying up the paintwork,  getting some 2K paint and firing up the compressor.   Anyway,  here's some photos to save you lot having to buy bike magazines.

[Laitch]

Welcome, Soichiro! How many miles on the bike? Put the model year in your profile, too, because parts can vary from year to year.