My 92 K100RS 4 valve has some of the most aggressive engine braking I have ever come across on a motorbike.
I have been told that this is just the way they are but coming off throttle to suddenly makes the bike visibly nose dive.

Also when up shifting it is very difficult to get a smooth change unless I don't use the clutch. When downshifting also i am struggling to get a smooth change. The bike itself runs very well but I was wondering if their was something maybe on the fuel injection side that could be adjusted to give a better smoother ride?
Would it be advisable to change the gearbox and final drive oil for fresh to maybe improve things?

SC

The quickest way to shag a K 100 gearbox is by not using the clutch. Make firm and positive shifts just touching it through doesn't work on a Brick.
You may need to lube the clutch spline as they get dry and that makes very hard shifting, especially down shifting and into the lower gears.
You will need to remove the gearbox to get at it. Have a search of the forum there are some good write ups on the subject. I think Duck has one called "splientology".

Hi heyskull.first things first .If you don't know the service history then defo,change gearbox oil (use a magnet in the oil just in case of little nasties) Have the forks serviced to make sure their working OK, Is the clutch cable set correct, light and smooth without drag,I add 200ml of MOLI SLIP to the box works very well.When changing up/down DON'T close the throttle fully,with a bit of practise you will find a sweet spot this gives a smooth gear change.You dont say at what revs/gear you are ridding 
eg,i can run say 20 mph in 5th and just pull away no problem or run 5/6 thousand in 5th shut throttle without much frontend effect.Golden rule with Ks little things make a big difference
Hope some of this helps.

It had a clutch in 2000 miles ago. When I first got it I had it serviced and for its MOT it had new forks seals and oil. So I am going to change the oil on the gearbox and rear drive and learn to ride smoother.

I was thinking of some sort of damper on the throttle so as it goes back to idle gently not just like it is at the moment all of a sudden.

SC

HI again,when i had carpel tunnel problems i set the throttle a bit stiffer by tightening the bar end ,
slacken the bar end push it towards throttle and retighten this will help.A few attempts might be needed.Do this with bike on stand,don't forget to change back for MOT they don't like it to be stiff.

The final drive gear oil should have no impact on shifting.

To get it shifting as smoothly as possible use some good synthetic 75-140 gear oil with some moly gear oil additive.

Is it the same oil for gear box and final drive?

How much in each?

SC

RicK G wrote:The quickest way to shag a K 100 gearbox is by not using the clutch. Make firm and positive shifts just touching it through doesn't work on a Brick.
You may need to lube the clutch spline as they get dry and that makes very hard shifting, especially down shifting and into the lower gears.
You will need to remove the gearbox to get at it. Have a search of the forum there are some good write ups on the subject. I think Duck has one called "splientology".

Heyskull,

You didn't mention a spline lube during your recent service. This is from the pdf of the "splientology"

"For both 2 and 4 valve K bikes the clutch friction plate slides along the transmission input splines as you let the clutch out. Therefore, these splines are subject to wear and should be kept well-lubed. A common symptom of them requiring lubrication is difficulty downshifting or "false neutrals" (ending up in between gears) when downshifting, usually on 4
3 or 3
2 shifts. If you're new to riding K bikes then this symptom may be hard to recognize."

Get the pdf here:


http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/splientology/splientology.htm

heyskull wrote:Is it the same oil for gear box and final drive?

This is a question that can be answered in the pages of a rider's or workshop manual. Here's a link to the rider's handbook for your model, compliments of forum member duck.

heyskull wrote:Is it the same oil for gear box and final drive?

How  much  in each?

SC

Same oil in both. You will need a little over 1 litre so you have to buy 2 litres.

Final drive you fill up to the threads on the filler cap hole.
Gearbox the level is measured by the c spanner for the rear shock. Its also the dipstick. If you don't have one its 116mm from the top of the filler cap hole to the top of the oil, you can use a screwdriver with a mark on it but do NOT use one with detachable heads. If the shaft falls in you cant get it out.

also google about bypassing the TPS sensor. Easy to do by rotating the switch.

The k100, on a closed throttle, cuts fuel under 2k revs.  This causes the nosedive you are talking about.  Also, if you are running under 2k revs in normal riding you are in too high a gear. The bikes like to be at 4k upwards (Its not a car). There are a lot of articles and forum posts regarding this as well.

If you bypass the TPS sensor/switch it makes the bike much more like a "normal" bike.

Corkboy wrote:also google about bypassing the TPS sensor. Easy to do by rotating the switch.

Heyskull's '92 RS doesn't have a switch that can be rotated. His moto has the same potentiometer that the K1100 uses.

He might mitigate the diving by servicing his moto's fork tubes and perhaps changing the weight of oil within them. A faulty rear shock could be contributing to diving also. Finesse with the throttle also helps.

The Motronic system has a throttle position sensor zero test built into it.  I believe you ground one of the pins on the diagnostic connector and watch the temperature light as you open and close the throttle.  The test is important to synchronize the Motronic's fuel map with the air entering the engine through the throttle bodies.