Hello Felix, and welcome to NSR-WORLD.
Is your transmission "wet" or "dry"?
In case you're unaware, our Honda approved English Service Manual is available here »
Direct link to Section 9 - Transmission Troubleshooting
First thing I would suggest is to get the correct fluid in the transmission. Then check the service information regarding wear limits (both Clutch and Transmission sections), and get back to us. Bear in mind even the newest MC21 motor is over 30 years old now, and things do wear out, but believe it or not, it could be something as simple as a slightly misadjusted clutch cable.
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Andy.
NSR-WORLD.COM
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