By slipped do you mean the "half clutch" maneuver? Or the old power shift sans clutch in the old 70s muscle cars. I read that a full clutch pull is sometimes worse than a 3/4. It seems a little bit of an art to find the happy shift. Especially 1st to 2nd. I've tried a little preload on the shift lever and not quite a full clutch pull. Bike appears to like that and at times shifts like butter. My thought is the smoother / quieter the shift the better. It also likes to shift 1st to 2nd when the choke is on. Which essentially tells me to keep a little more throttle.
Well -- here's my understanding which is tempered by my relative inexperience in the matter compared to some of the folks on this forum.
The K75 clutch, being a dry clutch, is to be treated just like the clutch of a car. In other words, it should be either all the way engaged or all the way disengaged, I.e. lever all the way out and hand completely off or lever all the way in. Just like the clutch pedal of a car -- you should never ride it with the foot, but always get your foot completely off when not engaged. This stands in contrast to a wet MC clutch which, being bathed on oil, doesn't care whether its being ridden or not.
For me, having burnt thru clutches to the tune of over $1200 early in my Kbike career, that means hand off the lever unless I'm shifting or idling at a stop, in which case the lever is fully in. I find that the k75 is so smooth in first gear that I rarely need to feather or slip the clutch (by that I mean hold the clutch lever halfway between in and out while giving throttle) to do any maneuvering. I can do tight u-turns at walking speed in 1st with my hand completely off the lever, which is something I would have needed to feather the clutch for on my old Honda 550/4.
Now, having said that, most of the time when shifting thru gears to get up to speed quickly, I speed-match the rpms and barely use the clutch at all to shift. But -- once I've reached target speed, my hand is off the lever completely. Basically, my understanding is that your K clutch needs to be adjusted with the proper amount of free play. If you ride with your hand on the lever with enough pressure to bring the lever within that free play region, you're burning up your clutch and helping it to a premature death.
So, my riding style is based on the above credo because that's what I learned from my old-school Beemer mechanic buddies back in the 2000s. If I misunderstood what they were telling me, somebody please tell me now!
This bike will nickel and dime me to death
I would caution you against spending any money unless you know what you're spending it on -- you can go broke real fast that way. For instance, I've never done anything to the fuel system except replace the pump because it failed completely. if you're missing or stuttering, there are a number of things that could be that have nothing to do with the tank. A most likely candidate for missing is the spark plug cables which fail after time. I replaced them all with OEMs T least once in 14 years ($280!) and recently replaced one of them again with the aftermarket silicon ones ($80 for set of three) from Beemer boneyard. If it is a spark plug cable, it will get worse, then you'll know to replace it. In the meantime, park the bike outside, take the spark plug cover off, wait till it gets dark, throw a blanket over the headlight, and look at the plugs to see if the spark is arcing off any of the cables. If it is, then the spark isn't getting to the plug so the cylinder isn't firing. It gets worse over time...at some point you're running on two cylinders and you know you have a problem and where to look for it.
It seems a little bit of an art to find the happy shift. Especially 1st to 2nd. I've tried a little preload on the shift lever and not quite a full clutch pull. Bike appears to like that and at times shifts like butter. My thought is the smoother / quieter the shift the better. It also likes to shift 1st to 2nd when the choke is on. Which essentially tells me to keep a little more throttle.
The choke isn't really a choke -- all it does is add some throttle to increase the idle RPMs so it doesn't stall out when idling cold. Not sure how that could affect shifting...Have you done the FD and DS splines yet? That should really help with the butteriness of the shifting.
I'm always reminded of Johnny's words of great wisdom... More motobrickng and less hand-wringing, or something to at effect. Johnny's philosophy is make sure your AAA is paid and ride it. When something is wrong with it, it will let you know and 99.9% of the time it will get you home safely first.
My humble $0.02...
Van