Clunk sound from top of engine

I've noticed this clunking sound i've been getting since upping the jets and the new air filter.

In a nutshell, going from third to second, blip the throttle as i downshift, and instead of the engine reving, i get a clunk, i'm putting it down to a piston but again cant be sure.

I should point out it doesn't happen all the time, but happen enough to cause the back wheel to lockup.

She's going in for a valve clearance this Friday coming, so i'm hoping that shows up something.

Any idea's ?

A clunk as in the engine misses a beat?

Sometimes when I blip on a downshift, the engine dosnt go with it, it just missfires. Maybe this is what you are getting?

Originally Posted by Alpinestarhero

A clunk as in the engine misses a beat?

Sometimes when I blip on a downshift, the engine dosnt go with it, it just missfires. Maybe this is what you are getting?

Couldnt really explain it better, it's as if the engine is missing a beat, altho i get the feeling it's only on one cylinder it happens, which bring me to my theory of the one of the pistons is getting a slap, maybe even stuck..