Clunk is normal, pop is normal, okay bye. Just kidding. Here are the clues:
The Pop and the science applied:
Fuel injection mimics a carburetor, meaning, even though the throttle is shut off, the fuel is still being pulled out of the jets but not so much. FI goes lean the same way so upon lift, you apply the abstract of for every action, what just happened? You sucked in fresh OXYGEN into the muffler and refired what little fuel was unspent. Thus the refire of the fuel and POP goes the science of it. It's so in the absolute, ask the buyer to explain it another way the bike has a problem? One down.
The Clunk and the mechanics applied:
There are two shafts in the transmission. One is hooked to the wheel, the other is hooked to the engine. One shaft is locked to the spinning crank and never stops. A friction plate is locked in with the spinning crank. A steel plate is locked with the wheel. Oil cools and lubes any friction induced and clings onto the parts. A free spinning gear on each shaft remains stationary. A sliding gear is locked on each shaft. When the clutch lever is pulled in, the shift lever pressed down, the free spinning gear is going to receive the connection of the sliding gear entry to lock into 1st gear. The combination of a liquid in between a moving part and a stationary part is going to mechanically connect, better known as; A Clunk into 1st gear.
The abstract explaining the look inside:
As if you dipped a paper plate in honey, dipped both hands in it too, placed the dripping paper plate flat between your hands, boom, you're a clutch pack.
a. As if both engine and wheel are locked together, now pull one hand away and begin to spin it on the plate, while the other hand remains stationary.
b. As if the plate is stuck to both hands and now the plate is at this angle / and touches both the spinning (friction) plate next to it and the other touch point at the stationary (steel) plate.
c. As if continuing to circulate your one hand so as to break the honey free off of the plate from your one hand. Thus, stopping the free spinning, or free wheeling gear from the honey lock = No Clunk.
Conclusion:
Go back to stock so no pop is noticed. Go to 1st gear before you start the bike up to eliminate the clunk tell him. You'd be a fool not to buy the bike better known as Bulletproof. NPF [no problem found]
Signed,
NOLTT
Tormenting the motorcycling community one post at a time