Decided to go with this carb after kicking the daylights out the bike after spilling it. Thought to myself this is useless if I am going to do harescrambles and made me second guess if the xr would be better than a crfx(push button). Well, since the Edlebrock pumper has gone bye bye and the other pumpers just seemed expensive and daunting to set up and tune I decided to go with the Mikuni from XRsonly. Have to say the installation was smooth, love the one throttle cable simplicity and function which came with the carb. Now, when they say it is tuned that is a yes and a no. The carb is set for "average", meaning 3200' elevation. Didn't know this until I tried to run the bike and found it was running too rich. Stumbled at low rpms, flat build up and black spark plug. Looked at the paper they sent and made me thing, wait a minute, I am at 500' so that should make me lean. Called XRsonly a couple of times and found them to be very helpful. Basically the carb was intended for bigger bore applications and the bike requires the smaller jets. Which on the paper puts me at 5000' elevation(according to the paper). So I went with the smaller jets. The needle was on the second clip from the top so I didn't want to risk going all out lean and risk the bad things that can happen when too lean. So small jets was to be tried first. I was able to check the needle and change the jets without taking the carb off! Took the bike for a ride and it was great. Revs much more. Better response. Starts one kick from TDC. Now, the real treat. Flooding. Did a harescramble today and spilled it good. Top of the bike was slanted down hill. Took a few seconds get myself together and left it up. Got on the bike and thought, ok, here is the moment of truth. 1 KICK! Other times I bogged out such as on a hill(amateur, ), find TDC and away I went. Now, I can imagine what this is going to perform like with the 277mm piston I have waiting to install.