I have an issue with my 78 r80/7 where when I try to down shift I can’t engage the shifter I press down and nothing happens.. unless I click up a gear and then go down. Then it engages and I can shift down. The other thing I can do is kind of flutter the shifter if that makes sense. Kind of push it down with the edge of my foot and let it flap up a little. Then I can down shift. Anyone know what I mean?
http://www.rubberchickenracinggarage.co ... stment.pdf
Secondly, it might be time to lubricated the input splines to the transmission. This can sort of be done by sliding the transmission (and everything behind it) backwards about 3/4" and getting a stiff brush down to the splines. Probably best just to pull the transmission and do thorough cleaning.
'78 R100/7 '69 R69S '52 R25/2
So, if I am correct, your shifter link has an adjustable rod on it. I would check to see if your foot peg is where you want it and the shift lever is properly adjusted so when you do shift, your foot engages the lever the way it should.
As for the clutch, by all means check and adjust if needed. My 78RS has a grease fitting on the transmission clutch lever, give it a shot of grease. If you haven't greased the transmission input shaft, that is also a good thing to do.
The transmissions on this year bike are pretty robust. unless you have high miles or have been really hard on it, I don't think you should have to open the transmission up. A gear oil change and inspection of the magnetic plug for excessive metal bits may point to an internal problem. Cheers, St.