Hi guys, today my GS went to the dyno for some testing and fine tuning.
The result so far is 34kw on the rear wheel, but there is a problem. The bike is running lean from 4000 to 7000 rpm.
Does somebody know how i can fix this?

Specs:
1990 GS
Dynojet stage
K&N open airfilter
Open exhaust (takkoni) on stock pipes



Greetz dB

A couple of small washers under the jet needle clips should address midrange leanness.

I see that you have the dynojet kit.  Many people have had issues with dynojet stuff on this bike.  If you can get it working to your satisfaction then great.  Also, the dynojet needle should have multiple clip positions on the needle, so you can just move the clip down one or two slots on the needle to address midrange leanness instead of needing washers.