Unfortunately, it a forever. You see, the one [output] transmission shaft is constantly turning with the engine. The other [output] shaft is connect to the rear wheel via chain. The clunk is when a sliding gear enters a spinning gear as it enters 1st gear.
For the clutch workings, the big clutch outer runs with the engine, the clutch inner spins with the engine [when in N], but when you pull the clutch in, the inner is still spinning; but once you step on 1st, the clunk, then the clutch inner stops spinning.
Does not matter new, well broken in, or a high miler, it's the spinning, noisy mechanics of the bike and that gear separation method. You won't find any posts about 1st gear replacements; so there really is no worry about.
For the clunk; I start in 1st, then slowly take off and let the bike pull me at idle to warm up. No clunk. 20k or so miles, if the traffic light is short, I hold the lever in and am always in 1st if it calls for a stop. No clunk. If I think I'm making heat, clutch in, not transfer of plate to plate for heat dissipation, I still catch N as if new.
Take it for what it worth... propane torched a new steel clutch plate, discolored blue and all, put it on a surface plate and notice no warp. So I figured if that plate takes the kind of heat, then a steel plate will never see kind of heat with my long holds, doubt it will turn color with the oil feed it gets anyway.
Tormenting the motorcycling community one post at a time