Sometimes clunk and resistance shifting into 1st. and 2nd.

I just bought My 1986 K100rt my first BMW. The bike has about 50,000 miles on it and seems to run fine, although it's new to me so I'm cautious. Sometimes it clunks and has resistance shifting into 1st and 2nd. My first instint with the stiffly shifting gears. Is to adjust the clutch but don't want to jump in ignorant. I'm waiting for a hook wrench in the mail so that I can properly check the gear oil. (very cool by the way) Perhaps these bikes just shift this way, but it dosn't seem right for such a well made bike. I alao hear a raspy noise as I accellerate from first to second. Any thoughts?
Cape Cod Doug

Regardless of whether there is something wrong here, these bikes need a long, slow lever movement compared to modern sports bikes. You'll get used to it.

I'd check the oil. A lack of oil or even water in the oil can make shifting harsh. I use a welding rod. Dip it in using my finger as a stopper on top of the filler cap surface, then measure between 116mm and 126mm. I have found that I don't always recognise water in the oil by looking at the dipstick so changing is always good.

clutch adjustment is very important. it can make a huge difference.
afair the freeplay is 4mm on the lever and 75mm of cable lenght by the gearbox.

Thanks JoelB
It's good to know about the shifting and the long, slow lever movement, I'll keep that in mind. As for using a welding rod for a dip stick I assume you just let it bottom out, otherwise how would you get an accurate reading? I'm going to just change the oil along with most of the fluids because I want to know they are right and new. In another reply It was suggested to me that I use 75-140w synthetic in the gear box when the owners manual says to use 80 weight. What's your opinion on this?
Thanks Beachgem

Hey Zonenfeile
Thanks for your reply and advice. I will adjust the clutch. I am hesitant to use 75-140W since the manual recomends 80 or 90 weight, I assume you've done this. I'd like to hear from others who have. Also with reguard to using synthetic after having always used petrol oils I've heard that this might not be good for the 24 year old seals. I'm new to bikes this old and want to error on the side of caution but my intuition tells me your advice is good.