needle adjustment on '07 40ex

[dave07ex]

I have a MY07 400ex. Did I read correctly on a previous thread that the needle position is not adjustable on the MY07? I'm just trying to get a plan in order for the exhaust install/tuning. Before anyone brings it up, yes, I did buy a D-shaped tool for the fuel screw.

[dave07ex]

Anyone???

[F-16Guy]

It doesn't have slots like the older models, but you can remove the needle from the slide, install a thin washer on it, and re-assemble, and it will raise the needle just like moving a clip does. The fuel screw (D shaped screw) controls the idle circuit, which is totally separate from what the needle controls. If it's hard to start cold and/or pops on decelleration, turn the screw CCW to richen the mixture. The adjustment range of the screw is only probably a little past three turns out. If you need to go past that, you'll need to change to the next larger pilot jet. Most people on this site usually go with a 40 or 42 pilot (38 stock) from the start. As for the main, depending on altitude and parts you install, you'd probably want around a 150-155 assuming the motor is stock internally.

[dave07ex]

Thanks for the input on the needle. I wasn't sure what it meant by "non-adjustable" but I haven't removed the carb yet either to see it for myself. From reading other posts on jetting, I've seen that needle adjustment is a regular thing with these type of mods. I'm assuming that shimming the needle in my case may also be necessary.
I'm going with HMF sport full system. The only other mods are k&n in a sealed aluminum box (no intetions of running w/o a lid). Motor-wise, everything else is stock, and will likely remain that way for a while. I was planning on starting with a 42 pilot and 160 main. The 160 main may be slightly rich, but I won't know until we test it out.

[F-16Guy]

Yeah, my guess is that it will be pretty rich. I have a 162 main and a 42 pilot, and I'm running an 11:1 416cc with a cam. It never hurts to be a little rich, so you can start there and work down. Jets are cheap, and it only takes a minute to swap out the main. I just turn the gas off and run the carb dry, and then remove the float bowl plug and remove the main with a 1/4" drive ratchet and 1/4" socket. As far as the needle goes, you probably won't have to touch it. Get the main dialed in first, and then see if there are any problems in the midrange. Mine has always run the best with the needle in the stock location (I've tried moving it around a couple of times).

[BEAVER.989]

In my limited experience, I have come to believe that it requires a bit more than exhaust and intake mods to require a neeedle adjustment. I don't think the needle needs to be messed with until after one gets into more significant mods.

After going through the process of shimming my needle, I quickly returned it to the stock position.

[dave07ex]

Thanks for the input guys. Like I said, I'm looking to set up a plan and starting points for the tuning settings.