Been a while since I pimped my KLX, so I thought I would give it another shot.
I know what you are saying. Seen that picture. But it is what is under the hood that is important.
That is a Wossner, forged aluminum piston 102mm, giving 680cc more or less of fire breathing power.
Comparison with the stock piston:
Obvious shortened coated skirt. Also 76 gr lighter. Other than the difference in size, the top shares the same design as the stocker, so compression ratio should be the same.
The piston was purchased from LA sleeve, comlete with rings, pin and circlips for $185. They or the machinist of your choice can bore and hone for around $80 more.
Only 200 miles on it, so not prepared to announce the mother of all mods yet, but so far money well spent.
First thing I noticed is that there is a lot more tension in the #1 & 2 rings. I have used no oil. At steady state throttle, little vibration, get on the gas and you know it is a single however. Yes the exhaust is louder, in a lower menacing way. What you really notice is the increased torque between 3 and 6500rpm, especially in 3rd, 4th and 5th gear. Making passes, you would swear you were riding a larger displacement twin. With some larger intake valves this would be a real firebreather.
I will be off to DV, next week to further break it in and when I return I will do some runs on my local hill to compare roll on speeds against my prior runs on stock and prebore modified runs. I have already beaten the stock run on my 2/10 mile hill in the first 100 yds before I shut it down.