27hp = the restricted version for sale to learners on restricted licenses. It could be easily de-restricted by the dealer when the time came.

Hi everybody,
I am from Italy (and new comer to this forum) and since 2004 I am riding a R100GS (1991): it is a funny bike, I can really go GS (in and outside the pavemented road)...

But... there is one aspect against...

Why this bike vibrates so much!? Vibrations are particularly irritating at the hands, when driving at 130/140 km/h and over...
This unpleasant "detail" makes the bike not comfortable at all for long trips.
Perhaps the vibrations of my bike are exceptional for some reasons I do not know.

Is anybody willing to give me some advice on how to reduce such a problem?

Many thanks, Superciuk

Yours may be worse than normal - or normal - hard to say - find someone who is an expert on the bike and get their opinion. Carb adjustment is the number one cause of excessive vibes - but they DO vibrate. The R80 is MUCH smoother.

This should possibly a new topic, but the horizontally apposed engine is naturally balanced and is one of the smoothest engine designs.
It is very important though that the weight of the conrods and pistons should be the same.
The conrods is more involved as far as their balancing is concerned as a large part of the conrod weight(bigend) rotate with the crankshaft, called the rotating mass, and a smaller part of weight(smallend) is moving back and forth with the piston, the recipocating mass.
To balance the conrods they should not only have the same weight but they have to have the same weight distributed between the bigend and small end sides.
To balance the Pistons and conrods is a very inexpensive and qiuck job. It get's done by removing material of the heavier items in a area where it does not effect the strenght or working of the engine.
The biggest job is to remove these items from the motor which is easier done than on any other engine.
The only reason why an opposed motor vibrates is because the pistons are not directly opposite each other.
The smoothes bike I have ever ridden is a old R80GS with the HPN 1040cc Malhe convertion
At 100km/h you could not feel any vibration through the handelbar or footpegs.(no cloves)

Take a look at my website, you'll find loads of pictures and also differences between the 2 R65GS and an R80G/S. I have an unrestricted one from the danish army, and there is a dutch merchant who sells unrestricted french versions (now and near future he gets more). Here is a picture of mine taken yesterday
.
http://westerbaen.tweakdsl.nl/R65GS/200/IMGP2572e.jpg

www.forcemotorcycles.com Have some ex-Danish army R65GS's for sale on their web site. If you have a use for one they look like ideal examples.

First you have to find the source/cause of the problem.

Tyres 'cupped'?

Tyres out of ballance?

Steering head bearings loose?
Swing arm bearings loose?

Drive shaft bearings going?

Valves correctly adjusted - remeber end float

Carbs ballanced correctly and not leaking?

Then you can think about engine ballance being teh source.. assumeing the road is flat of course.

If I were you i would do some carb maintenance. Change the needles and needle jets for new ones, and install a pair of new diaphragms. Then adjust carbs. finall road test the bike at your preferred cruising speed. If it vibrates, adjust -ONE- of teh carbs throttle cable a little bit, say 1/6th of a turn. does not matter which way. then re test the bike. If the vibration is worse, adjust it the other way. If better repeat the adjustment until it is worse, then reverse that adjustment until it is as good as it gets. The throttles only open a butterfly valve. carburettor opening is done by the diaphragms so they need to be similar. if the cylinders produce different amounts of power, there will be vibration. This advice assumes you have a good pair of plugs and the tappets are adjusted the same on both sides. Sometimes (not often)a coil with favour one side